Merge branch 'master' into fix/issue-790-slice-a-heartbeat-policy

Review #526 found that event_type reached the serialized timeline payload
without crossing the redaction/validation boundary every other free-text
field on the same event crosses. A synthetic secret-shaped 40-hex canary
was redacted through message but survived verbatim through event_type on
the same control-plane record.

CTH heading path: CTH_TYPES is now the single authority for what a CTH
type may be. canonical_thread_handoff.is_known_cth_type() is that
authority, used by format_cth_body (write), assess_cth_comment (assess),
and now the read path too; parse_cth_comment reports membership as
cth_type_known and stays total. adapt_cth_comments serializes
handoff:<type> only for a declared type and otherwise emits the constant
handoff:unrecognized, so arbitrary, malformed, secret-shaped, or
whitespace-manipulated heading content never becomes an event_type.

Control-plane path: a stored event_type is treated as source data.
_safe_cp_event_type accepts only an ordinary identifier that is not a
bare secret-shaped hex run and that a redaction pass leaves unchanged;
anything else fails closed to the constant unsafe:redacted and marks the
event sensitive. The value is never emitted verbatim, never partially
sanitized, and never rewritten into a different valid-looking type.

Remaining serialized-field audit: event_key ids must be plain numeric
identifiers, the CTH adapter refuses a scope it cannot express, per-source
failure reasons are redacted (they can quote an authenticated fetch error),
and echoed scope/filter values are guarded so reflection is not a bypass.

Legitimate values are preserved: every declared CTH type, the real
producer types (assigned, lease_released, lease_adopted,
dependency_edge_state_change, allocation, pr.opened, lease.renew), and
the existing issue, PR, evidence, and full-SHA references.

Tests seed the canary independently through both event_type paths with a
benign message, so message redaction cannot be why they pass; each
inspects event_type directly, asserts the canary is absent from the
complete serialized payload, and asserts scan_for_secrets finds nothing.

tests/test_webui_timeline.py 64 passed, 15 subtests
pytest -k webui 362 passed, 285 subtests
pytest -k redact 79 passed
tests/test_canonical_thread_handoff.py tests/test_control_plane_db.py 29 passed

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

branch_cleanup_guard.py

@@ -163,7 +163,19 @@ _TERMINAL_OWNERSHIP_STATUSES = frozenset(
     {"released", "abandoned", "done", "blocked", "terminal", "closed"}
 )
 _EXPIRED_STATUSES = frozenset({"expired"})
-_STALE_STATUSES = frozenset({"stale", "stale_dead_process", "stale_missing_worktree"})
+_STALE_STATUSES = frozenset(
+    {
+        "stale",
+        "stale_dead_process",
+        "stale_missing_worktree",
+        # #790 Slice A heartbeat-lifecycle bands. Listed here so they are
+        # *classified* rather than falling through to the unknown-status branch;
+        # they still block unless the ownership record proves
+        # ``reclaim_allowed is True``, so the O2 fail-closed rule is unchanged.
+        "stale_missed_heartbeat",
+        "stale_absolute_cap",
+    }
+)
 
 
 def _norm_str(value: Any) -> str:

canonical_thread_handoff.py

@@ -46,6 +46,17 @@ _FIELD_RE = re.compile(
 )
 
 
+def is_known_cth_type(value: str | None) -> bool:
+    """True when *value* is a declared member of the :data:`CTH_TYPES` contract.
+
+    ``CTH_TYPES`` is the single authority for what a CTH type may be. The
+    heading a comment carries is free text, so a *read* path that turns a parsed
+    type into something durable — a serialized field, a routing decision — must
+    check membership here rather than trust the parse or keep a list of its own.
+    """
+    return (value or "").strip() in CTH_TYPES
+
+
 def format_cth_body(
     *,
     cth_type: str,
@@ -60,7 +71,7 @@ def format_cth_body(
 ) -> str:
     """Render a canonical CTH comment body."""
     normalized_type = (cth_type or "").strip()
-    if normalized_type not in CTH_TYPES:
+    if not is_known_cth_type(normalized_type):
         raise ValueError(
             f"unknown CTH type '{cth_type}'; expected one of {sorted(CTH_TYPES)}"
         )
@@ -101,6 +112,12 @@ def parse_cth_comment(body: str) -> dict[str, Any] | None:
         fields[key] = match.group(2).strip()
     return {
         "cth_type": cth_type,
+        # The heading capture is unconstrained free text, so the parse states
+        # whether it satisfies the CTH_TYPES contract instead of leaving every
+        # reader to decide (or forget). Parsing stays total — an unknown type is
+        # still parsed and reported, never raised on — but a reader that turns
+        # the type into a durable value can now tell the two apart.
+        "cth_type_known": is_known_cth_type(cth_type),
         "fields": fields,
         "raw_body": text,
     }
@@ -119,7 +136,7 @@ def assess_cth_comment(body: str) -> dict[str, Any]:
         }
 
     cth_type = parsed.get("cth_type") or ""
-    if cth_type not in CTH_TYPES:
+    if not is_known_cth_type(cth_type):
         reasons.append(
             f"unknown CTH type '{cth_type}'; expected one of {sorted(CTH_TYPES)}"
         )

docs/mcp-tool-inventory.md

@@ -100,6 +100,7 @@ that gates each call, not which tools exist.
 - `gitea_get_profile`
 - `gitea_get_runtime_context`
 - `gitea_get_shell_health`
+- `gitea_heartbeat_issue_lock`
 - `gitea_heartbeat_reviewer_pr_lease`
 - `gitea_inspect_workflow_lease`
 - `gitea_issue_irrecoverable_provenance_authorization`

docs/webui-local-dev.md

@@ -74,6 +74,11 @@ status, onboarding checklist state, and the fail-closed error payloads (#635).
 | `/api/actions/{id}/preview` | Mutation ledger preview (GET, read-only) |
 | `/leases` | Lease and collision visibility (#433) |
 | `/api/leases` | JSON lease/collision export |
+| `/sessions` | Phase 1 shell stub — session inventory (backed by #636) |
+| `/inventory` | Phase 1 shell stub — unified inventory (backed by #636) |
+| `/timeline` | Phase 1 shell stub — workflow event timeline |
+| `/policy` | Phase 1 shell stub — capability/role policy placeholder |
+| `/insights` | Phase 1 shell stub — operational insights placeholder |
 
 Most routes are GET-only. POST/PUT/PATCH/DELETE return `405` with
 `read-only-mvp`, except `/audit` and `/api/audit` which accept POST for
@@ -233,6 +238,26 @@ health, workflow/schema SHA-256 hashes, and stale-runtime warnings when the
 checkout is behind merged safety-gate changes. Restart guidance links to #420;
 no tokens or MCP restart actions are exposed.
 
+## Application shell — Phase 1 (#638)
+
+The console shell (`webui/layout.py`) renders a grouped navigation driven by a
+single nav-config module, `webui/nav.py`. Nav groups follow the epic #631
+Phase 1 information architecture: **Health, Traffic, Runtime/Sessions,
+Projects, Inventory, Timeline, Policy** (placeholder), and **Insights**
+(placeholder). Live views and Phase 1 placeholders (`stub`) are declared in one
+place so the layout and the route table cannot drift.
+
+The header carries two read-only status badges — an **environment** badge
+(`local` for loopback binds, `remote` otherwise, derived from `WEBUI_HOST`) and
+a **mode: read-only** badge — plus a **Docs** link to this document. No
+privileged action controls are present in the Phase 1 shell.
+
+Not-yet-implemented surfaces (`/sessions`, `/inventory`, `/timeline`,
+`/policy`, `/insights`) resolve to graceful read-only stub pages instead of
+404s; their backing views land in later child issues of #631 (the inventory
+surfaces are backed by #636). Mutating methods on stub routes still fail closed
+with `read-only-mvp`.
+
 ## Deployment boundary (#435)
 
 MVP serves on loopback by default. Binding `0.0.0.0` or `::` is **refused**
@@ -292,6 +317,108 @@ health, workflow/schema SHA-256 hashes, and stale-runtime warnings when the
 checkout is behind merged safety-gate changes. Restart guidance links to #420;
 no tokens or MCP restart actions are exposed.
 
+## Workflow-event timeline (#637)
+
+`GET /api/v1/timeline` is a read-only, versioned aggregation of workflow
+events from every available source into one normalised, filterable stream. It
+is the model layer for the Phase 1 timeline console view (a later child issue
+of #631); this issue ships the schema, adapters, and read API only.
+
+### Schema (versioned)
+
+`webui/timeline.py` declares `TIMELINE_SCHEMA_VERSION` (currently `1`) and the
+frozen `WorkflowEvent` record. Every response carries `schema_version` so a
+consumer can branch on shape. One event:
+
+```json
+{
+  "source": "control_plane",
+  "event_type": "lease.renew",
+  "event_key": "cp:1421",
+  "timestamp": "2026-07-23T02:00:00Z",
+  "actor": null,
+  "role": null,
+  "issue_number": 637,
+  "pr_number": null,
+  "session_id": null,
+  "tool_name": null,
+  "decision": null,
+  "message": "lease renewed",
+  "correlation_id": "issue#637",
+  "evidence_refs": [],
+  "sensitive": true
+}
+```
+
+`event_key` is stable and unique per source (`cp:<event_id>`,
+`cth:<kind>:<number>:<comment_id>`), so pagination and dedup are deterministic.
+
+### Sources and field authority
+
+| Source | Adapter | Authority |
+|---|---|---|
+| Control-plane `events` ⋈ `work_items` | `adapt_cp_events` | `event_type`, `message`, `timestamp`, issue/PR scope come from the CP database, read through a `mode=ro` URI (never creates the DB or runs migrations) |
+| Gitea Canonical Thread Handoff comments | `adapt_cth_comments` | `actor`, `role` (next owner), `decision`, `evidence_refs`, `timestamp` come from the parsed CTH comment body (`canonical_thread_handoff`) |
+
+Handoff comments are thread-scoped: they are only read when the request filters
+by a single `issue` or `pr`. Otherwise the handoff source reports `not run`
+with a reason — it is never rendered as empty-and-healthy. Each source degrades
+independently: an unavailable control-plane DB or a failed comment fetch is a
+`sources[]` entry with `ok:false` and a `reason`, never a dropped timeline.
+
+### Query parameters
+
+`issue`, `pr`, `session` (conjunctive filters); `limit` (default 50, max 500)
+and `offset` for pagination; `remote`, `org`, `repo` to override the default
+registry-project scope. Events sort ascending by
+`(timestamp, source_rank, event_key)`; missing timestamps sort last.
+
+### Filter authority, and refusing what cannot be answered
+
+A filter dimension is only meaningful for a source whose records carry it.
+Each source declares its own support in `_SOURCE_FILTER_SUPPORT` and reports it
+per response as `supported_filters` / `unsupported_filters`:
+
+| Source | issue | pr | session |
+|---|---|---|---|
+| `control_plane` | yes | yes | **no** — the `events` table is `(event_id, work_item_id, event_type, message, created_at)` and records no session |
+| `gitea_handoff` | yes | yes | yes — a CTH comment declares its own `Session:` field |
+
+`session_id` is read only from that declared CTH field. It is never inferred
+from a work item, an actor, or message text, and a value that is
+redaction-altering or bare-secret-shaped is dropped rather than emitted.
+
+When **no source that ran** can carry a requested dimension, the request is
+refused rather than answered: the response is `422` with `ok:false` and a
+structured `error` naming `unsupported_filters` and the per-source reason. A
+`200` with zero events would tell an operator that no such activity exists,
+which is a stronger — and false — claim than "this cannot be answered here".
+A source that *can* answer the dimension and simply matched nothing still
+returns `200` with `ok:true` and an empty page.
+
+### Redaction
+
+Every free-text field (event messages, decision/proof text, roles, actors) is
+passed through the console redaction policy (`webui.console_redaction`, backed
+by `gitea_audit.redact`) before it leaves the module, failing closed to the
+placeholder. No unredacted tool arguments or secrets are ever emitted, and a
+generation error never drops raw data to a caller or a log.
+
+Redaction also runs *before* any structured value is derived from free text.
+`evidence_refs` are extracted from already-redacted proof/decision text, and a
+commit reference is recognised only where the text declares one (`commit`,
+`head`, `base`, `sha`, …). An undeclared 40-character hex run has the exact
+shape of a Gitea access token, so it is never lifted out of prose into a
+structured field. Every reference is then independently revalidated against an
+allowed shape and a second redaction pass immediately before serialization;
+anything unproven is dropped and the event is flagged `sensitive`.
+
+### Tests
+
+```bash
+pytest tests/test_webui_timeline.py -q
+```
+
 ## Tests
 
 ```bash

gitea_mcp_server.py

@@ -2020,6 +2020,7 @@ import allocator_dependencies  # noqa: E402
 import dependency_graph  # noqa: E402  # #784 durable dependency edges
 import control_plane_db  # noqa: E402
 import lease_lifecycle  # noqa: E402
+import lease_policy  # noqa: E402
 import workflow_dashboard  # noqa: E402  # #605 live queue/lease dashboard
 import incident_bridge  # noqa: E402
 import sentry_observability  # noqa: E402  (#606 optional Sentry observability)
@@ -2262,7 +2263,6 @@ import canonical_comment_validator as ccv  # noqa: E402
 # GITEA_ISSUE_LOCK_DIR, bound to the current MCP session via a per-PID pointer.
 # Legacy global path retained only for test/doc references — do not seed manually.
 ISSUE_LOCK_FILE = "/tmp/gitea_issue_lock.json"
-WORK_LEASE_TTL_HOURS = 4
 AUTHOR_ISSUE_WORK_LEASE = "author_issue_work"
 VALID_WORK_LEASE_OPERATIONS = frozenset({
     AUTHOR_ISSUE_WORK_LEASE,
@@ -2562,7 +2562,12 @@ def _build_author_issue_work_lease(
     host: str | None,
 ) -> dict:
     created = _work_lease_now()
-    expires = created + timedelta(hours=WORK_LEASE_TTL_HOURS)
+    # #790 Slice A: the window comes from the central policy, not a literal here.
+    # It is also now a *sliding* window — the lease lives ``initial_ttl_minutes``
+    # past its last valid heartbeat rather than a fixed four hours past its
+    # creation, so an abandoned task stops holding the claim within one TTL.
+    policy = lease_policy.policy_for(lease_policy.TASK_CLASS_AUTHOR_ISSUE_WORK)
+    expires = created + timedelta(minutes=policy.initial_ttl_minutes)
     return {
         "operation_type": AUTHOR_ISSUE_WORK_LEASE,
         "issue_number": issue_number,
@@ -2573,6 +2578,15 @@ def _build_author_issue_work_lease(
         "created_at": _work_lease_timestamp(created),
         "expires_at": _work_lease_timestamp(expires),
         "last_heartbeat_at": _work_lease_timestamp(created),
+        # #790 AC-N1: the ownership key for this task. Distinct from the recorded
+        # PID, which is the shared daemon and identifies no individual task.
+        "task_session_id": issue_lock_store.mint_task_session_id(
+            AUTHOR_ISSUE_WORK_LEASE
+        ),
+        # #790 AC-N8: the explicit lifecycle marker. Its absence — never a
+        # timestamp comparison — is what makes a lock legacy.
+        "lifecycle_version": lease_policy.LIFECYCLE_HEARTBEAT_V1,
+        "heartbeat_count": 1,
     }
 
 
@@ -4342,6 +4356,138 @@ def gitea_lock_issue(
     return result
 
 
+@mcp.tool()
+def gitea_heartbeat_issue_lock(
+    issue_number: int,
+    branch_name: str,
+    task_session_id: str | None = None,
+    remote: str = "dadeschools",
+    host: str | None = None,
+    org: str | None = None,
+    repo: str | None = None,
+    worktree_path: str | None = None,
+    expected_generation: int | None = None,
+) -> dict:
+    """Prove an owned author issue lease is still active (#790 Slice A).
+
+    The task-liveness signal the lifecycle was missing. Before this, an author
+    lease carried a fixed four-hour expiry that nothing could shorten, and the
+    only liveness evidence was the recorded PID — the long-lived MCP daemon,
+    which stays alive across every task it serves and so proved nothing about
+    whether the authoring task still held the work.
+
+    Each successful call slides the lease ``initial_ttl_minutes`` past *now*
+    from the central policy, so an actively heartbeating session is never
+    evicted while an abandoned one releases its claim within one TTL.
+
+    What this tool cannot do, by construction:
+
+    * **Acquire.** It refuses when no durable lock exists.
+    * **Take over.** Exact issue, branch, realpath-normalized worktree,
+      claimant username, claimant profile, and recorded task-session identifier
+      must all match; a superseded session holding an older identifier is
+      refused.
+    * **Revive.** A lease already past its grace is not heartbeatable — that
+      would let a session restore ownership it had stopped proving. It must use
+      the sanctioned reclaim path, which mints a new generation.
+
+    A lock predating the heartbeat lifecycle is rebound rather than heartbeated:
+    its exact owner is re-verified and a genuine task-session identifier and
+    first heartbeat are minted (#790 AC-N8). The rebind is decided server-side
+    from the durable lifecycle marker; there is no caller-facing switch.
+
+    Args:
+        issue_number: The locked issue number.
+        branch_name: The branch recorded on the lock.
+        task_session_id: The identifier this session received when it acquired
+            or rebound the lock. It is a fencing token, not an ownership
+            assertion: it is compared against durable state and can only ever
+            cause a refusal, never grant anything. Omitted only when rebinding a
+            legacy lock, which has no identifier yet and mints one.
+        remote: Known instance — 'dadeschools' or 'prgs'.
+        host: Override the Gitea host.
+        org: Override the owner/organization.
+        repo: Override the repository name.
+        worktree_path: Author worktree recorded on the lock.
+        expected_generation: Optional fencing value. The per-issue flock already
+            serializes the read and the write, so this is for a caller that
+            wants to pin the generation it last observed across calls; a moved
+            generation fails closed.
+
+    Returns:
+        dict with 'success', 'performed', the sliding 'expires_at',
+        'last_heartbeat_at', 'lock_generation', 'task_session_id', the applied
+        'policy', and post-write 'freshness'; on refusal 'success'/'performed'
+        False with 'reasons' naming exactly what did not match.
+    """
+    blocked = _profile_permission_block(
+        task_capability_map.required_permission("heartbeat_issue_lock"),
+        issue_number=issue_number,
+        remote=remote,
+        host=host,
+        org=org,
+        repo=repo,
+        org_explicit=org is not None,
+        repo_explicit=repo is not None,
+    )
+    if blocked:
+        return blocked
+
+    resolved_worktree = issue_lock_worktree.resolve_author_worktree_path(
+        worktree_path, _canonical_local_git_root()
+    )
+    h, o, r = _resolve(remote, host, org, repo)
+    claimant = _work_lease_claimant(h)
+    identity = claimant.get("username")
+    profile = claimant.get("profile")
+
+    existing = _load_existing_issue_lock(
+        remote=remote, org=o, repo=r, issue_number=issue_number
+    )
+    if not existing:
+        return {
+            "success": False,
+            "performed": False,
+            "issue_number": issue_number,
+            "reasons": [
+                f"no durable lock for issue #{issue_number}; heartbeat cannot "
+                "acquire a claim (fail closed)"
+            ],
+        }
+
+    if issue_lock_store.is_legacy_lease(existing):
+        # AC-N8 exit route one: canonical exact-owner rebinding. The other exit
+        # is terminal retirement, which is Slice B.
+        outcome = issue_lock_store.rebind_legacy_lock(
+            remote=remote,
+            org=o,
+            repo=r,
+            issue_number=issue_number,
+            branch_name=branch_name,
+            worktree_path=resolved_worktree,
+            identity=identity,
+            profile=profile,
+            expected_generation=expected_generation,
+        )
+        outcome["operation"] = "legacy_rebind"
+        return outcome
+
+    outcome = issue_lock_store.heartbeat_session_lock(
+        remote=remote,
+        org=o,
+        repo=r,
+        issue_number=issue_number,
+        branch_name=branch_name,
+        worktree_path=resolved_worktree,
+        identity=identity,
+        profile=profile,
+        task_session_id=str(task_session_id or ""),
+        expected_generation=expected_generation,
+    )
+    outcome["operation"] = "heartbeat"
+    return outcome
+
+
 @mcp.tool()
 def gitea_assess_work_issue_duplicate(
     issue_number: int,

issue_lock_store.py

@@ -15,15 +15,27 @@ import json
 import os
 import re
 import tempfile
+import uuid
 from contextlib import contextmanager
 from datetime import datetime, timedelta, timezone
 from typing import Any
 
+import lease_policy
+
 LOCK_DIR_ENV = "GITEA_ISSUE_LOCK_DIR"
 DEFAULT_LOCK_DIR = os.path.expanduser("~/.cache/gitea-tools/issue-locks")
-WORK_LEASE_TTL_HOURS = 4
 AUTHOR_ISSUE_WORK_LEASE = "author_issue_work"
 
+# Freshness classifications. ``STATUS_STALE`` remains the dead-PID band that
+# #753 recovery keys on; the two bands below are new in #790 Slice A and apply
+# only to leases minted under the heartbeat lifecycle.
+STATUS_LIVE = "live"
+STATUS_EXPIRED = "expired"
+STATUS_ABSENT = "absent"
+STATUS_STALE = "stale"
+STATUS_STALE_MISSED_HEARTBEAT = "stale_missed_heartbeat"
+STATUS_STALE_ABSOLUTE_CAP = "stale_absolute_cap"
+
 _SAFE_SEGMENT_RE = re.compile(r"[^A-Za-z0-9._+-]+")
 
 
@@ -253,6 +265,331 @@ def bind_session_lock(
     return path
 
 
+def _ownership_refusals(
+    lock: dict[str, Any],
+    *,
+    issue_number: int,
+    branch_name: str,
+    worktree_path: str,
+    identity: str | None,
+    profile: str | None,
+) -> list[str]:
+    """Exact-ownership mismatches between a durable lock and a live caller.
+
+    Shared by the heartbeat writer and the legacy rebind path so the two cannot
+    disagree about what "the same owner" means. Every field is compared against
+    durable state; nothing is taken on the caller's word beyond the identity the
+    server itself resolved.
+    """
+    reasons: list[str] = []
+    if lock.get("issue_number") != issue_number:
+        reasons.append(
+            f"lock targets issue #{lock.get('issue_number')}, not #{issue_number}"
+        )
+    if str(lock.get("branch_name") or "") != str(branch_name or ""):
+        reasons.append(
+            f"lock branch '{lock.get('branch_name')}' does not match '{branch_name}'"
+        )
+    if not _same_realpath(str(lock.get("worktree_path") or ""), worktree_path):
+        reasons.append(
+            f"lock worktree '{lock.get('worktree_path')}' does not match "
+            f"'{worktree_path}'"
+        )
+    lease = lock.get("work_lease") if isinstance(lock, dict) else None
+    claimant = lease.get("claimant") if isinstance(lease, dict) else None
+    claimant = claimant if isinstance(claimant, dict) else {}
+    recorded_identity = str(claimant.get("username") or "").strip()
+    recorded_profile = str(claimant.get("profile") or "").strip()
+    if not recorded_identity or not recorded_profile:
+        reasons.append("lock does not record both a claimant username and profile")
+    if recorded_identity and recorded_identity != str(identity or "").strip():
+        reasons.append(
+            f"lock claimant '{recorded_identity}' does not match active identity "
+            f"'{str(identity or '').strip() or 'unknown'}'"
+        )
+    if recorded_profile and recorded_profile != str(profile or "").strip():
+        reasons.append(
+            f"lock profile '{recorded_profile}' does not match active profile "
+            f"'{str(profile or '').strip() or 'unknown'}'"
+        )
+    return reasons
+
+
+def _refusal(reasons: list[str], **extra: Any) -> dict[str, Any]:
+    return {"success": False, "performed": False, "reasons": reasons, **extra}
+
+
+def heartbeat_session_lock(
+    *,
+    remote: str,
+    org: str,
+    repo: str,
+    issue_number: int,
+    branch_name: str,
+    worktree_path: str,
+    identity: str | None,
+    profile: str | None,
+    task_session_id: str,
+    expected_generation: int | None = None,
+    lock_dir: str | None = None,
+    now: datetime | None = None,
+) -> dict[str, Any]:
+    """Slide a heartbeat-lifecycle lease forward (#790 Slice A, A4).
+
+    The write happens inside the same per-issue ``flock`` that serializes
+    acquisition, and under the #772 generation compare-and-swap, so a heartbeat
+    can never race a concurrent reclaim: whichever lands first moves the
+    generation and the other fails closed.
+
+    Refuses — never revives — in every ambiguous case. A lease that has already
+    lapsed past its grace is *not* heartbeatable: allowing that would let a
+    session that stopped proving liveness restore ownership retroactively, which
+    is precisely the revival AC-N5 forbids. Such a session must go through the
+    sanctioned reclaim path, which mints a fresh generation.
+    """
+    current = _lease_now(now)
+    root = _ensure_lock_dir(lock_dir)
+    path = lock_file_path(
+        remote=remote, org=org, repo=repo, issue_number=issue_number, lock_dir=root
+    )
+    declared_session = str(task_session_id or "").strip()
+    if not declared_session:
+        return _refusal(["no task_session_id supplied (fail closed)"])
+
+    sentinel = flock_path(path)
+    try:
+        with _exclusive_file_lock(sentinel):
+            lock = read_lock_file(path)
+            if not lock:
+                return _refusal([f"no durable lock for issue #{issue_number}"])
+
+            if is_legacy_lease(lock):
+                return _refusal(
+                    [
+                        "lock predates the heartbeat lifecycle; it must be rebound "
+                        "by its exact owner before it can be heartbeated"
+                    ],
+                    lifecycle=lease_lifecycle_version(lock),
+                    legacy_lease=True,
+                )
+
+            reasons = _ownership_refusals(
+                lock,
+                issue_number=issue_number,
+                branch_name=branch_name,
+                worktree_path=worktree_path,
+                identity=identity,
+                profile=profile,
+            )
+            recorded_session = lease_task_session_id(lock)
+            if not recorded_session:
+                reasons.append(
+                    "lock declares the heartbeat lifecycle but records no "
+                    "task_session_id (fail closed)"
+                )
+            elif recorded_session != declared_session:
+                # A superseded session holding an old identifier cannot heartbeat
+                # over the session that replaced it.
+                reasons.append(
+                    "task_session_id does not match the session recorded on the lock"
+                )
+            if reasons:
+                return _refusal(reasons)
+
+            current_generation = lock_generation(lock)
+            if (
+                expected_generation is not None
+                and current_generation != expected_generation
+            ):
+                return _refusal(
+                    [
+                        f"lock generation changed: expected {expected_generation}, "
+                        f"found {current_generation}; another session reclaimed or "
+                        "replaced this claim (fail closed)"
+                    ],
+                    lock_generation=current_generation,
+                )
+
+            freshness = assess_lock_freshness(lock, now=current)
+            if not freshness.get("live"):
+                return _refusal(
+                    [
+                        f"lease is not live ({freshness.get('status')}): "
+                        f"{freshness.get('reason')}; a lapsed lease must be "
+                        "reclaimed, not heartbeated"
+                    ],
+                    freshness=freshness,
+                )
+
+            policy = lease_policy.policy_for(lease_task_class(lock))
+            expires = current + timedelta(minutes=policy.initial_ttl_minutes)
+            record = dict(lock)
+            lease = dict(record.get("work_lease") or {})
+            prior_heartbeat = lease.get("last_heartbeat_at")
+            lease["last_heartbeat_at"] = _format_lease_timestamp(current)
+            lease["expires_at"] = _format_lease_timestamp(expires)
+            try:
+                lease["heartbeat_count"] = int(lease.get("heartbeat_count") or 0) + 1
+            except (TypeError, ValueError):
+                lease["heartbeat_count"] = 1
+            record["work_lease"] = lease
+            record["lock_generation"] = current_generation + 1
+            save_lock_file(path, record)
+    except LockContentionError as exc:
+        return _refusal([f"issue #{issue_number} lock contention: {exc} (fail closed)"])
+
+    return {
+        "success": True,
+        "performed": True,
+        "issue_number": issue_number,
+        "branch_name": branch_name,
+        "worktree_path": worktree_path,
+        "task_session_id": declared_session,
+        "lock_generation": record["lock_generation"],
+        "prior_generation": current_generation,
+        "prior_heartbeat_at": prior_heartbeat,
+        "last_heartbeat_at": lease["last_heartbeat_at"],
+        "expires_at": lease["expires_at"],
+        "heartbeat_count": lease["heartbeat_count"],
+        "lock_file_path": path,
+        "policy": lease_policy.describe(lease_task_class(record)),
+        "freshness": assess_lock_freshness(record, now=current),
+    }
+
+
+def rebind_legacy_lock(
+    *,
+    remote: str,
+    org: str,
+    repo: str,
+    issue_number: int,
+    branch_name: str,
+    worktree_path: str,
+    identity: str | None,
+    profile: str | None,
+    expected_generation: int | None = None,
+    lock_dir: str | None = None,
+    now: datetime | None = None,
+) -> dict[str, Any]:
+    """Move a legacy lock into the heartbeat lifecycle (#790 AC-N8).
+
+    One of the two sanctioned exits from the preserved-expiry legacy state; the
+    other is terminal retirement, which is Slice B. Only the exact recorded
+    owner may rebind, and only while the legacy lock is still live under its
+    original absolute expiry — an already-expired legacy lease belongs to the
+    #760 renewal path or #601 reclaim, and this must not become a second, weaker
+    way to revive one.
+
+    The rebind mints a genuine task-session identifier and a genuine first
+    heartbeat. It does not fabricate history: the original creation and expiry
+    are preserved under ``legacy_origin`` for audit, and the new lifecycle's
+    absolute cap runs from the rebind, not from the legacy claim.
+    """
+    current = _lease_now(now)
+    root = _ensure_lock_dir(lock_dir)
+    path = lock_file_path(
+        remote=remote, org=org, repo=repo, issue_number=issue_number, lock_dir=root
+    )
+    sentinel = flock_path(path)
+    try:
+        with _exclusive_file_lock(sentinel):
+            lock = read_lock_file(path)
+            if not lock:
+                return _refusal([f"no durable lock for issue #{issue_number}"])
+            if not is_legacy_lease(lock):
+                return _refusal(
+                    [
+                        "lock is already on the heartbeat lifecycle; use the "
+                        "heartbeat path"
+                    ],
+                    lifecycle=lease_lifecycle_version(lock),
+                    legacy_lease=False,
+                )
+
+            reasons = _ownership_refusals(
+                lock,
+                issue_number=issue_number,
+                branch_name=branch_name,
+                worktree_path=worktree_path,
+                identity=identity,
+                profile=profile,
+            )
+            if reasons:
+                return _refusal(reasons)
+
+            current_generation = lock_generation(lock)
+            if (
+                expected_generation is not None
+                and current_generation != expected_generation
+            ):
+                return _refusal(
+                    [
+                        f"lock generation changed: expected {expected_generation}, "
+                        f"found {current_generation} (fail closed)"
+                    ],
+                    lock_generation=current_generation,
+                )
+
+            freshness = assess_lock_freshness(lock, now=current)
+            if not freshness.get("live"):
+                return _refusal(
+                    [
+                        f"legacy lease is not live ({freshness.get('status')}): "
+                        f"{freshness.get('reason')}; rebinding is not a recovery "
+                        "path for a lapsed lease"
+                    ],
+                    freshness=freshness,
+                )
+
+            policy = lease_policy.policy_for(lease_task_class(lock))
+            expires = current + timedelta(minutes=policy.initial_ttl_minutes)
+            session_id = mint_task_session_id(lease_task_class(lock))
+            record = dict(lock)
+            lease = dict(record.get("work_lease") or {})
+            legacy_origin = {
+                "created_at": lease.get("created_at"),
+                "expires_at": lease.get("expires_at"),
+                "last_heartbeat_at": lease.get("last_heartbeat_at"),
+                "lifecycle": lease_policy.LIFECYCLE_LEGACY,
+            }
+            lease["lifecycle_version"] = lease_policy.LIFECYCLE_HEARTBEAT_V1
+            lease["task_session_id"] = session_id
+            lease["created_at"] = _format_lease_timestamp(current)
+            lease["last_heartbeat_at"] = _format_lease_timestamp(current)
+            lease["expires_at"] = _format_lease_timestamp(expires)
+            lease["heartbeat_count"] = 1
+            record["work_lease"] = lease
+            record["legacy_rebind"] = {
+                "rebound_at": _format_lease_timestamp(current),
+                "task_session_id": session_id,
+                "prior_generation": current_generation,
+                "legacy_origin": legacy_origin,
+                "reason": (
+                    "legacy lock rebound into the heartbeat lifecycle by its exact "
+                    "recorded owner"
+                ),
+            }
+            record["lock_generation"] = current_generation + 1
+            save_lock_file(path, record)
+    except LockContentionError as exc:
+        return _refusal([f"issue #{issue_number} lock contention: {exc} (fail closed)"])
+
+    return {
+        "success": True,
+        "performed": True,
+        "issue_number": issue_number,
+        "task_session_id": session_id,
+        "lock_generation": record["lock_generation"],
+        "prior_generation": current_generation,
+        "lifecycle": lease_policy.LIFECYCLE_HEARTBEAT_V1,
+        "legacy_rebind": record["legacy_rebind"],
+        "expires_at": lease["expires_at"],
+        "last_heartbeat_at": lease["last_heartbeat_at"],
+        "lock_file_path": path,
+        "freshness": assess_lock_freshness(record, now=current),
+    }
+
+
 def read_session_issue_lock(lock_dir: str | None = None) -> dict[str, Any] | None:
     root = (lock_dir or default_lock_dir()).strip()
     pointer = read_lock_file(session_pointer_path(root))
@@ -336,6 +673,16 @@ def _parse_lease_timestamp(value: str | None) -> datetime | None:
         return None
 
 
+def _format_lease_timestamp(value: datetime) -> str:
+    """Serialize a lease timestamp in the durable ``...Z`` form already on disk."""
+    return (
+        value.astimezone(timezone.utc)
+        .replace(microsecond=0)
+        .isoformat()
+        .replace("+00:00", "Z")
+    )
+
+
 def lease_expires_at(lock: dict[str, Any] | None) -> datetime | None:
     if not lock:
         return None
@@ -356,60 +703,216 @@ def is_lease_live(lock: dict[str, Any] | None, *, now: datetime | None = None) -
     return assess_lock_freshness(lock, now=now)["live"]
 
 
+def lease_task_class(lock_data: dict[str, Any] | None) -> str:
+    """Policy task class for a durable lock; author work when unrecorded."""
+    lease = lock_data.get("work_lease") if isinstance(lock_data, dict) else None
+    if isinstance(lease, dict):
+        recorded = str(lease.get("operation_type") or "").strip()
+        if recorded:
+            return recorded
+    return AUTHOR_ISSUE_WORK_LEASE
+
+
+def lease_lifecycle_version(lock_data: dict[str, Any] | None) -> str:
+    """Read the durable lifecycle marker (#790 AC-N8).
+
+    The marker is the *only* discriminator between a heartbeat-lifecycle lease
+    and a legacy one. Timestamps are deliberately not consulted: a lock minted
+    before this lifecycle existed has ``last_heartbeat_at == created_at``
+    forever, and reading that equality as "recently heartbeated" would treat
+    every never-heartbeated legacy lock as fresh — the precise inversion AC-N8
+    forbids. A newly minted heartbeat lease also has the two equal, so the
+    equality carries no information in either direction.
+    """
+    lease = lock_data.get("work_lease") if isinstance(lock_data, dict) else None
+    if isinstance(lease, dict):
+        recorded = str(lease.get("lifecycle_version") or "").strip()
+        if recorded:
+            return recorded
+    return lease_policy.LIFECYCLE_LEGACY
+
+
+def is_legacy_lease(lock_data: dict[str, Any] | None) -> bool:
+    """True when a lock predates the shared heartbeat lifecycle."""
+    return lease_lifecycle_version(lock_data) != lease_policy.LIFECYCLE_HEARTBEAT_V1
+
+
+def lease_task_session_id(lock_data: dict[str, Any] | None) -> str:
+    """Recorded per-task session identifier, or empty for a legacy lock."""
+    lease = lock_data.get("work_lease") if isinstance(lock_data, dict) else None
+    if isinstance(lease, dict):
+        return str(lease.get("task_session_id") or "").strip()
+    return ""
+
+
+def mint_task_session_id(task_class: str = AUTHOR_ISSUE_WORK_LEASE) -> str:
+    """Mint an ownership key for one task (#790 AC-N1).
+
+    Deliberately contains no process identifier. The recorded PID belongs to the
+    long-lived MCP daemon, which outlives any individual task and is reused by
+    every task it serves, so PID digits cannot identify *which* task holds a
+    claim. The PID is still recorded alongside this value as evidence.
+    """
+    prefix = _sanitize_segment(str(task_class or AUTHOR_ISSUE_WORK_LEASE))
+    return f"{prefix}-{uuid.uuid4().hex[:16]}"
+
+
+def _lease_heartbeat_at(lock_data: dict[str, Any] | None) -> datetime | None:
+    lease = lock_data.get("work_lease") if isinstance(lock_data, dict) else None
+    heartbeat_at = None
+    if isinstance(lock_data, dict):
+        heartbeat_at = _parse_lease_timestamp(lock_data.get("last_heartbeat_at"))
+    if heartbeat_at is None and isinstance(lease, dict):
+        heartbeat_at = _parse_lease_timestamp(lease.get("last_heartbeat_at"))
+    return heartbeat_at
+
+
 def assess_lock_freshness(
     lock_data: dict[str, Any] | None,
     *,
     now: datetime | None = None,
 ) -> dict[str, Any]:
-    """Classify a lock as live, expired, stale, or absent."""
+    """Classify a lock as live, expired, stale, or absent.
+
+    #790 Slice A makes the heartbeat load-bearing. Before this change
+    ``last_heartbeat_at`` was parsed and then never consulted: liveness was
+    decided entirely by the absolute ``expires_at`` and by PID liveness, and
+    since the recorded PID is the long-lived MCP daemon, an abandoned author
+    task stayed "live" for the full four-hour TTL.
+
+    Two rules govern the rewrite:
+
+    * **An alive PID never establishes freshness** (AC-N2). It proves the daemon
+      is up, nothing about the task. It is recorded as evidence and no branch
+      returns ``live`` because of it.
+    * **A dead PID still corroborates staleness.** The dead-PID band is
+      unchanged and still precedes every heartbeat evaluation, so #753
+      dead-session recovery keys on exactly the classification it always did.
+
+    Legacy leases (AC-N8) keep their recorded absolute expiry and are never
+    evaluated against the short heartbeat grace, so deploying this change cannot
+    make an existing claim instantly reclaimable.
+    """
     current = _lease_now(now)
     if not lock_data:
         return {
-            "status": "absent",
+            "status": STATUS_ABSENT,
             "live": False,
             "stale": False,
             "reason": "no lock record",
         }
 
-    expires_at = lease_expires_at(lock_data)
     lease = lock_data.get("work_lease")
-    heartbeat_at = _parse_lease_timestamp(lock_data.get("last_heartbeat_at"))
+    expires_at = lease_expires_at(lock_data)
-    if heartbeat_at is None and isinstance(lease, dict):
+    heartbeat_at = _lease_heartbeat_at(lock_data)
-        heartbeat_at = _parse_lease_timestamp(lease.get("last_heartbeat_at"))
+    created_at = (
+        _parse_lease_timestamp(lease.get("created_at"))
+        if isinstance(lease, dict)
+        else None
+    )
 
     pid = lock_data.get("session_pid")
     if pid is None:
         pid = lock_data.get("pid")
+    # Evidence only. Never consulted to grant liveness (AC-N2).
     pid_alive = is_process_alive(pid) if pid is not None else False
 
-    if expires_at and expires_at <= current:
+    lifecycle = lease_lifecycle_version(lock_data)
-        return {
+    legacy = lifecycle != lease_policy.LIFECYCLE_HEARTBEAT_V1
-            "status": "expired",
+    policy = lease_policy.policy_for(lease_task_class(lock_data))
-            "live": False,
-            "stale": True,
-            "reason": f"lease expired at {expires_at.isoformat()}",
-            "pid_alive": pid_alive,
-        }
 
-    if pid is not None and not pid_alive:
+    evidence: dict[str, Any] = {
-        return {
-            "status": "stale",
-            "live": False,
-            "stale": True,
-            "reason": f"owner pid {pid} is not alive",
-            "pid_alive": False,
-        }
-
-    return {
-        "status": "live",
-        "live": True,
-        "stale": False,
-        "reason": "lock heartbeat and lease are fresh",
         "pid_alive": pid_alive,
+        "lifecycle": lifecycle,
+        "legacy_lease": legacy,
+        "task_session_id": lease_task_session_id(lock_data) or None,
         "heartbeat_at": heartbeat_at.isoformat() if heartbeat_at else None,
         "expires_at": expires_at.isoformat() if expires_at else None,
     }
 
+    def _result(status: str, *, live: bool, reason: str, **extra: Any) -> dict[str, Any]:
+        return {
+            "status": status,
+            "live": live,
+            "stale": not live and status != STATUS_ABSENT,
+            "reason": reason,
+            **evidence,
+            **extra,
+        }
+
+    if legacy:
+        # AC-N8: the preserved absolute expiry is the only clock for a lock
+        # written before task-session heartbeats existed.
+        if expires_at and expires_at <= current:
+            return _result(
+                STATUS_EXPIRED,
+                live=False,
+                reason=f"lease expired at {expires_at.isoformat()}",
+            )
+        if pid is not None and not pid_alive:
+            return _result(
+                STATUS_STALE, live=False, reason=f"owner pid {pid} is not alive"
+            )
+        return _result(
+            STATUS_LIVE,
+            live=True,
+            reason=(
+                "legacy lease is within its recorded absolute expiry; the "
+                "heartbeat grace does not apply retroactively"
+            ),
+            legacy_expiry_preserved=True,
+        )
+
+    # ── Heartbeat lifecycle ──
+    if pid is not None and not pid_alive:
+        # Unchanged dead-PID band: #753 recovery depends on this exact status.
+        return _result(STATUS_STALE, live=False, reason=f"owner pid {pid} is not alive")
+
+    if heartbeat_at is None:
+        # Contradictory: a heartbeat lease must carry a heartbeat. Fail closed.
+        return _result(
+            STATUS_STALE_MISSED_HEARTBEAT,
+            live=False,
+            reason=(
+                f"lease declares lifecycle '{lifecycle}' but records no "
+                "last_heartbeat_at (fail closed)"
+            ),
+        )
+
+    if policy.absolute_cap_hours and created_at is not None:
+        cap_at = created_at + timedelta(hours=policy.absolute_cap_hours)
+        if cap_at <= current:
+            return _result(
+                STATUS_STALE_ABSOLUTE_CAP,
+                live=False,
+                reason=(
+                    f"lease exceeded its {policy.absolute_cap_hours}h absolute cap "
+                    f"at {cap_at.isoformat()}; canonical re-adoption is required"
+                ),
+                absolute_cap_at=cap_at.isoformat(),
+            )
+
+    grace_at = heartbeat_at + timedelta(minutes=policy.missed_heartbeat_grace_minutes)
+    if grace_at <= current or (expires_at is not None and expires_at <= current):
+        return _result(
+            STATUS_STALE_MISSED_HEARTBEAT,
+            live=False,
+            reason=(
+                f"no valid heartbeat since {heartbeat_at.isoformat()}; the "
+                f"{policy.missed_heartbeat_grace_minutes}min grace lapsed at "
+                f"{grace_at.isoformat()}"
+            ),
+            missed_heartbeat_since=grace_at.isoformat(),
+        )
+
+    warning_at = heartbeat_at + timedelta(minutes=policy.stale_warning_minutes)
+    return _result(
+        STATUS_LIVE,
+        live=True,
+        reason="lease heartbeat is fresh within the configured grace",
+        heartbeat_warning=warning_at <= current,
+    )
+
 
 def _same_realpath(left: str | None, right: str | None) -> bool:
     if not left or not right:
@@ -446,6 +949,27 @@ def assess_expired_lock_reclaim(
             "reasons": ["lock is still live; cannot reclaim (fail closed)"],
             "freshness": freshness,
         }
+    status = str(freshness.get("status") or "")
+    if status in (STATUS_STALE_MISSED_HEARTBEAT, STATUS_STALE_ABSOLUTE_CAP):
+        # #790: under the heartbeat lifecycle the heartbeat *is* the liveness
+        # proof, so a session that stopped heartbeating past its grace has
+        # released its claim by definition. Requiring a dead PID on top of that
+        # would reinstate the original defect — the recorded PID is the shared
+        # daemon, which stays alive across every abandoned task it ever served.
+        #
+        # This band is unreachable for a legacy lease (AC-N8), so no lock
+        # written before this lifecycle can be reclaimed by this path.
+        return {
+            "reclaim_allowed": True,
+            "reasons": [
+                f"heartbeat-lifecycle lease is {status}: {freshness.get('reason')}"
+            ],
+            "freshness": freshness,
+            "prior_branch": existing_lock.get("branch_name"),
+            "prior_worktree": existing_lock.get("worktree_path"),
+            "prior_pid": existing_lock.get("session_pid") or existing_lock.get("pid"),
+            "prior_task_session_id": lease_task_session_id(existing_lock) or None,
+        }
     pid = existing_lock.get("session_pid")
     if pid is None:
         pid = existing_lock.get("pid")

lease_policy.py

@@ -0,0 +1,212 @@
+"""Central lease policy configuration (#790 Slice A, AC-N7).
+
+The single authoritative source for every lease duration in the project. Before
+this module the numbers were scattered: a four-hour author TTL was declared
+twice (``issue_lock_store`` and ``gitea_mcp_server``), the reviewer/merger
+sliding window lived in ``reviewer_pr_lease``, the conflict-fix window in
+``pr_work_lease``, and the control-plane default in ``control_plane_db``.
+Nothing tied them together, so tuning one class silently diverged from the
+others and no reader could answer "how long does a lease live?" without
+grepping four files.
+
+AC-N7 requires that this configuration exist *before* the first heartbeat and
+TTL behavior that reads from it, so it ships in Slice A rather than trailing the
+code it governs.
+
+Deliberate boundaries:
+
+* **Declaration is not rewiring.** Every task class is declared here, but only
+  those with ``heartbeat_lifecycle_active`` were migrated onto the shared
+  heartbeat lifecycle in Slice A — currently ``author_issue_work`` alone.
+  Reviewer, merger, and conflict-fix leases keep their own existing behavior
+  until Slice C moves them; their numbers are recorded here so the two cannot
+  drift apart unnoticed, and ``tests/test_issue_790_lease_policy.py`` asserts
+  the recorded values still equal the constants those modules use.
+* **No policy decision lives here.** This module answers "how long", never "may
+  this session proceed". Freshness, reclaim, and renewal dispositions stay in
+  ``issue_lock_store``.
+"""
+
+from __future__ import annotations
+
+import os
+from dataclasses import dataclass
+from typing import Any
+
+# Task classes. Only the first is migrated onto the shared lifecycle in Slice A.
+TASK_CLASS_AUTHOR_ISSUE_WORK = "author_issue_work"
+TASK_CLASS_REVIEWER_PR = "reviewer_pr"
+TASK_CLASS_MERGER_PR = "merger_pr"
+TASK_CLASS_CONFLICT_FIX = "conflict_fix"
+
+# Durable marker for a lease minted under the shared heartbeat lifecycle.
+#
+# #790 AC-N8: this explicit marker — never a timestamp comparison — is what
+# distinguishes a heartbeat-lifecycle lease from a legacy one. A lock written
+# before this lifecycle existed carries no marker and reads as
+# ``LIFECYCLE_LEGACY``.
+LIFECYCLE_HEARTBEAT_V1 = "heartbeat-v1"
+LIFECYCLE_LEGACY = "legacy"
+
+_ENV_PREFIX = "GITEA_LEASE_POLICY"
+
+
+@dataclass(frozen=True)
+class LeasePolicy:
+    """Durations governing one task class.
+
+    All intervals are minutes except ``absolute_cap_hours``. ``None`` for the
+    cap means the class has no maximum continuous duration.
+    """
+
+    task_class: str
+    initial_ttl_minutes: float
+    heartbeat_cadence_minutes: float
+    stale_warning_minutes: float
+    missed_heartbeat_grace_minutes: float
+    absolute_cap_hours: float | None
+    recovery_grace_minutes: float
+    terminal_race_drain_minutes: float
+    terminal_retirement_eligible: bool
+    heartbeat_lifecycle_active: bool
+
+
+# Defaults. ``author_issue_work`` adopts the reviewer window proven by #747
+# rather than inventing new numbers: a lease expires 10 minutes after its last
+# valid heartbeat, warns at half that, and an actively heartbeating session is
+# never evicted. The prior value was a fixed four hours (240 minutes) that no
+# heartbeat could shorten — the defect this issue exists to correct.
+_DEFAULTS: dict[str, LeasePolicy] = {
+    TASK_CLASS_AUTHOR_ISSUE_WORK: LeasePolicy(
+        task_class=TASK_CLASS_AUTHOR_ISSUE_WORK,
+        initial_ttl_minutes=10.0,
+        heartbeat_cadence_minutes=2.0,
+        stale_warning_minutes=5.0,
+        missed_heartbeat_grace_minutes=10.0,
+        absolute_cap_hours=8.0,
+        recovery_grace_minutes=10.0,
+        terminal_race_drain_minutes=2.0,
+        terminal_retirement_eligible=True,
+        heartbeat_lifecycle_active=True,
+    ),
+    # Declared, not rewired. These mirror reviewer_pr_lease.LEASE_TTL_MINUTES
+    # and STALE_WARNING_MINUTES; Slice C migrates the call sites.
+    TASK_CLASS_REVIEWER_PR: LeasePolicy(
+        task_class=TASK_CLASS_REVIEWER_PR,
+        initial_ttl_minutes=10.0,
+        heartbeat_cadence_minutes=2.0,
+        stale_warning_minutes=5.0,
+        missed_heartbeat_grace_minutes=10.0,
+        absolute_cap_hours=None,
+        recovery_grace_minutes=10.0,
+        terminal_race_drain_minutes=2.0,
+        terminal_retirement_eligible=False,
+        heartbeat_lifecycle_active=False,
+    ),
+    TASK_CLASS_MERGER_PR: LeasePolicy(
+        task_class=TASK_CLASS_MERGER_PR,
+        initial_ttl_minutes=10.0,
+        heartbeat_cadence_minutes=2.0,
+        stale_warning_minutes=5.0,
+        missed_heartbeat_grace_minutes=10.0,
+        absolute_cap_hours=None,
+        recovery_grace_minutes=10.0,
+        terminal_race_drain_minutes=2.0,
+        terminal_retirement_eligible=False,
+        heartbeat_lifecycle_active=False,
+    ),
+    # Mirrors pr_work_lease.DEFAULT_CONFLICT_FIX_TTL_MINUTES. Deliberately left
+    # at its current window; shortening it is Slice C's call, not this slice's.
+    TASK_CLASS_CONFLICT_FIX: LeasePolicy(
+        task_class=TASK_CLASS_CONFLICT_FIX,
+        initial_ttl_minutes=120.0,
+        heartbeat_cadence_minutes=2.0,
+        stale_warning_minutes=5.0,
+        missed_heartbeat_grace_minutes=10.0,
+        absolute_cap_hours=None,
+        recovery_grace_minutes=10.0,
+        terminal_race_drain_minutes=2.0,
+        terminal_retirement_eligible=False,
+        heartbeat_lifecycle_active=False,
+    ),
+}
+
+_NUMERIC_FIELDS = (
+    "initial_ttl_minutes",
+    "heartbeat_cadence_minutes",
+    "stale_warning_minutes",
+    "missed_heartbeat_grace_minutes",
+    "absolute_cap_hours",
+    "recovery_grace_minutes",
+    "terminal_race_drain_minutes",
+)
+
+
+def env_var_name(task_class: str, field: str) -> str:
+    """Environment variable that overrides one field of one task class."""
+    return f"{_ENV_PREFIX}_{task_class.upper()}_{field.upper()}"
+
+
+def _override(task_class: str, field: str, default: float | None) -> float | None:
+    """Read one override, falling back to *default* on anything unusable.
+
+    A malformed or non-positive override is ignored rather than raised: a typo
+    in an environment variable must not be able to mint a zero-length lease that
+    makes every claim instantly reclaimable, nor crash the server at import.
+    """
+    raw = (os.environ.get(env_var_name(task_class, field)) or "").strip()
+    if not raw:
+        return default
+    try:
+        value = float(raw)
+    except (TypeError, ValueError):
+        return default
+    if value <= 0:
+        return default
+    return value
+
+
+def policy_for(task_class: str) -> LeasePolicy:
+    """Return the effective policy for *task_class*.
+
+    Unknown task classes fall back to the author policy, which is the most
+    conservative migrated class, rather than raising — a new caller must never
+    be able to crash a lock write by naming a class this table has not learned.
+    """
+    key = str(task_class or "").strip() or TASK_CLASS_AUTHOR_ISSUE_WORK
+    base = _DEFAULTS.get(key) or _DEFAULTS[TASK_CLASS_AUTHOR_ISSUE_WORK]
+    resolved = {
+        field: _override(base.task_class, field, getattr(base, field))
+        for field in _NUMERIC_FIELDS
+    }
+    if all(resolved[field] == getattr(base, field) for field in _NUMERIC_FIELDS):
+        return base
+    return LeasePolicy(
+        task_class=base.task_class,
+        terminal_retirement_eligible=base.terminal_retirement_eligible,
+        heartbeat_lifecycle_active=base.heartbeat_lifecycle_active,
+        **resolved,
+    )
+
+
+def known_task_classes() -> tuple[str, ...]:
+    """Every declared task class, migrated or not."""
+    return tuple(_DEFAULTS)
+
+
+def describe(task_class: str) -> dict[str, Any]:
+    """Serializable view of a policy, for audit records and tool payloads."""
+    policy = policy_for(task_class)
+    return {
+        "task_class": policy.task_class,
+        "initial_ttl_minutes": policy.initial_ttl_minutes,
+        "heartbeat_cadence_minutes": policy.heartbeat_cadence_minutes,
+        "stale_warning_minutes": policy.stale_warning_minutes,
+        "missed_heartbeat_grace_minutes": policy.missed_heartbeat_grace_minutes,
+        "absolute_cap_hours": policy.absolute_cap_hours,
+        "recovery_grace_minutes": policy.recovery_grace_minutes,
+        "terminal_race_drain_minutes": policy.terminal_race_drain_minutes,
+        "terminal_retirement_eligible": policy.terminal_retirement_eligible,
+        "heartbeat_lifecycle_active": policy.heartbeat_lifecycle_active,
+        "lifecycle_version": LIFECYCLE_HEARTBEAT_V1,
+    }

task_capability_map.py

@@ -32,6 +32,15 @@ TASK_CAPABILITY_MAP: dict[str, dict[str, str]] = {
         "permission": "gitea.issue.comment",
         "role": "author",
     },
+    # #790 Slice A: prove an owned author lease is still active. Strictly
+    # narrower than lock_issue — it can only slide a lease this exact session
+    # already owns, never acquire, take over, or revive one — so it gates on the
+    # same authority rather than introducing an operation name that every
+    # already-configured author profile would be missing.
+    "heartbeat_issue_lock": {
+        "permission": "gitea.issue.comment",
+        "role": "author",
+    },
     "set_issue_labels": {
         "permission": "gitea.issue.comment",
         "role": "author",

tests/test_issue_790_heartbeat_mcp_path.py

@@ -0,0 +1,444 @@
+"""Task heartbeat through the native MCP author path (#790 Slice A, AC-N6).
+
+Assessor-level coverage is not sufficient here, and this project has already
+paid for learning that: in review #499 on PR #791 the #760 renewal waiver was
+computed correctly and then *discarded* at two later gates, so every real
+renewal still failed while the unit suite stayed green. AC-N6 exists because of
+that, and requires driving the real tools against a real git repository and a
+real durable lock file, composing the gates in production order.
+
+These tests therefore call ``gitea_lock_issue`` and
+``gitea_heartbeat_issue_lock`` themselves and assert on what lands on disk,
+never on an assessor's return value alone.
+"""
+
+from __future__ import annotations
+
+import os
+import subprocess
+import sys
+import tempfile
+import unittest
+from datetime import datetime, timedelta, timezone
+from unittest.mock import patch
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
+
+from mutation_profile_fixture import shared_mutation_env  # noqa: E402
+
+import issue_lock_provenance  # noqa: E402
+import issue_lock_store  # noqa: E402
+import lease_policy  # noqa: E402
+import mcp_server  # noqa: E402
+
+ISSUE = 9791
+BRANCH = f"fix/issue-{ISSUE}-heartbeat-mcp"
+IDENTITY = "example-user"
+PROFILE = "test-author-prgs"
+ORG = "Scaled-Tech-Consulting"
+REPO = "Gitea-Tools"
+
+
+def _ts(moment: datetime) -> str:
+    return (
+        moment.astimezone(timezone.utc)
+        .replace(microsecond=0)
+        .isoformat()
+        .replace("+00:00", "Z")
+    )
+
+
+class _HeartbeatMcpBase(unittest.TestCase):
+    """Real git repo plus a real durable lock, driven through the real tools."""
+
+    def setUp(self):
+        self.lock_dir = tempfile.TemporaryDirectory()
+        self.addCleanup(self.lock_dir.cleanup)
+        self.repo = tempfile.mkdtemp(prefix="issue790-mcp-")
+        self.addCleanup(lambda: subprocess.run(["rm", "-rf", self.repo], check=False))
+        self._init_worktree()
+        self.remotes = patch.dict(
+            mcp_server.REMOTES,
+            {"prgs": {"host": "gitea.prgs.cc", "org": ORG, "repo": REPO}},
+        )
+        self.remotes.start()
+        self.addCleanup(patch.stopall)
+        mcp_server._IDENTITY_CACHE.clear()
+
+    def _git(self, *args):
+        return subprocess.run(
+            ["git", "-C", self.repo, *args], capture_output=True, text=True, check=True
+        )
+
+    def _init_worktree(self):
+        self._git("init", "-q", "-b", "master")
+        self._git("config", "user.email", "[email protected]")
+        self._git("config", "user.name", "Test")
+        with open(os.path.join(self.repo, "seed.txt"), "w") as fh:
+            fh.write("seed\n")
+        self._git("add", "seed.txt")
+        self._git("commit", "-q", "-m", "seed")
+        self.base_sha = self._git("rev-parse", "HEAD").stdout.strip()
+        # A fresh claim starts base-equivalent, which is the ordinary first-lock
+        # shape and exercises assess_issue_lock_worktree on its normal path.
+        self._git("checkout", "-q", "-b", BRANCH)
+        self.head_sha = self.base_sha
+        self.worktree = os.path.realpath(self.repo)
+
+    def _lock_path(self):
+        return issue_lock_store.lock_file_path(
+            remote="prgs",
+            org=ORG,
+            repo=REPO,
+            issue_number=ISSUE,
+            lock_dir=self.lock_dir.name,
+        )
+
+    def _tool_env(self):
+        env = shared_mutation_env(
+            PROFILE, include_example_repo=True, GITEA_ISSUE_LOCK_DIR=self.lock_dir.name
+        )
+        env["GITEA_ISSUE_LOCK_DIR"] = self.lock_dir.name
+        return env
+
+    def _git_state(self, *, porcelain="", base_equivalent=True):
+        return {
+            "current_branch": BRANCH,
+            "porcelain_status": porcelain,
+            "base_equivalent": base_equivalent,
+            "head_sha": self.head_sha,
+            "inspected_git_root": self.worktree,
+            "base_branch": "master",
+        }
+
+    def run_lock_issue(
+        self,
+        *,
+        branch_entries=None,
+        open_prs=None,
+        git_state=None,
+        identity=IDENTITY,
+        profile=PROFILE,
+    ):
+        branch_entries = branch_entries if branch_entries is not None else []
+        open_prs = open_prs if open_prs is not None else []
+        git_state = git_state or self._git_state()
+        env = self._tool_env()
+        with patch(
+            "mcp_server.api_get_all", return_value=list(branch_entries)
+        ), patch(
+            "mcp_server._list_open_pulls", return_value=list(open_prs)
+        ), patch(
+            "mcp_server.get_auth_header", return_value="token x"
+        ), patch(
+            "mcp_server._work_lease_claimant",
+            return_value={"username": identity, "profile": profile},
+        ), patch(
+            "mcp_server.issue_lock_worktree.read_worktree_git_state",
+            return_value=git_state,
+        ), patch(
+            "mcp_server.issue_duplicate_context_fetcher",
+            side_effect=lambda h, o, r, auth, issue_number: (
+                list(open_prs),
+                [b.get("name") for b in branch_entries if isinstance(b, dict)],
+                {"status": "not_claimed"},
+            ),
+        ), patch.dict(os.environ, env, clear=True):
+            os.environ["GITEA_ISSUE_LOCK_DIR"] = self.lock_dir.name
+            return mcp_server.gitea_lock_issue(
+                issue_number=ISSUE,
+                branch_name=BRANCH,
+                remote="prgs",
+                worktree_path=self.worktree,
+            )
+
+    def run_heartbeat(
+        self, *, task_session_id, identity=IDENTITY, profile=PROFILE, **kwargs
+    ):
+        env = self._tool_env()
+        with patch(
+            "mcp_server._work_lease_claimant",
+            return_value={"username": identity, "profile": profile},
+        ), patch("mcp_server.get_auth_header", return_value="token x"), patch.dict(
+            os.environ, env, clear=True
+        ):
+            os.environ["GITEA_ISSUE_LOCK_DIR"] = self.lock_dir.name
+            return mcp_server.gitea_heartbeat_issue_lock(
+                issue_number=ISSUE,
+                branch_name=kwargs.pop("branch_name", BRANCH),
+                task_session_id=task_session_id,
+                remote="prgs",
+                worktree_path=kwargs.pop("worktree_path", self.worktree),
+                **kwargs,
+            )
+
+    def write_legacy_lock(self, *, hours_old: float = 3.0, ttl_hours: float = 4.0):
+        """A durable lock in the shape the store wrote before this slice."""
+        now = datetime.now(timezone.utc)
+        claimant = {"username": IDENTITY, "profile": PROFILE}
+        created = now - timedelta(hours=hours_old)
+        record = {
+            "issue_number": ISSUE,
+            "branch_name": BRANCH,
+            "remote": "prgs",
+            "org": ORG,
+            "repo": REPO,
+            "worktree_path": self.worktree,
+            "session_pid": os.getpid(),
+            "pid": os.getpid(),
+            "lock_generation": 1,
+            "work_lease": {
+                "operation_type": issue_lock_store.AUTHOR_ISSUE_WORK_LEASE,
+                "issue_number": ISSUE,
+                "pr_number": None,
+                "branch": BRANCH,
+                "worktree_path": self.worktree,
+                "claimant": claimant,
+                "created_at": _ts(created),
+                # The legacy signature: never advanced past creation.
+                "last_heartbeat_at": _ts(created),
+                "expires_at": _ts(created + timedelta(hours=ttl_hours)),
+            },
+            "lock_provenance": issue_lock_provenance.build_sanctioned_lock_provenance(
+                tool="gitea_lock_issue", claimant=claimant
+            ),
+        }
+        path = self._lock_path()
+        record["lock_file_path"] = path
+        issue_lock_store.save_lock_file(path, record)
+        return record
+
+
+class TestLockIssueMintsTheLifecycle(_HeartbeatMcpBase):
+    """Durable lock creation and read-back through the real tool."""
+
+    def test_native_lock_writes_the_marker_and_a_task_session_id(self):
+        result = self.run_lock_issue()
+        self.assertTrue(result["success"], result)
+
+        written = issue_lock_store.read_lock_file(result["lock_file_path"])
+        lease = written["work_lease"]
+        self.assertEqual(
+            lease["lifecycle_version"], lease_policy.LIFECYCLE_HEARTBEAT_V1
+        )
+        self.assertTrue(lease["task_session_id"])
+        self.assertFalse(issue_lock_store.is_legacy_lease(written))
+        # AC-N1: the ownership key is not the daemon pid, which is recorded
+        # separately as evidence.
+        self.assertNotIn(str(written["session_pid"]), lease["task_session_id"])
+        self.assertEqual(written["session_pid"], os.getpid())
+
+    def test_native_lease_uses_the_policy_window_not_four_hours(self):
+        result = self.run_lock_issue()
+        lease = result["work_lease"]
+        created = datetime.fromisoformat(lease["created_at"].replace("Z", "+00:00"))
+        expires = datetime.fromisoformat(lease["expires_at"].replace("Z", "+00:00"))
+        policy = lease_policy.policy_for(lease_policy.TASK_CLASS_AUTHOR_ISSUE_WORK)
+        self.assertEqual(
+            (expires - created).total_seconds() / 60.0, policy.initial_ttl_minutes
+        )
+
+    def test_freshness_of_a_new_native_lock_is_live(self):
+        result = self.run_lock_issue()
+        self.assertEqual(
+            result["lock_freshness"]["status"], issue_lock_store.STATUS_LIVE
+        )
+        self.assertTrue(result["lock_freshness"]["live"])
+
+
+class TestHeartbeatThroughTheTool(_HeartbeatMcpBase):
+    def _lock_and_session(self):
+        result = self.run_lock_issue()
+        self.assertTrue(result["success"], result)
+        return result, result["work_lease"]["task_session_id"]
+
+    def test_heartbeat_slides_the_lease_and_advances_the_generation(self):
+        locked, session = self._lock_and_session()
+        before = issue_lock_store.read_lock_file(locked["lock_file_path"])
+
+        beat = self.run_heartbeat(task_session_id=session)
+
+        self.assertTrue(beat["success"], beat)
+        self.assertEqual(beat["operation"], "heartbeat")
+        after = issue_lock_store.read_lock_file(locked["lock_file_path"])
+        self.assertGreater(
+            issue_lock_store.lock_generation(after),
+            issue_lock_store.lock_generation(before),
+        )
+        self.assertGreaterEqual(
+            after["work_lease"]["expires_at"], before["work_lease"]["expires_at"]
+        )
+        self.assertEqual(after["work_lease"]["heartbeat_count"], 2)
+
+    def test_heartbeat_evidence_survives_the_downstream_mutation_gate(self):
+        """The #499 F2 lesson, applied.
+
+        A sanction that is computed and then discarded downstream is worthless.
+        After a heartbeat the lock must still satisfy the gate every author
+        mutation runs through.
+        """
+        locked, session = self._lock_and_session()
+        self.run_heartbeat(task_session_id=session)
+
+        written = issue_lock_store.read_lock_file(locked["lock_file_path"])
+        verdict = issue_lock_store.verify_lock_for_mutation(
+            written,
+            issue_number=ISSUE,
+            branch_name=BRANCH,
+            worktree_path=self.worktree,
+        )
+        self.assertTrue(verdict["proven"], verdict)
+        self.assertFalse(verdict["block"])
+
+    def _duplicate_gate(self, *, open_prs, branches):
+        env = self._tool_env()
+        with patch("mcp_server.get_auth_header", return_value="token x"), patch(
+            "mcp_server.issue_duplicate_context_fetcher",
+            side_effect=lambda h, o, r, auth, issue_number: (
+                list(open_prs),
+                list(branches),
+                {"status": "not_claimed"},
+            ),
+        ), patch.dict(os.environ, env, clear=True):
+            os.environ["GITEA_ISSUE_LOCK_DIR"] = self.lock_dir.name
+            return mcp_server.gitea_assess_work_issue_duplicate(
+                issue_number=ISSUE, branch_name=BRANCH, remote="prgs"
+            )
+
+    def test_heartbeat_does_not_change_the_duplicate_gate_verdict(self):
+        """The gate must be invariant under heartbeating.
+
+        The point is not that the gate passes — with a linked open PR at the
+        lock phase it correctly blocks (#400), heartbeat or not. The property
+        that matters is that sliding a lease neither loosens the gate nor
+        corrupts the lock state it reads: the verdict before and after a
+        heartbeat must be identical, for both the clear and the blocking shape.
+        """
+        _, session = self._lock_and_session()
+        linked = [{"number": 4242, "head": {"ref": BRANCH, "sha": self.head_sha}}]
+
+        clear_before = self._duplicate_gate(open_prs=[], branches=[])
+        blocked_before = self._duplicate_gate(open_prs=linked, branches=[BRANCH])
+
+        self.assertTrue(self.run_heartbeat(task_session_id=session)["success"])
+
+        clear_after = self._duplicate_gate(open_prs=[], branches=[])
+        blocked_after = self._duplicate_gate(open_prs=linked, branches=[BRANCH])
+
+        self.assertEqual(clear_before["outcome"], clear_after["outcome"])
+        self.assertFalse(clear_after["block"])
+        self.assertEqual(blocked_before["outcome"], blocked_after["outcome"])
+        self.assertTrue(blocked_after["block"])
+        self.assertEqual(blocked_after["linked_open_pr"], 4242)
+
+    def test_foreign_session_id_is_refused_through_the_tool(self):
+        self._lock_and_session()
+        beat = self.run_heartbeat(task_session_id="author_issue_work-ffffffffffffffff")
+        self.assertFalse(beat["success"])
+        self.assertIn("task_session_id does not match", " ".join(beat["reasons"]))
+
+    def test_stale_generation_is_refused_through_the_tool(self):
+        locked, session = self._lock_and_session()
+        current = issue_lock_store.lock_generation(
+            issue_lock_store.read_lock_file(locked["lock_file_path"])
+        )
+        beat = self.run_heartbeat(
+            task_session_id=session, expected_generation=current + 5
+        )
+        self.assertFalse(beat["success"])
+        self.assertIn("generation changed", beat["reasons"][0])
+
+    def test_foreign_claimant_is_refused_through_the_tool(self):
+        _, session = self._lock_and_session()
+        beat = self.run_heartbeat(task_session_id=session, identity="someone-else")
+        self.assertFalse(beat["success"])
+
+    def test_heartbeat_cannot_acquire_a_missing_lock(self):
+        beat = self.run_heartbeat(task_session_id="author_issue_work-000000000000")
+        self.assertFalse(beat["success"])
+        self.assertIn("no durable lock", beat["reasons"][0])
+
+    def test_alive_pid_alone_does_not_keep_a_lease_live_through_the_tool(self):
+        """PID-only refusal, end to end.
+
+        The recorded pid is this live process. The lock is aged past its grace
+        with no heartbeat, so the tool must refuse to slide it and the durable
+        record must classify as a missed heartbeat rather than as live.
+        """
+        locked, session = self._lock_and_session()
+        record = issue_lock_store.read_lock_file(locked["lock_file_path"])
+        record["work_lease"]["last_heartbeat_at"] = _ts(
+            datetime.now(timezone.utc) - timedelta(minutes=30)
+        )
+        record["work_lease"]["expires_at"] = _ts(
+            datetime.now(timezone.utc) + timedelta(hours=2)
+        )
+        issue_lock_store.save_lock_file(locked["lock_file_path"], record)
+
+        self.assertTrue(issue_lock_store.is_process_alive(record["session_pid"]))
+        fresh = issue_lock_store.assess_lock_freshness(record)
+        self.assertEqual(
+            fresh["status"], issue_lock_store.STATUS_STALE_MISSED_HEARTBEAT
+        )
+        self.assertTrue(fresh["pid_alive"])
+
+        beat = self.run_heartbeat(task_session_id=session)
+        self.assertFalse(beat["success"])
+        self.assertIn("reclaimed", " ".join(beat["reasons"]))
+
+
+class TestLegacyLocksThroughTheTool(_HeartbeatMcpBase):
+    """AC-N8 end to end: protected on deployment, and rebindable."""
+
+    def test_legacy_lock_stays_protected_after_deployment(self):
+        record = self.write_legacy_lock(hours_old=3.0, ttl_hours=4.0)
+        fresh = issue_lock_store.assess_lock_freshness(record)
+        self.assertEqual(fresh["status"], issue_lock_store.STATUS_LIVE)
+        self.assertTrue(fresh["legacy_lease"])
+        self.assertTrue(fresh["legacy_expiry_preserved"])
+        # It had never heartbeated, so under the new grace alone it would be
+        # long gone; the preserved absolute expiry is what protects it.
+        self.assertEqual(
+            record["work_lease"]["created_at"],
+            record["work_lease"]["last_heartbeat_at"],
+        )
+
+    def test_tool_rebinds_a_legacy_lock_and_mints_a_first_heartbeat(self):
+        self.write_legacy_lock(hours_old=3.0, ttl_hours=4.0)
+
+        result = self.run_heartbeat(task_session_id=None)
+
+        self.assertTrue(result["success"], result)
+        self.assertEqual(result["operation"], "legacy_rebind")
+        self.assertTrue(result["task_session_id"])
+
+        written = issue_lock_store.read_lock_file(self._lock_path())
+        lease = written["work_lease"]
+        self.assertEqual(
+            lease["lifecycle_version"], lease_policy.LIFECYCLE_HEARTBEAT_V1
+        )
+        self.assertEqual(lease["heartbeat_count"], 1)
+        self.assertNotEqual(
+            lease["created_at"],
+            written["legacy_rebind"]["legacy_origin"]["created_at"],
+        )
+        self.assertFalse(issue_lock_store.is_legacy_lease(written))
+
+    def test_rebound_lock_then_heartbeats_through_the_tool(self):
+        self.write_legacy_lock(hours_old=3.0, ttl_hours=4.0)
+        rebound = self.run_heartbeat(task_session_id=None)
+        beat = self.run_heartbeat(task_session_id=rebound["task_session_id"])
+        self.assertTrue(beat["success"], beat)
+        self.assertEqual(beat["operation"], "heartbeat")
+        self.assertEqual(beat["heartbeat_count"], 2)
+
+    def test_rebind_refuses_a_foreign_owner_through_the_tool(self):
+        self.write_legacy_lock(hours_old=3.0, ttl_hours=4.0)
+        result = self.run_heartbeat(task_session_id=None, identity="someone-else")
+        self.assertFalse(result["success"])
+        self.assertEqual(result["operation"], "legacy_rebind")
+
+
+if __name__ == "__main__":
+    unittest.main()

tests/test_issue_790_lease_policy.py

@@ -0,0 +1,594 @@
+"""Central lease policy and load-bearing heartbeat freshness (#790 Slice A).
+
+Before this slice, ``issue_lock_store.assess_lock_freshness`` parsed
+``last_heartbeat_at`` and then never consulted it: liveness was decided by an
+absolute four-hour ``expires_at`` and by PID liveness. Because the recorded PID
+is the long-lived MCP daemon rather than the authoring task, an abandoned claim
+stayed "live" for the full four hours, and a claim whose work had already landed
+blocked reconciliation for just as long (Issue #787 / PR #789, and again Issue
+#760 / PR #791).
+
+These tests pin the corrected semantics, including the two asymmetries that are
+easy to lose in a refactor:
+
+* an **alive** PID must never make anything live (AC-N2), while
+* a **dead** PID must still mark a lease stale, because #753 dead-session
+  recovery keys on exactly that classification.
+
+Durable-state helpers here write real lock files through the real flock path;
+they are not mocks of the store.
+"""
+
+from __future__ import annotations
+
+import os
+import sys
+import tempfile
+import unittest
+from datetime import datetime, timedelta, timezone
+from unittest.mock import patch
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+
+import issue_lock_store  # noqa: E402
+import lease_policy  # noqa: E402
+import pr_work_lease  # noqa: E402
+import reviewer_pr_lease  # noqa: E402
+
+ISSUE = 9790
+BRANCH = f"fix/issue-{ISSUE}-heartbeat"
+IDENTITY = "example-user"
+PROFILE = "test-author-prgs"
+ORG = "Example-Org"
+REPO = "Example-Repo"
+REMOTE = "prgs"
+DEAD_PID = 2**22  # far above any live pid on a test host
+
+
+def _ts(moment: datetime) -> str:
+    return (
+        moment.astimezone(timezone.utc)
+        .replace(microsecond=0)
+        .isoformat()
+        .replace("+00:00", "Z")
+    )
+
+
+class _LockFixture(unittest.TestCase):
+    def setUp(self):
+        self.lock_dir = tempfile.TemporaryDirectory()
+        self.addCleanup(self.lock_dir.cleanup)
+        self.now = datetime.now(timezone.utc)
+        self.worktree = os.path.realpath(tempfile.mkdtemp(prefix="issue790-"))
+        self.addCleanup(patch.stopall)
+
+    def _path(self):
+        return issue_lock_store.lock_file_path(
+            remote=REMOTE,
+            org=ORG,
+            repo=REPO,
+            issue_number=ISSUE,
+            lock_dir=self.lock_dir.name,
+        )
+
+    def write_lock(
+        self,
+        *,
+        lifecycle: str | None = lease_policy.LIFECYCLE_HEARTBEAT_V1,
+        created_delta: timedelta = timedelta(minutes=1),
+        heartbeat_delta: timedelta = timedelta(minutes=1),
+        expires_delta: timedelta = timedelta(minutes=9),
+        pid: int | None = None,
+        task_session_id: str | None = "author_issue_work-aaaabbbbccccdddd",
+        generation: int = 1,
+        identity: str = IDENTITY,
+        profile: str = PROFILE,
+        branch: str = BRANCH,
+        worktree: str | None = None,
+    ) -> dict:
+        """Write a real durable lock and return the record.
+
+        Deltas are relative to ``self.now``; ``expires_delta`` is added, the
+        others subtracted, so "in the past" reads naturally at each call site.
+        """
+        lease: dict = {
+            "operation_type": issue_lock_store.AUTHOR_ISSUE_WORK_LEASE,
+            "issue_number": ISSUE,
+            "pr_number": None,
+            "branch": branch,
+            "worktree_path": worktree or self.worktree,
+            "claimant": {"username": identity, "profile": profile},
+            "created_at": _ts(self.now - created_delta),
+            "last_heartbeat_at": _ts(self.now - heartbeat_delta),
+            "expires_at": _ts(self.now + expires_delta),
+        }
+        if lifecycle is not None:
+            lease["lifecycle_version"] = lifecycle
+            if task_session_id is not None:
+                lease["task_session_id"] = task_session_id
+        pid_value = os.getpid() if pid is None else pid
+        record = {
+            "issue_number": ISSUE,
+            "branch_name": branch,
+            "remote": REMOTE,
+            "org": ORG,
+            "repo": REPO,
+            "worktree_path": worktree or self.worktree,
+            "session_pid": pid_value,
+            "pid": pid_value,
+            "lock_generation": generation,
+            "work_lease": lease,
+        }
+        path = self._path()
+        record["lock_file_path"] = path
+        issue_lock_store.save_lock_file(path, record)
+        return record
+
+
+class TestPolicyIsTheSingleSource(unittest.TestCase):
+    """AC-N7: one authoritative configuration source for every duration."""
+
+    def test_author_policy_carries_the_agreed_values(self):
+        policy = lease_policy.policy_for(lease_policy.TASK_CLASS_AUTHOR_ISSUE_WORK)
+        self.assertEqual(policy.initial_ttl_minutes, 10.0)
+        self.assertEqual(policy.heartbeat_cadence_minutes, 2.0)
+        self.assertEqual(policy.stale_warning_minutes, 5.0)
+        self.assertEqual(policy.missed_heartbeat_grace_minutes, 10.0)
+        self.assertEqual(policy.absolute_cap_hours, 8.0)
+        self.assertEqual(policy.recovery_grace_minutes, 10.0)
+        self.assertEqual(policy.terminal_race_drain_minutes, 2.0)
+        self.assertTrue(policy.terminal_retirement_eligible)
+        self.assertTrue(policy.heartbeat_lifecycle_active)
+
+    def test_the_four_hour_author_ttl_literal_is_gone(self):
+        """The duplicated literal AC-N7 exists to remove."""
+        self.assertFalse(hasattr(issue_lock_store, "WORK_LEASE_TTL_HOURS"))
+        import gitea_mcp_server
+
+        self.assertFalse(hasattr(gitea_mcp_server, "WORK_LEASE_TTL_HOURS"))
+
+    def test_declared_reviewer_values_match_the_module_still_using_them(self):
+        """Slice A declares reviewer/merger numbers without rewiring them.
+
+        Recording a value in two places is only safe if drift is detectable, so
+        this asserts the declaration still equals the constants #747 owns. When
+        Slice C migrates those call sites, this test becomes the proof the
+        migration changed nothing.
+        """
+        policy = lease_policy.policy_for(lease_policy.TASK_CLASS_REVIEWER_PR)
+        self.assertEqual(
+            policy.initial_ttl_minutes, float(reviewer_pr_lease.LEASE_TTL_MINUTES)
+        )
+        self.assertEqual(
+            policy.stale_warning_minutes,
+            float(reviewer_pr_lease.STALE_WARNING_MINUTES),
+        )
+        self.assertFalse(policy.heartbeat_lifecycle_active)
+
+    def test_declared_conflict_fix_value_matches_its_module(self):
+        policy = lease_policy.policy_for(lease_policy.TASK_CLASS_CONFLICT_FIX)
+        self.assertEqual(
+            policy.initial_ttl_minutes,
+            float(pr_work_lease.DEFAULT_CONFLICT_FIX_TTL_MINUTES),
+        )
+        self.assertFalse(policy.heartbeat_lifecycle_active)
+
+    def test_environment_override_applies(self):
+        var = lease_policy.env_var_name(
+            lease_policy.TASK_CLASS_AUTHOR_ISSUE_WORK, "initial_ttl_minutes"
+        )
+        with patch.dict(os.environ, {var: "7"}):
+            self.assertEqual(
+                lease_policy.policy_for(
+                    lease_policy.TASK_CLASS_AUTHOR_ISSUE_WORK
+                ).initial_ttl_minutes,
+                7.0,
+            )
+
+    def test_unusable_override_falls_back_instead_of_minting_a_zero_lease(self):
+        """A typo must not make every claim instantly reclaimable."""
+        var = lease_policy.env_var_name(
+            lease_policy.TASK_CLASS_AUTHOR_ISSUE_WORK, "initial_ttl_minutes"
+        )
+        for bad in ("0", "-5", "not-a-number", "   "):
+            with self.subTest(value=bad), patch.dict(os.environ, {var: bad}):
+                self.assertEqual(
+                    lease_policy.policy_for(
+                        lease_policy.TASK_CLASS_AUTHOR_ISSUE_WORK
+                    ).initial_ttl_minutes,
+                    10.0,
+                )
+
+    def test_unknown_task_class_does_not_raise(self):
+        policy = lease_policy.policy_for("something-new")
+        self.assertEqual(policy.task_class, lease_policy.TASK_CLASS_AUTHOR_ISSUE_WORK)
+
+
+class TestLifecycleDiscrimination(_LockFixture):
+    """AC-N8: the marker, never a timestamp, decides legacy vs heartbeat."""
+
+    def test_missing_marker_reads_as_legacy(self):
+        record = self.write_lock(lifecycle=None)
+        self.assertTrue(issue_lock_store.is_legacy_lease(record))
+        self.assertEqual(
+            issue_lock_store.lease_lifecycle_version(record),
+            lease_policy.LIFECYCLE_LEGACY,
+        )
+
+    def test_marker_present_reads_as_heartbeat_lifecycle(self):
+        record = self.write_lock()
+        self.assertFalse(issue_lock_store.is_legacy_lease(record))
+
+    def test_equal_created_and_heartbeat_never_implies_a_fresh_heartbeat(self):
+        """The exact inversion AC-N8 forbids.
+
+        A legacy lock has ``last_heartbeat_at == created_at`` forever because
+        nothing ever advanced it. Reading that equality as "recently
+        heartbeated" would classify every never-heartbeated lock as fresh.
+        """
+        legacy = self.write_lock(
+            lifecycle=None,
+            created_delta=timedelta(hours=3),
+            heartbeat_delta=timedelta(hours=3),
+        )
+        lease = legacy["work_lease"]
+        self.assertEqual(lease["created_at"], lease["last_heartbeat_at"])
+        self.assertTrue(issue_lock_store.is_legacy_lease(legacy))
+
+        # A brand-new heartbeat lease has them equal too, so the equality
+        # carries no information in either direction.
+        fresh = self.write_lock(
+            created_delta=timedelta(seconds=0), heartbeat_delta=timedelta(seconds=0)
+        )
+        self.assertEqual(
+            fresh["work_lease"]["created_at"],
+            fresh["work_lease"]["last_heartbeat_at"],
+        )
+        self.assertFalse(issue_lock_store.is_legacy_lease(fresh))
+
+    def test_minted_session_id_contains_no_pid(self):
+        """AC-N1: the ownership key must not be derived from the daemon pid."""
+        minted = issue_lock_store.mint_task_session_id()
+        self.assertNotIn(str(os.getpid()), minted)
+        self.assertNotEqual(minted, issue_lock_store.mint_task_session_id())
+
+
+class TestFreshnessIsHeartbeatDriven(_LockFixture):
+    """AC-N2 and the new bands."""
+
+    def test_fresh_heartbeat_is_live(self):
+        record = self.write_lock(heartbeat_delta=timedelta(minutes=1))
+        fresh = issue_lock_store.assess_lock_freshness(record, now=self.now)
+        self.assertEqual(fresh["status"], issue_lock_store.STATUS_LIVE)
+        self.assertTrue(fresh["live"])
+        self.assertFalse(fresh["heartbeat_warning"])
+
+    def test_heartbeat_past_warning_is_still_live_but_flagged(self):
+        record = self.write_lock(heartbeat_delta=timedelta(minutes=6))
+        fresh = issue_lock_store.assess_lock_freshness(record, now=self.now)
+        self.assertEqual(fresh["status"], issue_lock_store.STATUS_LIVE)
+        self.assertTrue(fresh["heartbeat_warning"])
+
+    def test_missed_heartbeat_past_grace_is_classified_explicitly(self):
+        record = self.write_lock(
+            heartbeat_delta=timedelta(minutes=11),
+            expires_delta=timedelta(minutes=30),
+        )
+        fresh = issue_lock_store.assess_lock_freshness(record, now=self.now)
+        self.assertEqual(
+            fresh["status"], issue_lock_store.STATUS_STALE_MISSED_HEARTBEAT
+        )
+        self.assertFalse(fresh["live"])
+        self.assertTrue(fresh["stale"])
+
+    def test_alive_pid_never_establishes_freshness(self):
+        """The defect in one assertion.
+
+        The recorded PID is this very process, so it is unambiguously alive —
+        and the lease is still not live, because the task stopped heartbeating.
+        """
+        record = self.write_lock(
+            pid=os.getpid(),
+            heartbeat_delta=timedelta(hours=4),
+            expires_delta=timedelta(hours=4),
+        )
+        fresh = issue_lock_store.assess_lock_freshness(record, now=self.now)
+        self.assertTrue(fresh["pid_alive"])
+        self.assertFalse(fresh["live"])
+        self.assertEqual(
+            fresh["status"], issue_lock_store.STATUS_STALE_MISSED_HEARTBEAT
+        )
+
+    def test_dead_pid_still_marks_stale_for_issue_753(self):
+        """The opposite asymmetry: dead-PID corroboration is preserved."""
+        record = self.write_lock(pid=DEAD_PID, heartbeat_delta=timedelta(minutes=1))
+        fresh = issue_lock_store.assess_lock_freshness(record, now=self.now)
+        self.assertEqual(fresh["status"], issue_lock_store.STATUS_STALE)
+        self.assertFalse(fresh["live"])
+        self.assertIn("not alive", fresh["reason"])
+
+    def test_absolute_cap_requires_readoption(self):
+        record = self.write_lock(
+            created_delta=timedelta(hours=9), heartbeat_delta=timedelta(minutes=1)
+        )
+        fresh = issue_lock_store.assess_lock_freshness(record, now=self.now)
+        self.assertEqual(fresh["status"], issue_lock_store.STATUS_STALE_ABSOLUTE_CAP)
+        self.assertIn("re-adoption", fresh["reason"])
+
+    def test_heartbeat_lifecycle_without_a_heartbeat_fails_closed(self):
+        record = self.write_lock()
+        del record["work_lease"]["last_heartbeat_at"]
+        issue_lock_store.save_lock_file(self._path(), record)
+        fresh = issue_lock_store.assess_lock_freshness(record, now=self.now)
+        self.assertEqual(
+            fresh["status"], issue_lock_store.STATUS_STALE_MISSED_HEARTBEAT
+        )
+        self.assertIn("fail closed", fresh["reason"])
+
+    def test_absent_lock(self):
+        fresh = issue_lock_store.assess_lock_freshness(None)
+        self.assertEqual(fresh["status"], issue_lock_store.STATUS_ABSENT)
+        self.assertFalse(fresh["stale"])
+
+
+class TestLegacyLocksStayProtected(_LockFixture):
+    """AC-N8: deployment must not retroactively shorten an existing claim."""
+
+    def test_legacy_lock_with_a_stale_heartbeat_remains_live(self):
+        """The deployment-safety case.
+
+        A four-hour legacy lease minted three hours ago has not heartbeated
+        once. Under the new grace it would be long gone; under its preserved
+        absolute expiry it is still live, and must stay that way.
+        """
+        record = self.write_lock(
+            lifecycle=None,
+            created_delta=timedelta(hours=3),
+            heartbeat_delta=timedelta(hours=3),
+            expires_delta=timedelta(hours=1),
+        )
+        fresh = issue_lock_store.assess_lock_freshness(record, now=self.now)
+        self.assertEqual(fresh["status"], issue_lock_store.STATUS_LIVE)
+        self.assertTrue(fresh["live"])
+        self.assertTrue(fresh["legacy_lease"])
+        self.assertTrue(fresh["legacy_expiry_preserved"])
+
+    def test_legacy_lock_past_its_absolute_expiry_is_expired_as_before(self):
+        record = self.write_lock(
+            lifecycle=None,
+            created_delta=timedelta(hours=5),
+            heartbeat_delta=timedelta(hours=5),
+            expires_delta=timedelta(hours=-1),
+        )
+        fresh = issue_lock_store.assess_lock_freshness(record, now=self.now)
+        self.assertEqual(fresh["status"], issue_lock_store.STATUS_EXPIRED)
+
+    def test_legacy_lock_is_never_reclaimed_by_the_heartbeat_band(self):
+        record = self.write_lock(
+            lifecycle=None,
+            created_delta=timedelta(hours=3),
+            heartbeat_delta=timedelta(hours=3),
+            expires_delta=timedelta(hours=1),
+        )
+        reclaim = issue_lock_store.assess_expired_lock_reclaim(record, now=self.now)
+        self.assertFalse(reclaim["reclaim_allowed"])
+
+
+class TestReclaimAfterMissedHeartbeat(_LockFixture):
+    def test_missed_heartbeat_makes_ownership_reclaimable(self):
+        record = self.write_lock(
+            pid=os.getpid(),
+            heartbeat_delta=timedelta(minutes=15),
+            expires_delta=timedelta(hours=3),
+        )
+        reclaim = issue_lock_store.assess_expired_lock_reclaim(record, now=self.now)
+        self.assertTrue(reclaim["reclaim_allowed"])
+        self.assertIn("stale_missed_heartbeat", reclaim["reasons"][0])
+
+    def test_live_lease_is_never_reclaimable(self):
+        record = self.write_lock(heartbeat_delta=timedelta(minutes=1))
+        reclaim = issue_lock_store.assess_expired_lock_reclaim(record, now=self.now)
+        self.assertFalse(reclaim["reclaim_allowed"])
+
+    def test_dead_pid_reclaim_path_is_unchanged(self):
+        """#753 must keep working through its original conditions."""
+        record = self.write_lock(pid=DEAD_PID, heartbeat_delta=timedelta(minutes=1))
+        reclaim = issue_lock_store.assess_expired_lock_reclaim(record, now=self.now)
+        self.assertTrue(reclaim["reclaim_allowed"])
+        self.assertTrue(reclaim["owner_pid_dead"])
+
+
+class TestHeartbeatWriter(_LockFixture):
+    """A4: flock + CAS + exact verification, and no revival path."""
+
+    def _heartbeat(self, **kwargs):
+        params = {
+            "remote": REMOTE,
+            "org": ORG,
+            "repo": REPO,
+            "issue_number": ISSUE,
+            "branch_name": BRANCH,
+            "worktree_path": self.worktree,
+            "identity": IDENTITY,
+            "profile": PROFILE,
+            "task_session_id": "author_issue_work-aaaabbbbccccdddd",
+            "lock_dir": self.lock_dir.name,
+            "now": self.now,
+        }
+        params.update(kwargs)
+        return issue_lock_store.heartbeat_session_lock(**params)
+
+    def test_heartbeat_slides_expiry_and_advances_generation(self):
+        self.write_lock(heartbeat_delta=timedelta(minutes=4), generation=5)
+        result = self._heartbeat()
+        self.assertTrue(result["success"], result)
+        self.assertEqual(result["prior_generation"], 5)
+        self.assertEqual(result["lock_generation"], 6)
+        self.assertEqual(result["heartbeat_count"], 1)
+        self.assertEqual(result["last_heartbeat_at"], _ts(self.now))
+        self.assertEqual(result["expires_at"], _ts(self.now + timedelta(minutes=10)))
+        self.assertTrue(result["freshness"]["live"])
+
+    def test_heartbeat_is_durable_and_repeatable(self):
+        self.write_lock(heartbeat_delta=timedelta(minutes=4))
+        self._heartbeat()
+        second = self._heartbeat(now=self.now + timedelta(minutes=1))
+        self.assertTrue(second["success"], second)
+        self.assertEqual(second["heartbeat_count"], 2)
+        written = issue_lock_store.read_lock_file(self._path())
+        self.assertEqual(written["work_lease"]["heartbeat_count"], 2)
+
+    def test_stale_generation_is_refused(self):
+        self.write_lock(generation=5)
+        result = self._heartbeat(expected_generation=4)
+        self.assertFalse(result["success"])
+        self.assertIn("generation changed", result["reasons"][0])
+
+    def test_foreign_session_is_refused(self):
+        self.write_lock()
+        result = self._heartbeat(task_session_id="author_issue_work-ffffffffffffffff")
+        self.assertFalse(result["success"])
+        self.assertIn("task_session_id does not match", " ".join(result["reasons"]))
+
+    def test_missing_session_id_is_refused(self):
+        self.write_lock()
+        result = self._heartbeat(task_session_id="")
+        self.assertFalse(result["success"])
+
+    def test_foreign_claimant_is_refused(self):
+        self.write_lock()
+        for field, value in (
+            ("identity", "someone-else"),
+            ("profile", "other-profile"),
+        ):
+            with self.subTest(field=field):
+                result = self._heartbeat(**{field: value})
+                self.assertFalse(result["success"])
+
+    def test_branch_and_worktree_mismatch_are_refused(self):
+        self.write_lock()
+        wrong_branch = self._heartbeat(branch_name=f"fix/issue-{ISSUE}-other")
+        self.assertFalse(wrong_branch["success"])
+        wrong_worktree = self._heartbeat(worktree_path="/tmp/not-the-worktree")
+        self.assertFalse(wrong_worktree["success"])
+
+    def test_lapsed_lease_cannot_be_heartbeated_back_to_life(self):
+        """No revival path (A4).
+
+        A session that stopped proving liveness must reclaim under a fresh
+        generation, not restore ownership retroactively.
+        """
+        self.write_lock(
+            heartbeat_delta=timedelta(minutes=30), expires_delta=timedelta(hours=1)
+        )
+        result = self._heartbeat()
+        self.assertFalse(result["success"])
+        self.assertIn("reclaimed", " ".join(result["reasons"]))
+
+    def test_absent_lock_cannot_be_created_by_heartbeat(self):
+        result = self._heartbeat()
+        self.assertFalse(result["success"])
+        self.assertIn("no durable lock", result["reasons"][0])
+
+    def test_legacy_lock_is_refused_until_rebound(self):
+        self.write_lock(lifecycle=None)
+        result = self._heartbeat()
+        self.assertFalse(result["success"])
+        self.assertTrue(result["legacy_lease"])
+        self.assertIn("rebound", " ".join(result["reasons"]))
+
+
+class TestLegacyRebind(_LockFixture):
+    """AC-N8 exit route: canonical exact-owner rebinding."""
+
+    def _rebind(self, **kwargs):
+        params = {
+            "remote": REMOTE,
+            "org": ORG,
+            "repo": REPO,
+            "issue_number": ISSUE,
+            "branch_name": BRANCH,
+            "worktree_path": self.worktree,
+            "identity": IDENTITY,
+            "profile": PROFILE,
+            "lock_dir": self.lock_dir.name,
+            "now": self.now,
+        }
+        params.update(kwargs)
+        return issue_lock_store.rebind_legacy_lock(**params)
+
+    def test_rebind_mints_a_session_and_a_genuine_first_heartbeat(self):
+        self.write_lock(
+            lifecycle=None,
+            created_delta=timedelta(hours=3),
+            heartbeat_delta=timedelta(hours=3),
+            expires_delta=timedelta(hours=1),
+            generation=2,
+        )
+        result = self._rebind()
+        self.assertTrue(result["success"], result)
+        self.assertTrue(result["task_session_id"])
+        self.assertEqual(result["lock_generation"], 3)
+
+        written = issue_lock_store.read_lock_file(self._path())
+        lease = written["work_lease"]
+        self.assertEqual(
+            lease["lifecycle_version"], lease_policy.LIFECYCLE_HEARTBEAT_V1
+        )
+        self.assertEqual(lease["last_heartbeat_at"], _ts(self.now))
+        self.assertEqual(lease["expires_at"], _ts(self.now + timedelta(minutes=10)))
+        self.assertFalse(issue_lock_store.is_legacy_lease(written))
+        # The original claim is preserved for audit rather than overwritten.
+        origin = written["legacy_rebind"]["legacy_origin"]
+        self.assertTrue(origin["created_at"])
+        self.assertEqual(origin["lifecycle"], lease_policy.LIFECYCLE_LEGACY)
+
+    def test_rebound_lock_can_then_heartbeat(self):
+        self.write_lock(
+            lifecycle=None,
+            created_delta=timedelta(hours=3),
+            heartbeat_delta=timedelta(hours=3),
+            expires_delta=timedelta(hours=1),
+        )
+        rebound = self._rebind()
+        beat = issue_lock_store.heartbeat_session_lock(
+            remote=REMOTE,
+            org=ORG,
+            repo=REPO,
+            issue_number=ISSUE,
+            branch_name=BRANCH,
+            worktree_path=self.worktree,
+            identity=IDENTITY,
+            profile=PROFILE,
+            task_session_id=rebound["task_session_id"],
+            lock_dir=self.lock_dir.name,
+            now=self.now + timedelta(minutes=1),
+        )
+        self.assertTrue(beat["success"], beat)
+
+    def test_rebind_refuses_a_foreign_owner(self):
+        self.write_lock(lifecycle=None, expires_delta=timedelta(hours=1))
+        result = self._rebind(identity="someone-else")
+        self.assertFalse(result["success"])
+
+    def test_rebind_refuses_a_lock_already_on_the_lifecycle(self):
+        self.write_lock()
+        result = self._rebind()
+        self.assertFalse(result["success"])
+        self.assertFalse(result["legacy_lease"])
+
+    def test_rebind_is_not_a_recovery_path_for_a_lapsed_legacy_lease(self):
+        """An expired legacy lease belongs to #760 renewal or #601 reclaim."""
+        self.write_lock(
+            lifecycle=None,
+            created_delta=timedelta(hours=5),
+            heartbeat_delta=timedelta(hours=5),
+            expires_delta=timedelta(hours=-1),
+        )
+        result = self._rebind()
+        self.assertFalse(result["success"])
+        self.assertIn("not a recovery path", " ".join(result["reasons"]))
+
+
+if __name__ == "__main__":
+    unittest.main()

tests/test_webui_shell.py

@@ -0,0 +1,135 @@
+"""Tests for the Phase 1 operator console application shell (#638)."""
+import sys
+import unittest
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
+
+from starlette.routing import Route
+from starlette.testclient import TestClient
+
+from webui import layout
+from webui.app import create_app
+from webui.nav import NAV_GROUPS, STUB_PAGES, nav_hrefs
+
+
+class TestShellNav(unittest.TestCase):
+    def setUp(self):
+        self.client = TestClient(create_app())
+
+    def test_nav_group_labels_present(self):
+        text = self.client.get("/").text
+        for group in NAV_GROUPS:
+            with self.subTest(group=group.label):
+                self.assertIn(f">{group.label}<", text)
+
+    def test_phase1_group_labels_cover_expected_ia(self):
+        labels = {group.label for group in NAV_GROUPS}
+        for expected in (
+            "Health",
+            "Traffic",
+            "Runtime/Sessions",
+            "Projects",
+            "Inventory",
+            "Timeline",
+            "Policy",
+            "Insights",
+        ):
+            with self.subTest(label=expected):
+                self.assertIn(expected, labels)
+
+    def test_every_nav_href_resolves_to_a_get_route(self):
+        app = create_app()
+        get_paths = {
+            route.path
+            for route in app.routes
+            if isinstance(route, Route) and "GET" in route.methods
+        }
+        for href in nav_hrefs():
+            with self.subTest(href=href):
+                self.assertIn(href, get_paths, f"nav href {href} has no GET route")
+
+    def test_legacy_hrefs_still_navigable(self):
+        text = self.client.get("/").text
+        for href in ("/queue", "/projects", "/prompts", "/runtime",
+                     "/audit", "/worktrees", "/leases", "/actions"):
+            with self.subTest(href=href):
+                self.assertIn(f'href="{href}"', text)
+
+
+class TestShellBadges(unittest.TestCase):
+    def setUp(self):
+        self.client = TestClient(create_app())
+
+    def test_mode_badge_present(self):
+        self.assertIn("mode: read-only", self.client.get("/").text)
+
+    def test_environment_badge_present(self):
+        self.assertIn("env:", self.client.get("/").text)
+
+    def test_default_environment_is_local(self):
+        self.assertEqual(layout.environment_label(), "local")
+
+    def test_remote_bind_reports_remote_environment(self):
+        import os
+
+        prior = os.environ.get("WEBUI_HOST")
+        os.environ["WEBUI_HOST"] = "10.0.0.5"
+        try:
+            self.assertEqual(layout.environment_label(), "remote")
+        finally:
+            if prior is None:
+                os.environ.pop("WEBUI_HOST", None)
+            else:
+                os.environ["WEBUI_HOST"] = prior
+
+    def test_docs_link_present(self):
+        text = self.client.get("/").text
+        self.assertIn(layout.DOCS_URL, text)
+        self.assertIn(">Docs<", text)
+
+
+class TestShellStubs(unittest.TestCase):
+    def setUp(self):
+        self.client = TestClient(create_app())
+
+    def test_stub_routes_render_200(self):
+        for path, (title, _desc) in STUB_PAGES.items():
+            with self.subTest(path=path):
+                response = self.client.get(path)
+                self.assertEqual(response.status_code, 200, path)
+                self.assertIn(title, response.text)
+                self.assertIn("placeholder", response.text)
+
+    def test_stub_routes_are_read_only(self):
+        for path in STUB_PAGES:
+            with self.subTest(path=path):
+                response = self.client.post(path)
+                self.assertEqual(response.status_code, 405)
+                self.assertEqual(response.json()["error"], "read-only-mvp")
+
+    def test_stub_pages_carry_nav_and_badges(self):
+        response = self.client.get("/inventory")
+        self.assertIn("mode: read-only", response.text)
+        self.assertIn('href="/queue"', response.text)
+
+
+class TestShellHome(unittest.TestCase):
+    def setUp(self):
+        self.client = TestClient(create_app())
+
+    def test_home_summarizes_console(self):
+        text = self.client.get("/").text
+        self.assertIn("Operator console", text)
+        self.assertIn("Phase 1", text)
+
+    def test_home_links_legacy_pages(self):
+        text = self.client.get("/").text
+        self.assertIn("MVP legacy pages", text)
+        for href in ("/queue", "/audit", "/leases"):
+            with self.subTest(href=href):
+                self.assertIn(f'href="{href}"', text)
+
+
+if __name__ == "__main__":
+    unittest.main()

webui/app.py

@@ -12,6 +12,7 @@ from starlette.routing import Route
 
 from webui.deployment_boundary import deployment_snapshot
 from webui.layout import render_page
+from webui.nav import NAV_GROUPS, STUB_PAGES
 from webui.project_registry import (
     ProjectRegistry,
     RegistryError,
@@ -45,6 +46,7 @@ from webui.worktree_scanner import load_hygiene_snapshot, snapshot_to_dict as wo
 from webui.worktree_views import render_worktrees_page
 from webui.runtime_health import load_runtime_snapshot, snapshot_to_dict as runtime_snapshot_to_dict
 from webui.runtime_views import render_runtime_page
+from webui.timeline import load_timeline, snapshot_to_dict as timeline_snapshot_to_dict
 from webui.system_health import (
     API_PATH as SYSTEM_HEALTH_API_PATH,
     load_system_health,
@@ -65,24 +67,62 @@ def _stub_page(title: str, description: str) -> HTMLResponse:
     return HTMLResponse(render_page(title=title, body_html=body))
 
 
+_LEGACY_PAGES = (
+    ("/queue", "Queue", "live PR and issue dashboard (#429)"),
+    ("/projects", "Projects", "registry and onboarding (#427)"),
+    ("/prompts", "Prompts", "canonical workflow prompt library (#428)"),
+    ("/runtime", "Runtime", "MCP health and stale-runtime detection (#430)"),
+    ("/audit", "Audit", "final-report paste and validator preview (#431)"),
+    ("/worktrees", "Worktrees", "branch hygiene dashboard (#432)"),
+    ("/leases", "Leases", "collision and lease visibility (#433)"),
+    ("/actions", "Actions", "gated write-action framework (#434)"),
+)
+
+
+def _render_home_nav_groups() -> str:
+    groups = []
+    for group in NAV_GROUPS:
+        items = "".join(
+            f'<li><a href="{item.href}">{item.label}</a>'
+            + ("" if item.status == "live" else " <span class=\"muted\">(stub)</span>")
+            + "</li>"
+            for item in group.items
+        )
+        groups.append(f"<h3>{group.label}</h3><ul>{items}</ul>")
+    return "".join(groups)
+
+
 async def home(_request: Request) -> HTMLResponse:
+    legacy = "".join(
+        f"<li><strong>{label}</strong> — {desc} "
+        f'(<a href="{href}">{href}</a>)</li>'
+        for href, label, desc in _LEGACY_PAGES
+    )
     body = (
         "<h2>Operator console</h2>"
-        "<p>Local entry point for MCP Control Plane operational views.</p>"
+        "<p>Read-only home for the MCP Control Plane Phase 1 operator console. "
-        "<ul>"
+        "Gitea, MCP capability gates, and canonical workflows remain the source "
-        "<li><strong>Queue</strong> — live PR and issue dashboard (#429)</li>"
+        "of truth; this console never mutates them.</p>"
-        "<li><strong>Projects</strong> — registry and onboarding (#427)</li>"
+        "<h2>Phase 1 surfaces</h2>"
-        "<li><strong>Prompts</strong> — canonical workflow prompt library (#428)</li>"
+        + _render_home_nav_groups()
-        "<li><strong>Runtime</strong> — MCP health and stale-runtime detection (#430)</li>"
+        + "<h2>MVP legacy pages</h2>"
-        "<li><strong>Audit</strong> — final-report paste and validator preview (#431)</li>"
+        "<ul>" + legacy + "</ul>"
-        "<li><strong>Worktrees</strong> — branch hygiene dashboard (#432)</li>"
-        "<li><strong>Leases</strong> — collision and lease visibility (#433)</li>"
-        "<li><strong>Actions</strong> — gated write-action framework (#434)</li>"
-        "</ul>"
     )
     return HTMLResponse(render_page(title="Home", body_html=body))
 
 
+async def phase_stub(request: Request) -> HTMLResponse:
+    """Graceful read-only placeholder for a not-yet-implemented Phase 1 surface."""
+    title, description = STUB_PAGES[request.url.path]
+    body = (
+        f"<h2>{title}</h2>"
+        f'<div class="stub"><p>{description}</p>'
+        "<p>Phase 1 shell placeholder — no write actions. Tracked under "
+        "epic #631.</p></div>"
+    )
+    return HTMLResponse(render_page(title=title, body_html=body))
+
+
 async def health(_request: Request) -> JSONResponse:
     """Liveness only — deliberately cheap, runs no dependency probe (#634).
 
@@ -410,6 +450,104 @@ async def api_console_security_model(_request: Request) -> JSONResponse:
     })
 
 
+def _query_int(request: Request, key: str) -> int | None:
+    """Parse an optional integer query parameter; None when absent/invalid."""
+    raw = request.query_params.get(key)
+    if raw is None or not str(raw).strip():
+        return None
+    try:
+        return int(str(raw).strip())
+    except (TypeError, ValueError):
+        return None
+
+
+def _derive_remote(host: str) -> str:
+    """Map a Gitea host to its known short remote name (control-plane scope key)."""
+    text = (host or "").lower()
+    if "prgs" in text:
+        return "prgs"
+    if "dadeschools" in text:
+        return "dadeschools"
+    return text.split(".")[0] if text else ""
+
+
+def _timeline_comment_source(host: str, org: str, repo: str):
+    """Build a fail-soft CTH-comment fetcher for one repo, or None when offline.
+
+    Returns a callable ``(kind, number) -> list[comment]``. Credentials or
+    network failures raise inside the callable so ``load_timeline`` degrades the
+    handoff source rather than the whole timeline. Offline test mode yields no
+    live source so the handoff section reports ``not run``.
+    """
+    import os
+
+    from gitea_auth import api_fetch_page, get_auth_header, repo_api_url
+
+    offline = (os.environ.get("WEBUI_TEST_OFFLINE") or "").strip().lower() in {"1", "true", "yes"}
+    if offline:
+        return None
+    auth = get_auth_header(host)
+    if not auth:
+        return None
+
+    def _fetch(kind: str, number: int) -> list:
+        segment = "pulls" if kind == "pr" else "issues"
+        url = f"{repo_api_url(host, org, repo)}/{segment}/{int(number)}/comments"
+        comments: list = []
+        page = 1
+        while page <= 20:
+            raw, meta = api_fetch_page(url, auth, page=page, limit=50)
+            comments.extend(raw)
+            if bool(meta["is_final_page"]):
+                break
+            page += 1
+        return comments
+
+    return _fetch
+
+
+async def api_v1_timeline(request: Request) -> JSONResponse:
+    """Read-only workflow-event timeline (#637). Filter by issue/PR/session."""
+    from webui.queue_loader import _host_from_url  # host normalisation helper
+
+    registry, error = _load_project_registry()
+    if error is not None:
+        return JSONResponse(error.to_dict(), status_code=500)
+    project = registry.projects[0] if registry.projects else None
+
+    org = request.query_params.get("org") or (project.gitea_owner if project else "")
+    repo = request.query_params.get("repo") or (project.repo_name if project else "")
+    host = _host_from_url(project.remote_host) if project else ""
+    remote = request.query_params.get("remote") or _derive_remote(host)
+
+    if not (remote and org and repo):
+        return JSONResponse(
+            {
+                "error": "timeline_scope_unresolved",
+                "detail": "no project in registry and no remote/org/repo query params provided",
+            },
+            status_code=400,
+        )
+
+    comment_source = _timeline_comment_source(host, org, repo) if (host and org and repo) else None
+
+    snapshot = load_timeline(
+        remote=remote,
+        org=org,
+        repo=repo,
+        issue=_query_int(request, "issue"),
+        pr=_query_int(request, "pr"),
+        session=(request.query_params.get("session") or None),
+        limit=_query_int(request, "limit"),
+        offset=_query_int(request, "offset"),
+        comment_source=comment_source,
+    )
+    # A filter no surviving source can carry is refused, not answered empty:
+    # a 200 with zero events would tell the operator no such activity exists.
+    status_code = 200 if snapshot.ok else 422
+    return JSONResponse(timeline_snapshot_to_dict(snapshot), status_code=status_code)
+
+
 async def method_not_allowed(request: Request, _exc: Exception) -> Response:
     path = request.url.path
     if path in _AUDIT_MUTATION_PATHS and request.method == "POST":
@@ -449,6 +587,7 @@ def create_app(*, bind_host: str | None = None) -> Starlette:
             Route("/api/prompts", api_prompts, methods=["GET"]),
             Route("/runtime", runtime, methods=["GET"]),
             Route("/api/runtime", api_runtime, methods=["GET"]),
+            Route("/api/v1/timeline", api_v1_timeline, methods=["GET"]),
             Route("/audit", audit, methods=["GET", "POST"]),
             Route("/api/audit", api_audit, methods=["GET", "POST"]),
             Route("/worktrees", worktrees, methods=["GET"]),
@@ -472,6 +611,10 @@ def create_app(*, bind_host: str | None = None) -> Starlette:
                 api_console_security_model,
                 methods=["GET"],
             ),
+            *[
+                Route(path, phase_stub, methods=["GET"])
+                for path in STUB_PAGES
+            ],
         ],
         exception_handlers={405: method_not_allowed},
     )

webui/layout.py

@@ -2,28 +2,66 @@
 
 from __future__ import annotations
 
-NAV_ITEMS = (
+import os
-    ("/", "Home"),
+
-    ("/queue", "Queue"),
+from webui.nav import NAV_GROUPS
-    ("/projects", "Projects"),
-    ("/prompts", "Prompts"),
-    ("/runtime", "Runtime"),
-    ("/audit", "Audit"),
-    ("/worktrees", "Worktrees"),
-    ("/leases", "Leases"),
-    ("/actions", "Actions"),
-)
 
 MVP_NOTICE = (
     "Read-only MVP — Gitea, MCP tools, and canonical workflows remain the "
     "source of truth. No mutation endpoints."
 )
 
+# Canonical docs entry point surfaced from the shell header (#638).
+DOCS_URL = (
+    "https://gitea.prgs.cc/Scaled-Tech-Consulting/Gitea-Tools/src/branch/"
+    "master/docs/webui-local-dev.md"
+)
+
+_LOCAL_HOSTS = frozenset({"", "127.0.0.1", "localhost", "::1"})
+
+
+def environment_label() -> str:
+    """Classify the serving environment as ``local`` or ``remote`` (#638).
+
+    Derived from the same ``WEBUI_HOST`` default the app binds to; loopback
+    hosts are ``local``, anything else is ``remote``. Read-only signal only.
+    """
+    host = (os.environ.get("WEBUI_HOST", "127.0.0.1") or "").strip().lower()
+    return "local" if host in _LOCAL_HOSTS else "remote"
+
+
+def _render_nav() -> str:
+    groups_html = []
+    for group in NAV_GROUPS:
+        links = "".join(
+            f'<a href="{item.href}"'
+            + (' class="nav-stub"' if item.status == "stub" else "")
+            + f'>{item.label}</a>'
+            for item in group.items
+        )
+        groups_html.append(
+            '<div class="nav-group">'
+            f'<span class="nav-group-label">{group.label}</span>'
+            f'<span class="nav-group-links">{links}</span>'
+            "</div>"
+        )
+    return "".join(groups_html)
+
+
+def _render_badges() -> str:
+    env = environment_label()
+    return (
+        '<div class="header-badges">'
+        f'<span class="badge env-badge env-{env}">env: {env}</span>'
+        '<span class="badge mode-badge">mode: read-only</span>'
+        f'<a class="badge docs-link" href="{DOCS_URL}">Docs</a>'
+        "</div>"
+    )
+
 
 def render_page(*, title: str, body_html: str, extra_head: str = "") -> str:
-    nav_links = "".join(
+    nav_links = _render_nav()
-        f'<a href="{href}">{label}</a>' for href, label in NAV_ITEMS
+    header_badges = _render_badges()
-    )
     return f"""<!DOCTYPE html>
 <html lang="en">
 <head>
@@ -53,21 +91,58 @@ def render_page(*, title: str, body_html: str, extra_head: str = "") -> str:
       padding: 0.75rem 1.25rem;
     }}
     header h1 {{
-      margin: 0 0 0.5rem;
+      margin: 0;
       font-size: 1.1rem;
       font-weight: 600;
     }}
+    .header-top {{
+      display: flex;
+      flex-wrap: wrap;
+      align-items: center;
+      justify-content: space-between;
+      gap: 0.5rem 1rem;
+      margin-bottom: 0.6rem;
+    }}
+    .header-badges {{ display: inline-flex; flex-wrap: wrap; gap: 0.4rem; }}
+    .env-badge.env-local {{ color: #8fd19e; border-color: #3d6b4a; }}
+    .env-badge.env-remote {{ color: #e0c27a; border-color: #6b5730; }}
+    .mode-badge {{ color: #9ec8f0; border-color: #3d5f7a; }}
+    a.docs-link {{
+      color: var(--accent);
+      border-color: var(--accent);
+      text-decoration: none;
+      text-transform: none;
+    }}
+    a.docs-link:hover {{ filter: brightness(1.12); }}
     nav {{
       display: flex;
       flex-wrap: wrap;
-      gap: 0.75rem 1rem;
+      gap: 0.5rem 1.25rem;
     }}
+    .nav-group {{
+      display: flex;
+      flex-direction: column;
+      gap: 0.15rem;
+    }}
+    .nav-group-label {{
+      font-size: 0.68rem;
+      text-transform: uppercase;
+      letter-spacing: 0.04em;
+      color: var(--muted);
+    }}
+    .nav-group-links {{ display: inline-flex; flex-wrap: wrap; gap: 0.6rem; }}
     nav a {{
       color: var(--accent);
       text-decoration: none;
       font-size: 0.9rem;
     }}
     nav a:hover {{ text-decoration: underline; }}
+    nav a.nav-stub {{ color: var(--muted); }}
+    nav a.nav-stub::after {{
+      content: " ·stub";
+      font-size: 0.7rem;
+      color: var(--muted);
+    }}
     main {{
       max-width: 52rem;
       margin: 0 auto;
@@ -166,7 +241,10 @@ def render_page(*, title: str, body_html: str, extra_head: str = "") -> str:
 </head>
 <body>
   <header>
-    <h1>MCP Control Plane</h1>
+    <div class="header-top">
+      <h1>MCP Control Plane</h1>
+      {header_badges}
+    </div>
     <nav>{nav_links}</nav>
   </header>
   <main>

webui/nav.py

@@ -0,0 +1,111 @@
+"""Navigation IA for the Phase 1 operator console shell (#638).
+
+Single source of truth for the console navigation so ``webui/layout.py`` and
+the ``webui/app.py`` route table stay aligned with epic #631. Read-only: every
+destination is a GET view or a Phase 1 placeholder. No mutation links.
+
+Nav groups follow the #631 Phase 1 information architecture: Health, Traffic,
+Runtime/Sessions, Projects, Inventory, Timeline, Policy (placeholder), and
+Insights (placeholder). Later-phase surfaces are declared as ``stub`` items and
+backed by ``STUB_PAGES`` so their nav links resolve to a graceful placeholder
+instead of a 404.
+"""
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+
+@dataclass(frozen=True)
+class NavItem:
+    """A single navigation destination.
+
+    ``status`` is ``"live"`` for implemented views and ``"stub"`` for Phase 1
+    placeholders whose backing view lands in a later child issue.
+    """
+
+    href: str
+    label: str
+    status: str = "live"
+
+
+@dataclass(frozen=True)
+class NavGroup:
+    label: str
+    items: tuple[NavItem, ...]
+
+
+NAV_GROUPS: tuple[NavGroup, ...] = (
+    NavGroup("Health", (
+        NavItem("/health", "Liveness"),
+    )),
+    NavGroup("Traffic", (
+        NavItem("/queue", "Queue"),
+        NavItem("/leases", "Leases"),
+        NavItem("/actions", "Actions"),
+    )),
+    NavGroup("Runtime/Sessions", (
+        NavItem("/runtime", "Runtime health"),
+        NavItem("/sessions", "Sessions", "stub"),
+    )),
+    NavGroup("Projects", (
+        NavItem("/projects", "Projects"),
+    )),
+    NavGroup("Inventory", (
+        NavItem("/inventory", "Inventory", "stub"),
+        NavItem("/worktrees", "Worktrees"),
+    )),
+    NavGroup("Timeline", (
+        NavItem("/timeline", "Timeline", "stub"),
+    )),
+    NavGroup("Policy", (
+        NavItem("/policy", "Policy", "stub"),
+        NavItem("/prompts", "Prompts"),
+    )),
+    NavGroup("Insights", (
+        NavItem("/insights", "Insights", "stub"),
+        NavItem("/audit", "Audit"),
+    )),
+)
+
+
+# Phase 1 placeholder destinations whose backing views land in later child
+# issues of epic #631. Each maps a path to (title, description). Routes are
+# registered so nav links resolve to a graceful, read-only stub page.
+STUB_PAGES: dict[str, tuple[str, str]] = {
+    "/sessions": (
+        "Sessions",
+        "Active session, capability, and role inventory. Backed by the unified "
+        "inventory API (#636) once it lands.",
+    ),
+    "/inventory": (
+        "Inventory",
+        "Unified sessions, leases, locks, namespaces, and worktree inventory. "
+        "Backed by the Phase 1 inventory API (#636).",
+    ),
+    "/timeline": (
+        "Timeline",
+        "Workflow event timeline across issues and PRs. A later Phase 1 surface.",
+    ),
+    "/policy": (
+        "Policy",
+        "Capability and role policy surface. Placeholder until a later phase.",
+    ),
+    "/insights": (
+        "Insights",
+        "Aggregate operational insights and trends. Placeholder until a later "
+        "phase.",
+    ),
+}
+
+
+def iter_nav_items():
+    """Yield every ``NavItem`` across all groups in declared order."""
+    for group in NAV_GROUPS:
+        for item in group.items:
+            yield item
+
+
+def nav_hrefs() -> tuple[str, ...]:
+    """Return every navigation href in declared order."""
+    return tuple(item.href for item in iter_nav_items())

webui/timeline.py

@@ -0,0 +1,906 @@
+"""Workflow-event and conversation timeline model (#637, Phase 1).
+
+Operators cannot browse a unified timeline of workflow events, decisions,
+tool calls, and handoffs: the evidence is scattered across control-plane
+events, Gitea canonical handoff comments, and local logs. This module defines
+one durable, versioned event schema and per-source adapters that normalise
+those scattered records into a single ``WorkflowEvent`` stream, plus a
+read-only query layer (filter by issue / PR / session, stable ordering,
+pagination) that the ``/api/v1/timeline`` route serves.
+
+Design rules honoured here:
+
+- **Read-only.** Sources are read; nothing is mutated. The control-plane
+  database is opened through a ``mode=ro`` URI so a missing or unwritable DB
+  degrades to a reason instead of creating directories or running migrations.
+- **Fail-soft per source.** An unavailable source degrades to a status with a
+  reason rather than raising, and a source that could not run is never
+  rendered as an empty-and-healthy timeline.
+- **Answerable filters only.** Each source declares which filter dimensions it
+  can actually answer. A filter dimension no source that ran can carry is
+  refused with an explicit reason rather than silently matching nothing: an
+  empty page from an unanswerable filter reads to an operator as "no such
+  activity", which is a different — and false — statement.
+- **Redaction at the boundary, fail closed.** Every free-text field (event
+  messages, redacted tool arguments, decision/proof text) is run through the
+  console redaction policy before it leaves this module, and *before* any
+  structured value is derived from it — evidence references are extracted from
+  redacted text, then independently revalidated before serialization. An
+  unredactable value becomes the placeholder, and a value that cannot be proven
+  safe is dropped — an unredacted payload is never emitted, and a generation
+  error never drops raw data to a caller or a log.
+- **Stable ordering.** Events sort by ``(timestamp, source_rank, event_key)``
+  with a deterministic tiebreak, so pagination is stable across calls and
+  events with equal or missing timestamps keep a fixed order.
+
+Non-goals (from the issue): no full chat replay, no mutation of historical
+events, no unredacted tool-argument storage.
+"""
+
+from __future__ import annotations
+
+import re
+import sqlite3
+from dataclasses import dataclass, replace
+from datetime import datetime, timezone
+from typing import Any, Callable, Iterable
+
+import control_plane_db
+from webui import console_redaction
+
+# The schema is versioned so consumers can branch on shape. Bump on any
+# breaking change to WorkflowEvent's serialized form.
+TIMELINE_SCHEMA_VERSION = 1
+
+# Known event sources and their deterministic ordering rank. When two events
+# carry the same timestamp, the source rank breaks the tie before the
+# per-source event key, so a control-plane event and a handoff comment minted
+# in the same second always sort in a fixed order.
+SOURCE_CONTROL_PLANE = "control_plane"
+SOURCE_GITEA_HANDOFF = "gitea_handoff"
+_SOURCE_RANK = {
+    SOURCE_CONTROL_PLANE: 0,
+    SOURCE_GITEA_HANDOFF: 1,
+}
+
+# The filter dimensions the query layer accepts.
+FILTER_ISSUE = "issue"
+FILTER_PR = "pr"
+FILTER_SESSION = "session"
+
+# Which dimensions each source can actually answer. This is a property of the
+# underlying records, not of the query code: the control-plane ``events`` table
+# is (event_id, work_item_id, event_type, message, created_at) and carries no
+# session identity at all, so no control-plane event can ever match a session
+# filter. A CTH handoff comment can declare its session as a field, so the
+# handoff source answers all three. Filtering on a dimension the surviving
+# sources cannot carry is refused in ``load_timeline`` rather than answered
+# with an empty page.
+_SOURCE_FILTER_SUPPORT: dict[str, tuple[str, ...]] = {
+    SOURCE_CONTROL_PLANE: (FILTER_ISSUE, FILTER_PR),
+    SOURCE_GITEA_HANDOFF: (FILTER_ISSUE, FILTER_PR, FILTER_SESSION),
+}
+
+# Why a source cannot answer a dimension, for the refusal reason an operator reads.
+_SOURCE_FILTER_LIMITS: dict[tuple[str, str], str] = {
+    (SOURCE_CONTROL_PLANE, FILTER_SESSION): (
+        "control-plane events carry no session identity "
+        "(the events table has no session column)"
+    ),
+}
+
+# A timestamp far in the future so events with no parseable timestamp sort
+# last (after everything real) instead of first, without raising.
+_MISSING_TS_SORT = "9999-12-31T23:59:59Z"
+
+
+def _parse_ts(value: str | None) -> str | None:
+    """Normalise a timestamp to ``...Z`` UTC, or None when unparseable."""
+    if not value:
+        return None
+    text = str(value).strip()
+    if not text:
+        return None
+    candidate = text[:-1] + "+00:00" if text.endswith("Z") else text
+    try:
+        parsed = datetime.fromisoformat(candidate)
+    except ValueError:
+        return None
+    if parsed.tzinfo is None:
+        parsed = parsed.replace(tzinfo=timezone.utc)
+    return parsed.astimezone(timezone.utc).replace(microsecond=0).isoformat().replace("+00:00", "Z")
+
+
+def _redact(value: Any) -> Any:
+    """Redact a single free-text field, failing closed to the placeholder."""
+    if value is None:
+        return None
+    return console_redaction.redact_text(str(value))
+
+
+@dataclass(frozen=True)
+class WorkflowEvent:
+    """One normalised timeline event.
+
+    Every field is optional except ``source``/``event_type``/``event_key``
+    because sources carry different subsets. The class is frozen so an adapted
+    event is an immutable record; a consumer that needs a variant builds a new
+    one rather than mutating history.
+    """
+
+    source: str
+    event_type: str
+    event_key: str
+    timestamp: str | None = None
+    actor: str | None = None
+    role: str | None = None
+    issue_number: int | None = None
+    pr_number: int | None = None
+    session_id: str | None = None
+    tool_name: str | None = None
+    decision: str | None = None
+    message: str | None = None
+    correlation_id: str | None = None
+    evidence_refs: tuple[str, ...] = ()
+    sensitive: bool = False
+
+    def sort_key(self) -> tuple[str, int, str]:
+        return (
+            self.timestamp or _MISSING_TS_SORT,
+            _SOURCE_RANK.get(self.source, 99),
+            self.event_key,
+        )
+
+    def to_dict(self) -> dict[str, Any]:
+        return {
+            "source": self.source,
+            "event_type": self.event_type,
+            "event_key": self.event_key,
+            "timestamp": self.timestamp,
+            "actor": self.actor,
+            "role": self.role,
+            "issue_number": self.issue_number,
+            "pr_number": self.pr_number,
+            "session_id": self.session_id,
+            "tool_name": self.tool_name,
+            "decision": self.decision,
+            "message": self.message,
+            "correlation_id": self.correlation_id,
+            "evidence_refs": list(self.evidence_refs),
+            "sensitive": self.sensitive,
+        }
+
+
+# --------------------------------------------------------------------------- #
+# Adapters — pure functions from a source's raw records to WorkflowEvents.     #
+# Each is total: a malformed record is skipped, never raised on.               #
+# --------------------------------------------------------------------------- #
+
+# Event types whose payload is treated as sensitive and always redaction-hard
+# (they can carry lease/session provenance or tool arguments).
+_SENSITIVE_EVENT_HINTS = ("lease", "capability", "token", "auth", "secret")
+
+# Reference tokens (issue/PR/comment ids) and SHAs parsed out of proof text.
+_EVIDENCE_REF_RE = re.compile(r"(?:#|PR\s*#?|issue\s*#?|comment\s*#?)(\d+)", re.IGNORECASE)
+
+# A commit reference is only recognised when the text *declares* it as one.
+# A bare lowercase hex run is not evidence of anything: at 40 characters it is
+# exactly the shape of a Gitea personal access token, and at 7 it also matches
+# ordinary words such as "defaced". Requiring an anchoring keyword keeps real
+# references ("commit abc1234", "at head a209756...", "base caaae9b6") usable
+# while refusing to lift an undeclared secret-shaped run out of free text.
+_SHA_RE = re.compile(
+    r"(?i:\b(?:commit|sha|head|base|parent|revision|rev|merge[- ]base)\b[\s:=@#]*)"
+    r"([0-9a-f]{7,40})\b"
+)
+
+# Shapes a serialized evidence reference is allowed to take. Anything else is
+# dropped rather than emitted.
+_REF_ISSUE_SHAPE = re.compile(r"^#[0-9]{1,9}$")
+_REF_SHA_SHAPE = re.compile(r"^[0-9a-f]{7,40}$")
+
+# A long undelimited hex run with no declaring context is treated as credential
+# material wherever it appears, never as an identifier.
+_BARE_SECRET_SHAPE = re.compile(r"^[0-9a-f]{32,}$")
+
+# An event type reads like an identifier, but a stored one is externally
+# influenced: any producer that writes the control-plane ``events`` table
+# chooses the string. It reaches ``to_dict`` verbatim, so it is validated here
+# rather than trusted because of where it came from.
+_CP_EVENT_TYPE_SHAPE = re.compile(r"^[A-Za-z][A-Za-z0-9._:+-]{0,63}$")
+
+# Emitted in place of a value that cannot be proven safe. Deliberately not a
+# plausible workflow type: an unsafe value is refused, never quietly rewritten
+# into a different valid-looking one that would misdescribe the record.
+UNSAFE_EVENT_TYPE = "unsafe:redacted"
+
+# Emitted for a CTH heading that is not a declared member of ``CTH_TYPES``. The
+# contract is enforced on write (``format_cth_body``) and on assess; the read
+# path the timeline uses enforces it too rather than assuming it was.
+UNKNOWN_HANDOFF_EVENT_TYPE = "handoff:unrecognized"
+
+# A source record id is a plain integer in both sources it comes from: the
+# control-plane ``events`` primary key and a Gitea comment id. ``event_key`` is
+# serialized verbatim and is the pagination tiebreak, so anything else is
+# refused rather than interpolated into it.
+_RECORD_ID_SHAPE = re.compile(r"^[0-9]{1,19}$")
+
+
+def _kind_to_numbers(kind: str | None, number: int | None) -> tuple[int | None, int | None]:
+    """Map a control-plane work-item (kind, number) to (issue_no, pr_no)."""
+    if number is None:
+        return (None, None)
+    if kind == "pr":
+        return (None, int(number))
+    if kind == "issue":
+        return (int(number), None)
+    return (None, None)
+
+
+def _correlation_for(kind: str | None, number: int | None) -> str | None:
+    if number is None or kind not in ("issue", "pr"):
+        return None
+    return f"{kind}#{number}"
+
+
+def _extract_evidence_refs(*texts: str | None) -> tuple[str, ...]:
+    """Extract issue/PR and declared-commit references from **redacted** text.
+
+    Callers must pass text that has already been through :func:`_redact`; this
+    function derives a structured field from its input, so extracting ahead of
+    redaction would republish whatever redaction was about to remove. Every
+    reference is revalidated by :func:`_validated_evidence_refs` before it is
+    serialized.
+    """
+    refs: list[str] = []
+    for text in texts:
+        if not text:
+            continue
+        for match in _EVIDENCE_REF_RE.finditer(text):
+            token = f"#{match.group(1)}"
+            if token not in refs:
+                refs.append(token)
+        for match in _SHA_RE.finditer(text):
+            token = match.group(1)
+            if token not in refs:
+                refs.append(token)
+    return tuple(refs)
+
+
+def _validated_evidence_refs(refs: Iterable[str]) -> tuple[tuple[str, ...], bool]:
+    """Independently revalidate references immediately before serialization.
+
+    Extraction is not trusted on its own. A reference survives only when it has
+    a known reference shape and is unchanged by a second redaction pass — a
+    value the redaction policy would alter is credential material that must not
+    be emitted as a structured field. A full 40-character SHA stays usable
+    because extraction only accepts a hex run the source text explicitly
+    declared as a commit. Returns ``(safe_refs, dropped_any)``; ``dropped_any``
+    marks the event sensitive so the drop is visible rather than silent.
+    """
+    safe: list[str] = []
+    dropped = False
+    for ref in refs or ():
+        try:
+            token = str(ref).strip()
+            if not token:
+                continue
+            recognised = bool(_REF_ISSUE_SHAPE.match(token) or _REF_SHA_SHAPE.match(token))
+            if not recognised:
+                dropped = True
+                continue
+            if _redact(token) != token:
+                dropped = True
+                continue
+            if token not in safe:
+                safe.append(token)
+        except Exception:
+            # Fail closed: a reference that cannot be proven safe is dropped.
+            dropped = True
+            continue
+    return (tuple(safe), dropped)
+
+
+def _safe_session_id(value: Any) -> str | None:
+    """Return a session identifier only when it is safe to emit.
+
+    The value is authoritative source data — a session the record names for
+    itself — but it is still free text. It is dropped when redaction alters it
+    or when it is a bare secret-shaped hex run, so a credential parked in a
+    session field can never reach the payload or be echoed back by a filter.
+    """
+    if value is None:
+        return None
+    text = str(value).strip()
+    if not text:
+        return None
+    if _BARE_SECRET_SHAPE.match(text):
+        return None
+    return text if _redact(text) == text else None
+
+
+def _safe_record_id(value: Any) -> str | None:
+    """Return a source record id only when it is a plain numeric identifier.
+
+    ``event_key`` is serialized verbatim and is the deterministic pagination
+    tiebreak, so an id is interpolated into it only when it has the shape both
+    real sources actually produce. A record whose identity cannot be trusted is
+    refused by the caller rather than keyed on.
+    """
+    if value is None or isinstance(value, bool):
+        return None
+    if isinstance(value, int):
+        return str(value)
+    text = str(value).strip()
+    return text if _RECORD_ID_SHAPE.match(text) else None
+
+
+def _safe_cp_event_type(value: Any) -> tuple[str, bool]:
+    """Validate a stored control-plane event type. Returns ``(type, unsafe)``.
+
+    The stored value is externally influenced — whichever producer wrote the
+    ``events`` row chose the string — and ``to_dict`` serializes it verbatim, so
+    it passes a boundary of its own instead of relying on the one ``message``
+    passes. A value survives only when it is an ordinary identifier, is not a
+    bare secret-shaped hex run, and is unchanged by a redaction pass. Anything
+    else fails closed to :data:`UNSAFE_EVENT_TYPE`: the record stays visible as
+    an audit entry, but the value itself is never republished — not verbatim,
+    not partially sanitized, and not rewritten into some other valid-looking
+    type that would misdescribe what happened.
+    """
+    text = ("" if value is None else str(value)).strip()
+    if not text:
+        return ("", False)
+    if _BARE_SECRET_SHAPE.match(text):
+        return (UNSAFE_EVENT_TYPE, True)
+    if not _CP_EVENT_TYPE_SHAPE.match(text):
+        return (UNSAFE_EVENT_TYPE, True)
+    if _redact(text) != text:
+        return (UNSAFE_EVENT_TYPE, True)
+    return (text, False)
+
+
+def _safe_echo(value: Any) -> Any:
+    """Guard a scalar that is echoed back rather than derived from a record.
+
+    Query scope and filter values are caller-supplied and are reflected in the
+    response so an operator can see what was asked. Reflection is still
+    emission: a value redaction would alter, or a bare secret-shaped hex run, is
+    replaced by the placeholder instead of being echoed verbatim. Ordinary
+    scope and filter values pass through untouched.
+    """
+    if value is None or isinstance(value, (int, bool)):
+        return value
+    text = str(value)
+    if _BARE_SECRET_SHAPE.match(text.strip()):
+        return console_redaction.REDACTED
+    return _redact(text)
+
+
+def adapt_cp_events(rows: Iterable[dict[str, Any]]) -> list[WorkflowEvent]:
+    """Adapt control-plane ``events`` rows (joined to work_items) into events.
+
+    Each row is expected to carry ``event_id``, ``event_type``, ``message``,
+    ``created_at`` and the joined work-item ``kind``/``number``. Rows missing
+    an id or type are skipped so a partially written table never raises.
+    """
+    events: list[WorkflowEvent] = []
+    for row in rows or []:
+        try:
+            event_id = _safe_record_id(row.get("event_id"))
+            raw_event_type = (row.get("event_type") or "").strip()
+            if event_id is None or not raw_event_type:
+                continue
+            # The stored type is source data, not a trusted constant: validate
+            # it before it is serialized, exactly as `message` below is redacted
+            # before it is serialized.
+            event_type, event_type_unsafe = _safe_cp_event_type(raw_event_type)
+            kind = row.get("kind")
+            number = row.get("number")
+            issue_no, pr_no = _kind_to_numbers(kind, number)
+            sensitive = event_type_unsafe or any(
+                hint in raw_event_type.lower() for hint in _SENSITIVE_EVENT_HINTS
+            )
+            events.append(
+                WorkflowEvent(
+                    source=SOURCE_CONTROL_PLANE,
+                    event_type=event_type,
+                    event_key=f"cp:{event_id}",
+                    timestamp=_parse_ts(row.get("created_at")),
+                    issue_number=issue_no,
+                    pr_number=pr_no,
+                    # No session_id: the control-plane events table is
+                    # (event_id, work_item_id, event_type, message, created_at)
+                    # and records no session. Inventing one from the work item
+                    # or the message text would be a guess, so this source
+                    # declares the session dimension unsupported instead
+                    # (_SOURCE_FILTER_SUPPORT) and the query layer refuses a
+                    # session filter it cannot honestly answer.
+                    message=_redact(row.get("message")),
+                    correlation_id=_correlation_for(kind, number),
+                    sensitive=sensitive,
+                )
+            )
+        except Exception:
+            # A single malformed row must not sink the whole adaptation.
+            continue
+    return events
+
+
+def adapt_cth_comments(
+    comments: Iterable[dict[str, Any]],
+    *,
+    kind: str,
+    number: int,
+) -> list[WorkflowEvent]:
+    """Adapt Gitea Canonical Thread Handoff (CTH) comments into events.
+
+    Only comments that parse as a CTH (``canonical_thread_handoff.parse_cth_comment``)
+    become events; ordinary comments are ignored. ``kind``/``number`` scope the
+    events to the issue or PR the comments belong to.
+    """
+    # Imported lazily so this module has no import-time dependency on the
+    # handoff parser when only the control-plane adapter is used.
+    from canonical_thread_handoff import is_known_cth_type, parse_cth_comment
+
+    # ``kind``/``number`` are interpolated into event_key and correlation_id, so
+    # they are normalised once here. A scope this adapter cannot express is
+    # refused outright rather than serialized into an identifier.
+    kind = (kind or "").strip().lower()
+    if kind not in ("issue", "pr"):
+        return []
+    try:
+        number = int(number)
+    except (TypeError, ValueError):
+        return []
+
+    issue_no, pr_no = _kind_to_numbers(kind, number)
+    correlation = _correlation_for(kind, number)
+    events: list[WorkflowEvent] = []
+    for comment in comments or []:
+        try:
+            body = comment.get("body") or ""
+            parsed = parse_cth_comment(body)
+            if not parsed:
+                continue
+            fields = parsed.get("fields") or {}
+            cth_type = parsed.get("cth_type") or ""
+            comment_id = _safe_record_id(comment.get("id"))
+            if comment_id is None:
+                continue
+            # The CTH heading is free text: the parser accepts whatever follows
+            # "## CTH:", and only the write and assess paths check it against
+            # the contract. Check it here too — an unrecognised heading is
+            # reported as such rather than serialized into event_type, so
+            # arbitrary, malformed, or secret-shaped heading content has no way
+            # through. Declared types are preserved exactly.
+            cth_type_known = is_known_cth_type(cth_type)
+            # Redaction runs first, and every derived value is taken from the
+            # redacted text — deriving evidence refs from the raw proof would
+            # re-emit exactly what redaction was about to remove.
+            decision = _redact(fields.get("decision"))
+            proof = _redact(fields.get("proof"))
+            next_action = _redact(fields.get("next action"))
+            refs, refs_dropped = _validated_evidence_refs(
+                _extract_evidence_refs(proof, decision)
+            )
+            events.append(
+                WorkflowEvent(
+                    source=SOURCE_GITEA_HANDOFF,
+                    event_type=(
+                        f"handoff:{cth_type.strip()}"
+                        if cth_type_known
+                        else UNKNOWN_HANDOFF_EVENT_TYPE
+                    ),
+                    event_key=f"cth:{kind}:{number}:{comment_id}",
+                    timestamp=_parse_ts(comment.get("created_at")),
+                    actor=_redact((comment.get("user") or {}).get("login")),
+                    role=_redact(fields.get("next owner")),
+                    issue_number=issue_no,
+                    pr_number=pr_no,
+                    # A CTH names its own session when the producer records one;
+                    # it is read from that declared field, never inferred from
+                    # unrelated text.
+                    session_id=_safe_session_id(fields.get("session")),
+                    decision=decision,
+                    message=next_action or _redact(fields.get("status")),
+                    correlation_id=correlation,
+                    evidence_refs=refs,
+                    sensitive=refs_dropped or not cth_type_known,
+                )
+            )
+        except Exception:
+            continue
+    return events
+
+
+# --------------------------------------------------------------------------- #
+# Read-only control-plane event source.                                       #
+# --------------------------------------------------------------------------- #
+
+_CP_EVENTS_QUERY = """
+SELECT e.event_id   AS event_id,
+       e.event_type AS event_type,
+       e.message    AS message,
+       e.created_at AS created_at,
+       w.kind       AS kind,
+       w.number     AS number
+FROM events e
+JOIN work_items w ON e.work_item_id = w.work_item_id
+WHERE w.remote = ? AND w.org = ? AND w.repo = ?
+"""
+
+
+@dataclass(frozen=True)
+class SourceStatus:
+    """Fail-soft status for one timeline source.
+
+    ``supported_filters`` states which filter dimensions this source's records
+    can carry; ``unsupported_filters`` names the requested dimensions it cannot,
+    so an operator can see *why* a source contributed nothing rather than being
+    left to read an empty list as an absence of activity.
+    """
+
+    name: str
+    ok: bool
+    reason: str | None = None
+    count: int = 0
+    supported_filters: tuple[str, ...] = ()
+    unsupported_filters: tuple[str, ...] = ()
+
+    def to_dict(self) -> dict[str, Any]:
+        return {
+            "name": self.name,
+            "ok": self.ok,
+            "reason": self.reason,
+            "count": self.count,
+            "supported_filters": list(self.supported_filters),
+            "unsupported_filters": list(self.unsupported_filters),
+        }
+
+
+def _cp_status(*, ok: bool, reason: str | None = None, count: int = 0) -> SourceStatus:
+    return SourceStatus(
+        SOURCE_CONTROL_PLANE,
+        ok=ok,
+        # A failure reason is serialized like any other field and is often an
+        # exception string carrying a path or a transport error, so it crosses
+        # the redaction boundary too. Static reasons pass through unchanged.
+        reason=_redact(reason),
+        count=count,
+        supported_filters=_SOURCE_FILTER_SUPPORT[SOURCE_CONTROL_PLANE],
+    )
+
+
+def _handoff_status(*, ok: bool, reason: str | None = None, count: int = 0) -> SourceStatus:
+    return SourceStatus(
+        SOURCE_GITEA_HANDOFF,
+        ok=ok,
+        # Same boundary as the control-plane status: this reason can quote an
+        # error raised by a live authenticated fetch.
+        reason=_redact(reason),
+        count=count,
+        supported_filters=_SOURCE_FILTER_SUPPORT[SOURCE_GITEA_HANDOFF],
+    )
+
+
+def read_cp_events(
+    *,
+    remote: str,
+    org: str,
+    repo: str,
+    db_path: str | None = None,
+) -> tuple[list[WorkflowEvent], SourceStatus]:
+    """Read scoped control-plane events read-only. Never creates the DB.
+
+    Opens the SQLite file through a ``mode=ro`` URI: a health/timeline read
+    must never create directories or run the schema migration that
+    ``ControlPlaneDB()`` performs on construction. A missing or unreadable DB
+    degrades to a status with a reason.
+    """
+    path = (db_path or control_plane_db.default_db_path()).strip()
+    conn: sqlite3.Connection | None = None
+    try:
+        conn = sqlite3.connect(f"file:{path}?mode=ro", uri=True)
+        conn.row_factory = sqlite3.Row
+        cursor = conn.execute(_CP_EVENTS_QUERY, (remote, org, repo))
+        rows = [dict(r) for r in cursor.fetchall()]
+    except sqlite3.OperationalError as exc:
+        return ([], _cp_status(ok=False, reason=f"control-plane DB unavailable: {exc}"))
+    except sqlite3.Error as exc:
+        return ([], _cp_status(ok=False, reason=f"control-plane read failed: {exc}"))
+    finally:
+        if conn is not None:
+            conn.close()
+    events = adapt_cp_events(rows)
+    return (events, _cp_status(ok=True, count=len(events)))
+
+
+# --------------------------------------------------------------------------- #
+# Filter, sort, paginate.                                                     #
+# --------------------------------------------------------------------------- #
+
+
+def filter_events(
+    events: Iterable[WorkflowEvent],
+    *,
+    issue: int | None = None,
+    pr: int | None = None,
+    session: str | None = None,
+) -> list[WorkflowEvent]:
+    """Filter events by issue number, PR number, and/or session id.
+
+    Filters are conjunctive. A filter that names a dimension an event does not
+    carry excludes that event (an issue filter excludes PR-only events).
+    """
+    out: list[WorkflowEvent] = []
+    for ev in events:
+        if issue is not None and ev.issue_number != issue:
+            continue
+        if pr is not None and ev.pr_number != pr:
+            continue
+        if session is not None and ev.session_id != session:
+            continue
+        out.append(ev)
+    return out
+
+
+def sort_events(events: Iterable[WorkflowEvent]) -> list[WorkflowEvent]:
+    """Return events in stable timeline order (ascending)."""
+    return sorted(events, key=lambda ev: ev.sort_key())
+
+
+@dataclass(frozen=True)
+class TimelinePage:
+    """One page of the sorted, filtered timeline."""
+
+    events: tuple[WorkflowEvent, ...]
+    total: int
+    limit: int
+    offset: int
+
+    @property
+    def next_offset(self) -> int | None:
+        nxt = self.offset + len(self.events)
+        return nxt if nxt < self.total else None
+
+    def to_dict(self) -> dict[str, Any]:
+        return {
+            "events": [ev.to_dict() for ev in self.events],
+            "pagination": {
+                "total": self.total,
+                "limit": self.limit,
+                "offset": self.offset,
+                "returned": len(self.events),
+                "next_offset": self.next_offset,
+                "has_more": self.next_offset is not None,
+            },
+        }
+
+
+_MAX_LIMIT = 500
+_DEFAULT_LIMIT = 50
+
+
+def _coerce_bounds(limit: int | None, offset: int | None) -> tuple[int, int]:
+    try:
+        lim = int(limit) if limit is not None else _DEFAULT_LIMIT
+    except (TypeError, ValueError):
+        lim = _DEFAULT_LIMIT
+    try:
+        off = int(offset) if offset is not None else 0
+    except (TypeError, ValueError):
+        off = 0
+    lim = max(1, min(lim, _MAX_LIMIT))
+    off = max(0, off)
+    return (lim, off)
+
+
+def paginate(events: list[WorkflowEvent], *, limit: int | None, offset: int | None) -> TimelinePage:
+    lim, off = _coerce_bounds(limit, offset)
+    window = events[off : off + lim]
+    return TimelinePage(events=tuple(window), total=len(events), limit=lim, offset=off)
+
+
+# --------------------------------------------------------------------------- #
+# Composition — load_timeline aggregates all sources, fail-soft.              #
+# --------------------------------------------------------------------------- #
+
+# A comment source is a callable that, given (kind, number), returns the raw
+# Gitea comment list for that issue/PR. The route supplies a live fail-soft
+# fetcher; tests supply a fixture. When None, the handoff source is reported as
+# not-run (never silently empty-and-healthy).
+CommentSource = Callable[[str, int], list[dict[str, Any]]]
+
+
+@dataclass(frozen=True)
+class TimelineSnapshot:
+    """One answered timeline query.
+
+    ``ok`` is False when the query could not be answered as asked — currently
+    when a requested filter dimension no surviving source can carry was
+    supplied. The page is then empty *and* the snapshot says so, because an
+    ``ok`` empty page is a claim that no such activity exists.
+    """
+
+    schema_version: int
+    remote: str
+    org: str
+    repo: str
+    filters: dict[str, Any]
+    page: TimelinePage
+    sources: tuple[SourceStatus, ...]
+    ok: bool = True
+    error: dict[str, Any] | None = None
+
+    def to_dict(self) -> dict[str, Any]:
+        return {
+            "ok": self.ok,
+            "error": self.error,
+            "schema_version": self.schema_version,
+            # Scope and filters are echoed caller input, not derived record
+            # data. Reflecting a value is still emitting it, so both cross the
+            # same boundary; ordinary scope and filter values are unchanged.
+            "scope": {
+                "remote": _safe_echo(self.remote),
+                "org": _safe_echo(self.org),
+                "repo": _safe_echo(self.repo),
+            },
+            "filters": {key: _safe_echo(value) for key, value in self.filters.items()},
+            "sources": [s.to_dict() for s in self.sources],
+            **self.page.to_dict(),
+        }
+
+
+def _unanswerable_reasons(
+    statuses: Iterable[SourceStatus], unanswerable: Iterable[str]
+) -> list[dict[str, str]]:
+    """Explain, per source, why each unanswerable dimension went unanswered."""
+    out: list[dict[str, str]] = []
+    for status in statuses:
+        for dim in unanswerable:
+            if dim not in status.supported_filters:
+                reason = _SOURCE_FILTER_LIMITS.get(
+                    (status.name, dim), f"this source's records carry no {dim} identity"
+                )
+            elif not status.ok:
+                reason = (
+                    f"this source can carry {dim} but did not run: "
+                    f"{status.reason or 'unavailable'}"
+                )
+            else:
+                continue
+            out.append({"source": status.name, "filter": dim, "reason": reason})
+    return out
+
+
+def load_timeline(
+    *,
+    remote: str,
+    org: str,
+    repo: str,
+    issue: int | None = None,
+    pr: int | None = None,
+    session: str | None = None,
+    limit: int | None = None,
+    offset: int | None = None,
+    db_path: str | None = None,
+    comment_source: CommentSource | None = None,
+) -> TimelineSnapshot:
+    """Aggregate every timeline source into one filtered, paginated snapshot.
+
+    Sources are read independently and fail soft: an unavailable source
+    contributes a ``SourceStatus`` with ``ok=False`` and a reason, and never
+    collapses the whole timeline. The handoff source only runs when a specific
+    issue or PR is requested (a handoff comment belongs to one thread) and a
+    ``comment_source`` is available; otherwise it is reported as ``not run``
+    rather than as an empty-and-healthy source.
+
+    A filter dimension that no surviving source can carry — a ``session``
+    filter when the only source that ran is the control plane, whose events
+    record no session — is refused with ``ok=False`` and a structured error
+    instead of being answered with an empty page.
+    """
+    all_events: list[WorkflowEvent] = []
+    statuses: list[SourceStatus] = []
+
+    cp_events, cp_status = read_cp_events(remote=remote, org=org, repo=repo, db_path=db_path)
+    all_events.extend(cp_events)
+    statuses.append(cp_status)
+
+    # Gitea handoff comments are thread-scoped: only fetch when the caller
+    # narrowed to one issue or PR, and only when a source was provided.
+    handoff_target: tuple[str, int] | None = None
+    if pr is not None:
+        handoff_target = ("pr", pr)
+    elif issue is not None:
+        handoff_target = ("issue", issue)
+
+    if handoff_target is None:
+        statuses.append(
+            _handoff_status(
+                ok=False,
+                reason="not run: handoff comments are thread-scoped; filter by issue or pr to include them",
+            )
+        )
+    elif comment_source is None:
+        statuses.append(
+            _handoff_status(
+                ok=False,
+                reason="not run: no comment source configured for this timeline read",
+            )
+        )
+    else:
+        kind, number = handoff_target
+        try:
+            comments = comment_source(kind, number) or []
+            handoff_events = adapt_cth_comments(comments, kind=kind, number=number)
+            all_events.extend(handoff_events)
+            statuses.append(_handoff_status(ok=True, count=len(handoff_events)))
+        except Exception as exc:  # fail soft: a fetch/parse error degrades this source only
+            statuses.append(_handoff_status(ok=False, reason=f"handoff source failed: {exc}"))
+
+    requested = tuple(
+        name
+        for name, value in ((FILTER_ISSUE, issue), (FILTER_PR, pr), (FILTER_SESSION, session))
+        if value is not None
+    )
+    statuses = [
+        replace(
+            status,
+            unsupported_filters=tuple(
+                dim for dim in requested if dim not in status.supported_filters
+            ),
+        )
+        for status in statuses
+    ]
+    filters = {"issue": issue, "pr": pr, "session": session}
+
+    # A dimension is answerable only if a source that actually ran can carry it.
+    # If none can, refuse: an empty page would assert "no such activity", which
+    # is a claim this timeline is not in a position to make.
+    answerable: set[str] = set()
+    for status in statuses:
+        if status.ok:
+            answerable.update(status.supported_filters)
+    unanswerable = tuple(dim for dim in requested if dim not in answerable)
+
+    if unanswerable:
+        return TimelineSnapshot(
+            schema_version=TIMELINE_SCHEMA_VERSION,
+            remote=remote,
+            org=org,
+            repo=repo,
+            filters=filters,
+            page=paginate([], limit=limit, offset=offset),
+            sources=tuple(statuses),
+            ok=False,
+            error={
+                "code": "filter_not_supported",
+                "unsupported_filters": list(unanswerable),
+                "detail": (
+                    "no timeline source that ran can answer "
+                    + ", ".join(f"'{dim}'" for dim in unanswerable)
+                    + "; the result is refused rather than returned empty"
+                ),
+                "sources": _unanswerable_reasons(statuses, unanswerable),
+            },
+        )
+
+    filtered = filter_events(all_events, issue=issue, pr=pr, session=session)
+    ordered = sort_events(filtered)
+    page = paginate(ordered, limit=limit, offset=offset)
+
+    return TimelineSnapshot(
+        schema_version=TIMELINE_SCHEMA_VERSION,
+        remote=remote,
+        org=org,
+        repo=repo,
+        filters=filters,
+        page=page,
+        sources=tuple(statuses),
+    )
+
+
+def snapshot_to_dict(snapshot: TimelineSnapshot) -> dict[str, Any]:
+    return snapshot.to_dict()