Merge branch 'master' into feat/issue-637-timeline-model

Remediates the two blocking findings in review #522 on PR #849.

F1 — the session filter dimension was dead end to end. No source could
produce an event carrying a session identifier, so filter_events dropped
every event whenever session was supplied and the API answered with a
green, empty page. An empty result reads to an operator as "no such
session activity", which is a stronger and false claim.

Each source now declares which filter dimensions its records can actually
carry. The control-plane events table is (event_id, work_item_id,
event_type, message, created_at) and records no session, so that source
declares the session dimension unsupported rather than pretending to
answer it; the dead read of a non-existent session_id column is removed.
A CTH handoff comment declares its own Session field, so the handoff
adapter populates session_id from that declared field — authoritative
source data, never inferred from an actor, work item, or message text.

When no source that ran can carry a requested dimension, load_timeline
refuses with ok=false and a structured error naming the unsupported
filters and the per-source reason, and the route answers 422. A source
that can answer the dimension and simply matched nothing still returns
200 with an honest empty page. Ordering, pagination, and the issue/PR
filters are unchanged.

F2 — evidence_refs bypassed redaction and could emit a credential
verbatim. proof and decision were passed to _extract_evidence_refs before
redaction, and the SHA pattern matched any 7-40 character lowercase hex
run, which is exactly the shape of a Gitea access token.

Redaction now runs first and every derived value is taken from the
redacted text. A commit reference is recognised only where the source
text declares one (commit, head, base, sha, ...), so an undeclared hex
run is never lifted out of prose into a structured field; this also drops
the ordinary-word noise the reviewer noted. Every reference is then
independently revalidated against an allowed shape and a second redaction
pass immediately before serialization, failing closed by dropping
anything unproven and flagging the event sensitive. Actor is redacted for
the same reason, and a secret-shaped session value is dropped rather than
emitted. Legitimate issue, PR, short-SHA and full 40-character SHA
references stay usable.

Tests: 16 added. Session filtering is now driven through the CTH adapter
and the composed load_timeline/API path rather than a hand-built
WorkflowEvent, covering a match, an honest empty result, pagination and
ordering under the filter, the 422 refusal, and the per-source support
declaration. Redaction coverage asserts a synthetic 40-character hex
value (not a real credential) appears nowhere in the complete serialized
payload including evidence_refs, that the independent revalidation drops
unproven references, and that legitimate references still resolve.

pytest tests/test_webui_timeline.py: 42 passed (was 26).
pytest -k webui: 340 passed, 270 subtests passed (was 324).
Full suite: 4607 passed, 12 failed, 6 skipped, 684 subtests passed — the
same 12 failures as the master baseline, none under webui/.

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

docs/webui-local-dev.md

@@ -292,6 +292,108 @@ 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

pr_work_lease.py

@@ -228,74 +228,25 @@ def find_active_reviewer_lease(
     return None
 
 
-def _conflict_fix_chain_key(lease: dict) -> tuple | None:
-    """Identity of the lease chain a conflict-fix marker belongs to (#842).
-
-    Keyed by PR number, profile, head_before, and branch. Returns None when any
-    required component (pr_number, profile, head_before) is missing or malformed.
-    """
-    raw = lease.get("raw_fields") or {}
-    pr_number = lease.get("pr_number")
-    profile = (lease.get("profile") or "").strip().lower()
-    head_before = lease.get("head_before")
-    branch = (lease.get("branch") or raw.get("branch") or "").strip()
-    if not (pr_number and profile and head_before):
-        return None
-    return (pr_number, profile, head_before, branch)
-
-
-def _conflict_fix_chain_matches(key1: tuple, key2: tuple) -> bool:
-    """True when two conflict-fix chain keys refer to the same lease chain."""
-    pr1, profile1, head1, branch1 = key1
-    pr2, profile2, head2, branch2 = key2
-    if pr1 != pr2 or profile1 != profile2 or head1 != head2:
-        return False
-    if branch1 and branch2 and branch1 != branch2:
-        return False
-    return True
-
-
-def _conflict_fix_chain_terminated_after(entries: list[dict], index: int) -> bool:
-    """True when a later marker terminates the conflict-fix chain of ``entries[index]``.
-
-    Append-only newest-wins: a terminal marker (phase=released/blocked/done)
-    ends only its matching claim chain (#842).
-    """
-    key = _conflict_fix_chain_key(entries[index])
-    if key is None:
-        return False
-    for later in entries[index + 1:]:
-        phase = (later.get("phase") or "").strip().lower()
-        if phase not in _TERMINAL_CONFLICT_FIX_PHASES:
-            continue
-        later_key = _conflict_fix_chain_key(later)
-        if later_key and _conflict_fix_chain_matches(key, later_key):
-            return True
-    return False
-
-
 def find_active_conflict_fix_lease(
     comments: list[dict],
     *,
     pr_number: int,
     now: datetime | None = None,
 ) -> dict[str, Any] | None:
-    """Return the newest unexpired, non-terminated conflict-fix lease for *pr_number*, if any."""
+    """Return the newest unexpired conflict-fix lease for *pr_number*, if any."""
     now = now or datetime.now(timezone.utc)
     candidates = [
         entry for entry in _comment_entries(comments, pr_number=pr_number)
         if entry.get("lease_kind") == "conflict_fix"
     ]
-    for index in range(len(candidates) - 1, -1, -1):
+    for lease in reversed(candidates):
-        lease = candidates[index]
         if _lease_expired(lease, now=now):
             continue
         phase = (lease.get("phase") or "").strip().lower()
         if phase in _TERMINAL_CONFLICT_FIX_PHASES:
             continue
         if phase in _ACTIVE_CONFLICT_FIX_PHASES or phase:
-            if _conflict_fix_chain_terminated_after(candidates, index):
-                continue
             return lease
     return None
 

tests/test_pr_work_lease.py

@@ -19,7 +19,6 @@ from pr_work_lease import (  # noqa: E402
     assess_reviewer_mutation_blocked,
     assess_reviewer_stale_head_final_report,
     format_conflict_fix_lease_body,
-    find_active_conflict_fix_lease,
     parse_conflict_fix_lease_comment,
     parse_reviewer_lease_comment,
 )
@@ -204,157 +203,5 @@ class TestFormatLease(unittest.TestCase):
         self.assertEqual(parsed["pr_number"], 376)
 
 
-class TestConflictFixLeaseLifecycle(unittest.TestCase):
-    def test_claim_followed_by_matching_release(self):
-        claim_body = _conflict_fix_body(phase="claimed", worktree="branches/fix-376")
-        expires = (NOW + timedelta(minutes=60)).isoformat().replace("+00:00", "Z")
-        release_body = "\n".join([
-            CONFLICT_FIX_LEASE_MARKER,
-            "pr: #376",
-            "branch: feat/fix-376",
-            "worktree: branches/fix-376",
-            "profile: prgs-author",
-            "phase: released",
-            f"head_before: {HEAD_A}",
-            f"head_after: {HEAD_B}",
-            f"expires_at: {expires}",
-        ])
-        comments = [{"body": claim_body}, {"body": release_body}]
-        lease = find_active_conflict_fix_lease(comments, pr_number=376, now=NOW)
-        self.assertIsNone(lease)
-
-    def test_expired_claim_without_release(self):
-        past_expires = (NOW - timedelta(minutes=10)).isoformat().replace("+00:00", "Z")
-        claim_body = "\n".join([
-            CONFLICT_FIX_LEASE_MARKER,
-            "pr: #376",
-            "phase: claimed",
-            f"head_before: {HEAD_A}",
-            f"expires_at: {past_expires}",
-            "profile: prgs-author",
-        ])
-        comments = [{"body": claim_body}]
-        lease = find_active_conflict_fix_lease(comments, pr_number=376, now=NOW)
-        self.assertIsNone(lease)
-
-    def test_mismatched_release_different_head(self):
-        claim_body = _conflict_fix_body(phase="claimed", worktree="branches/fix-376")
-        expires = (NOW + timedelta(minutes=60)).isoformat().replace("+00:00", "Z")
-        release_body = "\n".join([
-            CONFLICT_FIX_LEASE_MARKER,
-            "pr: #376",
-            "profile: prgs-author",
-            "phase: released",
-            f"head_before: {HEAD_B}",
-            f"expires_at: {expires}",
-        ])
-        comments = [{"body": claim_body}, {"body": release_body}]
-        lease = find_active_conflict_fix_lease(comments, pr_number=376, now=NOW)
-        self.assertIsNotNone(lease)
-        self.assertEqual(lease["phase"], "claimed")
-
-    def test_mismatched_release_different_branch(self):
-        claim_body = "\n".join([
-            CONFLICT_FIX_LEASE_MARKER,
-            "pr: #376",
-            "branch: feat/branch-A",
-            "phase: claimed",
-            f"head_before: {HEAD_A}",
-            f"expires_at: {(NOW + timedelta(minutes=60)).isoformat().replace('+00:00', 'Z')}",
-            "profile: prgs-author",
-        ])
-        release_body = "\n".join([
-            CONFLICT_FIX_LEASE_MARKER,
-            "pr: #376",
-            "branch: feat/branch-B",
-            "phase: released",
-            f"head_before: {HEAD_A}",
-            f"expires_at: {(NOW + timedelta(minutes=60)).isoformat().replace('+00:00', 'Z')}",
-            "profile: prgs-author",
-        ])
-        comments = [{"body": claim_body}, {"body": release_body}]
-        lease = find_active_conflict_fix_lease(comments, pr_number=376, now=NOW)
-        self.assertIsNotNone(lease)
-        self.assertEqual(lease["phase"], "claimed")
-
-    def test_release_followed_by_newer_claim(self):
-        claim_1 = _conflict_fix_body(phase="claimed", worktree="branches/fix-376")
-        expires = (NOW + timedelta(minutes=60)).isoformat().replace("+00:00", "Z")
-        release_1 = "\n".join([
-            CONFLICT_FIX_LEASE_MARKER,
-            "pr: #376",
-            "profile: prgs-author",
-            "phase: released",
-            f"head_before: {HEAD_A}",
-            f"head_after: {HEAD_B}",
-            f"expires_at: {expires}",
-        ])
-        claim_2 = "\n".join([
-            CONFLICT_FIX_LEASE_MARKER,
-            "pr: #376",
-            "profile: prgs-author",
-            "phase: claimed",
-            f"head_before: {HEAD_B}",
-            f"expires_at: {expires}",
-        ])
-        comments = [{"body": claim_1}, {"body": release_1}, {"body": claim_2}]
-        lease = find_active_conflict_fix_lease(comments, pr_number=376, now=NOW)
-        self.assertIsNotNone(lease)
-        self.assertEqual(lease["head_before"], HEAD_B)
-
-    def test_malformed_or_ambiguous_markers(self):
-        malformed_release = "\n".join([
-            CONFLICT_FIX_LEASE_MARKER,
-            "pr: #376",
-            "phase: released",
-            # missing head_before and profile
-        ])
-        claim_body = _conflict_fix_body(phase="claimed")
-        comments = [{"body": claim_body}, {"body": malformed_release}]
-        lease = find_active_conflict_fix_lease(comments, pr_number=376, now=NOW)
-        self.assertIsNotNone(lease)
-
-    def test_pr818_historical_sequence(self):
-        comment_14696 = "\n".join([
-            "<!-- mcp-conflict-fix-lease:v1 -->",
-            "pr: #818",
-            "branch: feat/issue-638-webui-app-shell-phase1",
-            "worktree: /Users/jasonwalker/Development/Gitea-Tools/branches/issue-638-webui-app-shell-phase1",
-            "profile: prgs-author",
-            "session_id: unknown",
-            "phase: claimed",
-            "head_before: 08061b7b8aebdd099a37d1abf5dafcf38e4fd3fb",
-            "expires_at: 2026-07-23T07:12:13Z",
-            "reviewer_active: no",
-        ])
-        comment_14730 = "\n".join([
-            "<!-- mcp-conflict-fix-lease:v1 -->",
-            "pr: #818",
-            "branch: feat/issue-638-webui-app-shell-phase1",
-            "worktree: /Users/jasonwalker/Development/Gitea-Tools/branches/issue-638-webui-app-shell-phase1",
-            "profile: prgs-author",
-            "session_id: prgs-author-61241-e5129c60",
-            "phase: released",
-            "head_before: 08061b7b8aebdd099a37d1abf5dafcf38e4fd3fb",
-            "head_after: 64b6eb5d5402663098de5ded3b0617cc3b3df98f",
-            "expires_at: 2026-07-23T06:05:00Z",
-            "reviewer_active: no",
-        ])
-        comments = [{"body": comment_14696}, {"body": comment_14730}]
-        check_now = datetime(2026, 7, 23, 6, 30, tzinfo=timezone.utc)
-        lease = find_active_conflict_fix_lease(comments, pr_number=818, now=check_now)
-        self.assertIsNone(lease)
-        
-        reviewer_gate = assess_reviewer_mutation_blocked(
-            pr_number=818,
-            comments=comments,
-            reviewed_head_sha="64b6eb5d5402663098de5ded3b0617cc3b3df98f",
-            live_head_sha="64b6eb5d5402663098de5ded3b0617cc3b3df98f",
-            mutation="approve",
-            now=check_now,
-        )
-        self.assertTrue(reviewer_gate["mutation_allowed"])
-
-
 if __name__ == "__main__":
     unittest.main()

tests/test_webui_timeline.py

@@ -0,0 +1,618 @@
+"""Tests for the workflow-event timeline model and read API (#637).
+
+Covers the acceptance criteria: versioned schema, adaptation of control-plane
+events and Gitea handoff comments, filter by issue/PR/session, redaction of
+secret-like payloads, and stable pagination.
+"""
+import json
+import os
+import sqlite3
+import sys
+import unittest
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
+
+from starlette.testclient import TestClient
+
+import control_plane_db
+from canonical_thread_handoff import format_cth_body
+from webui import timeline
+from webui.app import create_app
+
+
+def _seed_db(path: str) -> None:
+    """Create a control-plane DB and seed scoped work_items + events."""
+    # Constructing ControlPlaneDB runs the schema migration once.
+    control_plane_db.ControlPlaneDB(db_path=path)
+    conn = sqlite3.connect(path)
+    try:
+        conn.execute(
+            "INSERT INTO work_items(remote, org, repo, kind, number, state, updated_at) "
+            "VALUES (?,?,?,?,?,?,?)",
+            ("prgs", "Scaled-Tech-Consulting", "Gitea-Tools", "issue", 637, "open", "2026-07-23T00:00:00Z"),
+        )
+        issue_wid = conn.execute("SELECT last_insert_rowid()").fetchone()[0]
+        conn.execute(
+            "INSERT INTO work_items(remote, org, repo, kind, number, state, updated_at) "
+            "VALUES (?,?,?,?,?,?,?)",
+            ("prgs", "Scaled-Tech-Consulting", "Gitea-Tools", "pr", 813, "open", "2026-07-23T00:00:00Z"),
+        )
+        pr_wid = conn.execute("SELECT last_insert_rowid()").fetchone()[0]
+        # A work item for a different repo — must never appear in prgs/Gitea-Tools scope.
+        conn.execute(
+            "INSERT INTO work_items(remote, org, repo, kind, number, state, updated_at) "
+            "VALUES (?,?,?,?,?,?,?)",
+            ("dadeschools", "Other", "Elsewhere", "issue", 1, "open", "2026-07-23T00:00:00Z"),
+        )
+        other_wid = conn.execute("SELECT last_insert_rowid()").fetchone()[0]
+
+        rows = [
+            (issue_wid, "allocation", "assigned author work", "2026-07-23T01:00:00Z"),
+            (issue_wid, "lease.renew", "token=ghs_ABCDEF1234567890abcdef lease renewed", "2026-07-23T02:00:00Z"),
+            (pr_wid, "pr.opened", "PR opened for review", "2026-07-23T03:00:00Z"),
+            (other_wid, "allocation", "off-scope event", "2026-07-23T04:00:00Z"),
+        ]
+        conn.executemany(
+            "INSERT INTO events(work_item_id, event_type, message, created_at) VALUES (?,?,?,?)",
+            rows,
+        )
+        conn.commit()
+    finally:
+        conn.close()
+
+
+class TestSchema(unittest.TestCase):
+    def test_schema_is_versioned(self):
+        self.assertIsInstance(timeline.TIMELINE_SCHEMA_VERSION, int)
+        self.assertGreaterEqual(timeline.TIMELINE_SCHEMA_VERSION, 1)
+
+    def test_event_to_dict_shape(self):
+        ev = timeline.WorkflowEvent(
+            source=timeline.SOURCE_CONTROL_PLANE,
+            event_type="allocation",
+            event_key="cp:1",
+            timestamp="2026-07-23T01:00:00Z",
+            issue_number=637,
+        )
+        d = ev.to_dict()
+        for key in (
+            "source", "event_type", "event_key", "timestamp", "actor", "role",
+            "issue_number", "pr_number", "session_id", "tool_name", "decision",
+            "message", "correlation_id", "evidence_refs", "sensitive",
+        ):
+            self.assertIn(key, d)
+        self.assertEqual(d["evidence_refs"], [])
+
+
+class TestCpAdapter(unittest.TestCase):
+    def test_issue_and_pr_mapping(self):
+        rows = [
+            {"event_id": 1, "event_type": "allocation", "message": "x", "created_at": "2026-07-23T01:00:00Z", "kind": "issue", "number": 637},
+            {"event_id": 2, "event_type": "pr.opened", "message": "y", "created_at": "2026-07-23T02:00:00Z", "kind": "pr", "number": 813},
+        ]
+        events = timeline.adapt_cp_events(rows)
+        self.assertEqual(len(events), 2)
+        self.assertEqual(events[0].issue_number, 637)
+        self.assertIsNone(events[0].pr_number)
+        self.assertEqual(events[0].correlation_id, "issue#637")
+        self.assertIsNone(events[1].issue_number)
+        self.assertEqual(events[1].pr_number, 813)
+
+    def test_malformed_rows_skipped(self):
+        rows = [
+            {"event_id": None, "event_type": "x", "kind": "issue", "number": 1},
+            {"event_id": 5, "event_type": "", "kind": "issue", "number": 1},
+            {"event_id": 6, "event_type": "ok", "message": "m", "created_at": None, "kind": "issue", "number": 1},
+        ]
+        events = timeline.adapt_cp_events(rows)
+        self.assertEqual(len(events), 1)
+        self.assertIsNone(events[0].timestamp)
+
+    def test_sensitive_event_flagged(self):
+        rows = [{"event_id": 1, "event_type": "lease.renew", "message": "m", "created_at": "2026-07-23T01:00:00Z", "kind": "issue", "number": 1}]
+        events = timeline.adapt_cp_events(rows)
+        self.assertTrue(events[0].sensitive)
+
+
+class TestCthAdapter(unittest.TestCase):
+    def test_cth_comment_becomes_event(self):
+        body = format_cth_body(
+            cth_type="Author Handoff",
+            status="ready",
+            next_owner="reviewer",
+            decision="implement timeline",
+            proof="commit abc1234 closes #637",
+            next_action="review PR",
+            ready_to_paste_prompt="Review PR #900 as reviewer",
+        )
+        comments = [{"id": 42, "body": body, "created_at": "2026-07-23T05:00:00Z", "user": {"login": "jcwalker3"}}]
+        events = timeline.adapt_cth_comments(comments, kind="issue", number=637)
+        self.assertEqual(len(events), 1)
+        ev = events[0]
+        self.assertEqual(ev.source, timeline.SOURCE_GITEA_HANDOFF)
+        self.assertEqual(ev.event_type, "handoff:Author Handoff")
+        self.assertEqual(ev.actor, "jcwalker3")
+        self.assertEqual(ev.issue_number, 637)
+        self.assertEqual(ev.event_key, "cth:issue:637:42")
+        self.assertIn("#637", ev.evidence_refs)
+        self.assertIn("abc1234", ev.evidence_refs)
+
+    def test_non_cth_comment_ignored(self):
+        comments = [{"id": 1, "body": "just a normal comment", "created_at": "2026-07-23T05:00:00Z", "user": {"login": "x"}}]
+        self.assertEqual(timeline.adapt_cth_comments(comments, kind="issue", number=1), [])
+
+
+class TestRedaction(unittest.TestCase):
+    def test_cp_message_redacted(self):
+        rows = [{"event_id": 1, "event_type": "lease", "message": "token=ghs_ABCDEF1234567890abcdef here", "created_at": "2026-07-23T01:00:00Z", "kind": "issue", "number": 1}]
+        events = timeline.adapt_cp_events(rows)
+        self.assertNotIn("ghs_ABCDEF1234567890abcdef", events[0].message or "")
+
+    def test_handoff_decision_redacted(self):
+        body = format_cth_body(
+            cth_type="Blocker",
+            status="blocked",
+            next_owner="author",
+            decision="password=SuperSecret123! must rotate",
+            proof="none",
+            next_action="rotate",
+            ready_to_paste_prompt="Rotate the credential and retry",
+        )
+        comments = [{"id": 7, "body": body, "created_at": "2026-07-23T05:00:00Z", "user": {"login": "x"}}]
+        events = timeline.adapt_cth_comments(comments, kind="issue", number=1)
+        self.assertNotIn("SuperSecret123!", events[0].decision or "")
+
+
+class TestFilterSortPaginate(unittest.TestCase):
+    def _events(self):
+        return [
+            timeline.WorkflowEvent(source="control_plane", event_type="a", event_key="cp:3", timestamp="2026-07-23T03:00:00Z", pr_number=813),
+            timeline.WorkflowEvent(source="control_plane", event_type="b", event_key="cp:1", timestamp="2026-07-23T01:00:00Z", issue_number=637),
+            timeline.WorkflowEvent(source="control_plane", event_type="c", event_key="cp:2", timestamp="2026-07-23T02:00:00Z", issue_number=637, session_id="sess-1"),
+        ]
+
+    def test_filter_by_issue(self):
+        out = timeline.filter_events(self._events(), issue=637)
+        self.assertEqual({e.event_key for e in out}, {"cp:1", "cp:2"})
+
+    def test_filter_by_pr(self):
+        out = timeline.filter_events(self._events(), pr=813)
+        self.assertEqual([e.event_key for e in out], ["cp:3"])
+
+    def test_filter_by_session(self):
+        out = timeline.filter_events(self._events(), session="sess-1")
+        self.assertEqual([e.event_key for e in out], ["cp:2"])
+
+    def test_stable_sort_ascending(self):
+        out = timeline.sort_events(self._events())
+        self.assertEqual([e.event_key for e in out], ["cp:1", "cp:2", "cp:3"])
+
+    def test_missing_timestamp_sorts_last(self):
+        evs = self._events() + [
+            timeline.WorkflowEvent(source="control_plane", event_type="z", event_key="cp:9", timestamp=None)
+        ]
+        out = timeline.sort_events(evs)
+        self.assertEqual(out[-1].event_key, "cp:9")
+
+    def test_pagination_windows_and_next_offset(self):
+        evs = timeline.sort_events(self._events())
+        page1 = timeline.paginate(evs, limit=2, offset=0)
+        self.assertEqual(len(page1.events), 2)
+        self.assertEqual(page1.total, 3)
+        self.assertEqual(page1.next_offset, 2)
+        page2 = timeline.paginate(evs, limit=2, offset=2)
+        self.assertEqual(len(page2.events), 1)
+        self.assertIsNone(page2.next_offset)
+
+    def test_pagination_bounds_coerced(self):
+        evs = self._events()
+        page = timeline.paginate(evs, limit=-5, offset=-3)
+        self.assertGreaterEqual(page.limit, 1)
+        self.assertEqual(page.offset, 0)
+
+
+class TestCpReader(unittest.TestCase):
+    def test_reads_scoped_events_only(self):
+        import tempfile
+
+        with tempfile.TemporaryDirectory() as tmp:
+            db = os.path.join(tmp, "cp.sqlite3")
+            _seed_db(db)
+            events, status = timeline.read_cp_events(
+                remote="prgs", org="Scaled-Tech-Consulting", repo="Gitea-Tools", db_path=db
+            )
+            self.assertTrue(status.ok)
+            # 3 scoped events; the dadeschools/Other event is excluded.
+            self.assertEqual(len(events), 3)
+            self.assertTrue(all(e.source == "control_plane" for e in events))
+            # Redaction applied to the token-bearing message.
+            joined = " ".join(e.message or "" for e in events)
+            self.assertNotIn("ghs_ABCDEF1234567890abcdef", joined)
+
+    def test_missing_db_degrades(self):
+        events, status = timeline.read_cp_events(
+            remote="prgs", org="Scaled-Tech-Consulting", repo="Gitea-Tools",
+            db_path="/nonexistent/path/to/cp.sqlite3",
+        )
+        self.assertEqual(events, [])
+        self.assertFalse(status.ok)
+        self.assertIsNotNone(status.reason)
+
+
+class TestLoadTimeline(unittest.TestCase):
+    def test_handoff_not_run_without_thread_filter(self):
+        import tempfile
+
+        with tempfile.TemporaryDirectory() as tmp:
+            db = os.path.join(tmp, "cp.sqlite3")
+            _seed_db(db)
+            snap = timeline.load_timeline(
+                remote="prgs", org="Scaled-Tech-Consulting", repo="Gitea-Tools", db_path=db
+            )
+            d = snap.to_dict()
+            handoff = [s for s in d["sources"] if s["name"] == "gitea_handoff"][0]
+            self.assertFalse(handoff["ok"])
+            self.assertIn("thread-scoped", handoff["reason"])
+            self.assertEqual(d["schema_version"], timeline.TIMELINE_SCHEMA_VERSION)
+
+    def test_handoff_included_via_injected_source(self):
+        import tempfile
+
+        body = format_cth_body(
+            cth_type="Author Handoff", status="ready", next_owner="reviewer",
+            decision="d", proof="#637", next_action="review", ready_to_paste_prompt="Review PR #1 now",
+        )
+
+        def source(kind, number):
+            return [{"id": 1, "body": body, "created_at": "2026-07-23T09:00:00Z", "user": {"login": "jcwalker3"}}]
+
+        with tempfile.TemporaryDirectory() as tmp:
+            db = os.path.join(tmp, "cp.sqlite3")
+            _seed_db(db)
+            snap = timeline.load_timeline(
+                remote="prgs", org="Scaled-Tech-Consulting", repo="Gitea-Tools",
+                issue=637, db_path=db, comment_source=source,
+            )
+            d = snap.to_dict()
+            handoff = [s for s in d["sources"] if s["name"] == "gitea_handoff"][0]
+            self.assertTrue(handoff["ok"])
+            self.assertEqual(handoff["count"], 1)
+            # Both a CP event and the handoff event for issue 637 appear, sorted.
+            kinds = {e["source"] for e in d["events"]}
+            self.assertEqual(kinds, {"control_plane", "gitea_handoff"})
+
+    def test_failing_comment_source_degrades_only_handoff(self):
+        import tempfile
+
+        def boom(kind, number):
+            raise RuntimeError("network down")
+
+        with tempfile.TemporaryDirectory() as tmp:
+            db = os.path.join(tmp, "cp.sqlite3")
+            _seed_db(db)
+            snap = timeline.load_timeline(
+                remote="prgs", org="Scaled-Tech-Consulting", repo="Gitea-Tools",
+                issue=637, db_path=db, comment_source=boom,
+            )
+            d = snap.to_dict()
+            cp = [s for s in d["sources"] if s["name"] == "control_plane"][0]
+            handoff = [s for s in d["sources"] if s["name"] == "gitea_handoff"][0]
+            self.assertTrue(cp["ok"])
+            self.assertFalse(handoff["ok"])
+            self.assertIn("network down", handoff["reason"])
+
+
+# A fabricated 40-character lowercase hex value with the shape of a Gitea
+# personal access token. Never a real credential — its only job is to prove it
+# cannot reach any part of a serialized timeline payload.
+SYNTHETIC_SECRET_40_HEX = "a3f9c17be44d2058e6b17c9d0f5321ab77c4e9d1"
+
+
+def _cth_comment(comment_id, *, created_at, session=None, decision="d", proof="none", **kw):
+    """Build one real CTH comment record, optionally declaring a session."""
+    extra = {"Session": session} if session is not None else None
+    body = format_cth_body(
+        cth_type=kw.pop("cth_type", "Author Handoff"),
+        status=kw.pop("status", "ready"),
+        next_owner=kw.pop("next_owner", "reviewer"),
+        decision=decision,
+        proof=proof,
+        next_action=kw.pop("next_action", "review"),
+        ready_to_paste_prompt=kw.pop("ready_to_paste_prompt", "Review PR #1 now"),
+        extra_fields=extra,
+    )
+    return {
+        "id": comment_id,
+        "body": body,
+        "created_at": created_at,
+        "user": {"login": kw.pop("login", "jcwalker3")},
+    }
+
+
+class TestSessionFilterThroughAdapter(unittest.TestCase):
+    """F1: the session dimension must be real, or explicitly refused.
+
+    These drive the filter through the CTH adapter and the composed
+    ``load_timeline``/API path, never through a hand-built ``WorkflowEvent``.
+    """
+
+    def _source(self, comments):
+        return lambda kind, number: list(comments)
+
+    def test_adapter_populates_declared_session(self):
+        events = timeline.adapt_cth_comments(
+            [_cth_comment(1, created_at="2026-07-23T05:00:00Z", session="sess-alpha")],
+            kind="issue",
+            number=637,
+        )
+        self.assertEqual(len(events), 1)
+        self.assertEqual(events[0].session_id, "sess-alpha")
+
+    def test_session_filter_matches_through_adapter(self):
+        import tempfile
+
+        comments = [
+            _cth_comment(1, created_at="2026-07-23T09:00:00Z", session="sess-alpha"),
+            _cth_comment(2, created_at="2026-07-23T08:00:00Z", session="sess-alpha"),
+            _cth_comment(3, created_at="2026-07-23T10:00:00Z", session="sess-beta"),
+        ]
+        with tempfile.TemporaryDirectory() as tmp:
+            db = os.path.join(tmp, "cp.sqlite3")
+            _seed_db(db)
+            snap = timeline.load_timeline(
+                remote="prgs", org="Scaled-Tech-Consulting", repo="Gitea-Tools",
+                issue=637, session="sess-alpha", db_path=db,
+                comment_source=self._source(comments),
+            )
+            d = snap.to_dict()
+            self.assertTrue(d["ok"])
+            self.assertIsNone(d["error"])
+            keys = [e["event_key"] for e in d["events"]]
+            # Only the two sess-alpha events, still in ascending timestamp order.
+            self.assertEqual(keys, ["cth:issue:637:2", "cth:issue:637:1"])
+            self.assertTrue(all(e["session_id"] == "sess-alpha" for e in d["events"]))
+            self.assertEqual(d["pagination"]["total"], 2)
+
+    def test_session_filter_paginates_and_keeps_order(self):
+        import tempfile
+
+        comments = [
+            _cth_comment(i, created_at=f"2026-07-23T0{i}:00:00Z", session="sess-alpha")
+            for i in range(1, 4)
+        ]
+        with tempfile.TemporaryDirectory() as tmp:
+            db = os.path.join(tmp, "cp.sqlite3")
+            _seed_db(db)
+            kwargs = dict(
+                remote="prgs", org="Scaled-Tech-Consulting", repo="Gitea-Tools",
+                issue=637, session="sess-alpha", db_path=db,
+                comment_source=self._source(comments),
+            )
+            page1 = timeline.load_timeline(limit=2, offset=0, **kwargs).to_dict()
+            page2 = timeline.load_timeline(limit=2, offset=2, **kwargs).to_dict()
+            self.assertEqual(
+                [e["event_key"] for e in page1["events"]],
+                ["cth:issue:637:1", "cth:issue:637:2"],
+            )
+            self.assertEqual(page1["pagination"]["next_offset"], 2)
+            self.assertEqual([e["event_key"] for e in page2["events"]], ["cth:issue:637:3"])
+            self.assertIsNone(page2["pagination"]["next_offset"])
+
+    def test_unknown_session_is_honestly_empty_when_supported(self):
+        """A source that *can* answer the dimension may legitimately match nothing."""
+        import tempfile
+
+        comments = [_cth_comment(1, created_at="2026-07-23T09:00:00Z", session="sess-alpha")]
+        with tempfile.TemporaryDirectory() as tmp:
+            db = os.path.join(tmp, "cp.sqlite3")
+            _seed_db(db)
+            d = timeline.load_timeline(
+                remote="prgs", org="Scaled-Tech-Consulting", repo="Gitea-Tools",
+                issue=637, session="sess-nope", db_path=db,
+                comment_source=self._source(comments),
+            ).to_dict()
+            self.assertTrue(d["ok"])
+            self.assertEqual(d["events"], [])
+
+    def test_session_filter_refused_when_no_source_can_answer(self):
+        """The F1 defect: an empty-and-healthy page for an unanswerable filter."""
+        import tempfile
+
+        with tempfile.TemporaryDirectory() as tmp:
+            db = os.path.join(tmp, "cp.sqlite3")
+            _seed_db(db)
+            d = timeline.load_timeline(
+                remote="prgs", org="Scaled-Tech-Consulting", repo="Gitea-Tools",
+                issue=637, session="sess-alpha", db_path=db, comment_source=None,
+            ).to_dict()
+            self.assertFalse(d["ok"])
+            self.assertEqual(d["error"]["code"], "filter_not_supported")
+            self.assertEqual(d["error"]["unsupported_filters"], ["session"])
+            self.assertEqual(d["events"], [])
+            self.assertEqual(d["pagination"]["total"], 0)
+            # The refusal states which source could not answer, and why.
+            explained = {r["source"] for r in d["error"]["sources"]}
+            self.assertEqual(explained, {"control_plane", "gitea_handoff"})
+
+    def test_control_plane_declares_session_unsupported(self):
+        import tempfile
+
+        with tempfile.TemporaryDirectory() as tmp:
+            db = os.path.join(tmp, "cp.sqlite3")
+            _seed_db(db)
+            d = timeline.load_timeline(
+                remote="prgs", org="Scaled-Tech-Consulting", repo="Gitea-Tools",
+                issue=637, session="sess-alpha", db_path=db,
+                comment_source=self._source([]),
+            ).to_dict()
+            cp = [s for s in d["sources"] if s["name"] == "control_plane"][0]
+            handoff = [s for s in d["sources"] if s["name"] == "gitea_handoff"][0]
+            self.assertNotIn("session", cp["supported_filters"])
+            self.assertEqual(cp["unsupported_filters"], ["session"])
+            self.assertIn("session", handoff["supported_filters"])
+            self.assertEqual(handoff["unsupported_filters"], [])
+
+    def test_secret_shaped_session_value_is_dropped(self):
+        events = timeline.adapt_cth_comments(
+            [_cth_comment(1, created_at="2026-07-23T05:00:00Z", session=SYNTHETIC_SECRET_40_HEX)],
+            kind="issue",
+            number=637,
+        )
+        self.assertIsNone(events[0].session_id)
+        self.assertNotIn(SYNTHETIC_SECRET_40_HEX, json.dumps(events[0].to_dict()))
+
+
+class TestEvidenceRefRedaction(unittest.TestCase):
+    """F2: evidence_refs must not be a hole in the redaction boundary."""
+
+    def _refs_for(self, *, proof="none", decision="d"):
+        events = timeline.adapt_cth_comments(
+            [_cth_comment(1, created_at="2026-07-23T05:00:00Z", proof=proof, decision=decision)],
+            kind="issue",
+            number=637,
+        )
+        self.assertEqual(len(events), 1)
+        return events[0]
+
+    def test_assigned_secret_never_reaches_evidence_refs(self):
+        ev = self._refs_for(proof=f"authenticated with token={SYNTHETIC_SECRET_40_HEX}")
+        self.assertNotIn(SYNTHETIC_SECRET_40_HEX, ev.evidence_refs)
+        self.assertNotIn(SYNTHETIC_SECRET_40_HEX, json.dumps(ev.to_dict()))
+
+    def test_bare_secret_shaped_value_never_reaches_evidence_refs(self):
+        # An undeclared hex run in proof text is not evidence of anything, and
+        # proof itself is never serialized — so the value has no way out.
+        ev = self._refs_for(proof=f"proof {SYNTHETIC_SECRET_40_HEX}", decision="rotate the credential")
+        self.assertNotIn(SYNTHETIC_SECRET_40_HEX, ev.evidence_refs)
+        self.assertNotIn(SYNTHETIC_SECRET_40_HEX, json.dumps(ev.to_dict()))
+
+    def test_secret_absent_from_complete_serialized_payload(self):
+        import tempfile
+
+        comments = [
+            _cth_comment(
+                1,
+                created_at="2026-07-23T09:00:00Z",
+                proof=f"lease token={SYNTHETIC_SECRET_40_HEX} and bare {SYNTHETIC_SECRET_40_HEX}",
+                decision=f"rotate api_key={SYNTHETIC_SECRET_40_HEX}",
+            )
+        ]
+        with tempfile.TemporaryDirectory() as tmp:
+            db = os.path.join(tmp, "cp.sqlite3")
+            _seed_db(db)
+            snap = timeline.load_timeline(
+                remote="prgs", org="Scaled-Tech-Consulting", repo="Gitea-Tools",
+                issue=637, db_path=db, comment_source=lambda k, n: comments,
+            )
+            payload = json.dumps(snap.to_dict())
+            self.assertNotIn(SYNTHETIC_SECRET_40_HEX, payload)
+            # And the surface is clean by the redaction policy's own detectors.
+            from webui import console_redaction
+
+            self.assertEqual(console_redaction.scan_for_secrets(snap.to_dict()), [])
+
+    def test_legitimate_references_still_usable(self):
+        head = "4f3a464a1c455b6ecaaae9b6eef496c8f8ed451a"
+        ev = self._refs_for(
+            proof=f"closes #637, PR #849, commit abc1234, at head {head}",
+            decision="none",
+        )
+        for token in ("#637", "#849", "abc1234", head):
+            self.assertIn(token, ev.evidence_refs)
+
+    def test_undeclared_hex_words_are_not_references(self):
+        ev = self._refs_for(proof="the record was defaced and the facade decayed")
+        self.assertEqual(ev.evidence_refs, ())
+
+    def test_refs_revalidated_independently_before_serialization(self):
+        """Extraction is not trusted: the validator drops anything unproven."""
+        safe, dropped = timeline._validated_evidence_refs(
+            ["#637", "abc1234", "not-a-ref", f"token={SYNTHETIC_SECRET_40_HEX}", ""]
+        )
+        self.assertEqual(safe, ("#637", "abc1234"))
+        self.assertTrue(dropped)
+        self.assertNotIn(SYNTHETIC_SECRET_40_HEX, json.dumps(list(safe)))
+
+    def test_clean_event_is_not_marked_sensitive(self):
+        ev = self._refs_for(proof="closes #637")
+        self.assertEqual(ev.evidence_refs, ("#637",))
+        self.assertFalse(ev.sensitive)
+
+
+class TestTimelineApi(unittest.TestCase):
+    def setUp(self):
+        self._prev_db = os.environ.get(control_plane_db.DB_PATH_ENV)
+        self._prev_offline = os.environ.get("WEBUI_TEST_OFFLINE")
+        import tempfile
+
+        self._tmpdir = tempfile.TemporaryDirectory()
+        self._db = os.path.join(self._tmpdir.name, "cp.sqlite3")
+        _seed_db(self._db)
+        os.environ[control_plane_db.DB_PATH_ENV] = self._db
+        os.environ["WEBUI_TEST_OFFLINE"] = "1"
+        self.client = TestClient(create_app())
+
+    def tearDown(self):
+        if self._prev_db is None:
+            os.environ.pop(control_plane_db.DB_PATH_ENV, None)
+        else:
+            os.environ[control_plane_db.DB_PATH_ENV] = self._prev_db
+        if self._prev_offline is None:
+            os.environ.pop("WEBUI_TEST_OFFLINE", None)
+        else:
+            os.environ["WEBUI_TEST_OFFLINE"] = self._prev_offline
+        self._tmpdir.cleanup()
+
+    def test_api_returns_timeline(self):
+        resp = self.client.get("/api/v1/timeline")
+        self.assertEqual(resp.status_code, 200)
+        body = resp.json()
+        self.assertEqual(body["schema_version"], timeline.TIMELINE_SCHEMA_VERSION)
+        self.assertIn("events", body)
+        self.assertIn("pagination", body)
+        self.assertGreaterEqual(body["pagination"]["total"], 1)
+
+    def test_api_filter_by_issue(self):
+        resp = self.client.get("/api/v1/timeline?issue=637")
+        self.assertEqual(resp.status_code, 200)
+        events = resp.json()["events"]
+        self.assertTrue(events)
+        self.assertTrue(all(e["issue_number"] == 637 for e in events))
+
+    def test_api_pagination(self):
+        resp = self.client.get("/api/v1/timeline?limit=1&offset=0")
+        self.assertEqual(resp.status_code, 200)
+        pg = resp.json()["pagination"]
+        self.assertEqual(pg["limit"], 1)
+        self.assertEqual(len(resp.json()["events"]), 1)
+        if pg["total"] > 1:
+            self.assertTrue(pg["has_more"])
+
+    def test_api_is_read_only(self):
+        resp = self.client.post("/api/v1/timeline")
+        self.assertIn(resp.status_code, (404, 405))
+
+    def test_api_no_secret_leak(self):
+        resp = self.client.get("/api/v1/timeline?issue=637")
+        self.assertNotIn("ghs_ABCDEF1234567890abcdef", resp.text)
+
+    def test_api_refuses_unanswerable_session_filter(self):
+        """No handoff source is configured offline, so nothing can carry a session."""
+        resp = self.client.get("/api/v1/timeline?issue=637&session=sess-alpha")
+        self.assertEqual(resp.status_code, 422)
+        body = resp.json()
+        self.assertFalse(body["ok"])
+        self.assertEqual(body["error"]["code"], "filter_not_supported")
+        self.assertEqual(body["error"]["unsupported_filters"], ["session"])
+        self.assertEqual(body["events"], [])
+        self.assertEqual(body["pagination"]["total"], 0)
+
+    def test_api_unfiltered_read_stays_ok(self):
+        body = self.client.get("/api/v1/timeline?issue=637").json()
+        self.assertTrue(body["ok"])
+        self.assertIsNone(body["error"])
+
+
+if __name__ == "__main__":
+    unittest.main()

webui/app.py

@@ -45,6 +45,7 @@ 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,
@@ -410,6 +411,104 @@ 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 +548,7 @@ 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"]),

webui/timeline.py

@@ -0,0 +1,784 @@
+"""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,}$")
+
+
+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 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 = row.get("event_id")
+            event_type = (row.get("event_type") or "").strip()
+            if event_id is None or not event_type:
+                continue
+            kind = row.get("kind")
+            number = row.get("number")
+            issue_no, pr_no = _kind_to_numbers(kind, number)
+            sensitive = any(hint in 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 parse_cth_comment
+
+    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 "handoff"
+            comment_id = comment.get("id")
+            # 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}",
+                    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,
+                )
+            )
+        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,
+        reason=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,
+        reason=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": {"remote": self.remote, "org": self.org, "repo": self.repo},
+            "filters": self.filters,
+            "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()