feat(webui): read-only system-health API (Closes #634)

Adds `GET /api/v1/system/health`, a structured read-only health surface for
automated readiness checks, and keeps `/health` as the cheap liveness probe.

webui/system_health.py composes a DTO from fail-soft dependency probes: the
control-plane database, the local checkout, and — opt-in via `?deep=1` — live
Gitea reachability, each carrying status, reason, and probe latency. Required
probes drive readiness; the optional Gitea probe can only degrade overall
status, because local inventory stays serveable when the remote is
unreachable. A probe that did not run leaves readiness incomplete rather than
silently passing.

Read-only throughout: the control-plane database is opened through a `mode=ro`
URI because `ControlPlaneDB.__init__` creates directories and runs migrations,
which a health check must never do. No restart or reload control is exposed;
those are Phase 2 and #630 forbids process-kill recovery.

No unproven claims: `stale_runtime.mutation_safe` is true only when the
runtime, checkout, and remote commits are all known and equal, and MCP
namespaces always report `unproven` because a web process cannot exercise the
IDE-managed client path (#543). Probe details are redacted at the browser
boundary — URLs lose userinfo and query strings, credential-shaped text is
masked.

`/health` is expanded additively: every MVP key is retained, plus `started_at`,
`uptime_seconds`, and a pointer to the versioned API. The versioned route
returns 503 when not ready so automation can branch on the status code alone.

Verified at master 9eb0f29: focused file 40 passed / 11 subtests; `-k "webui or
health"` 230 passed / 159 subtests; full suite 4358 passed with the 11
pre-existing master-drift failures unchanged from the clean-master baseline.

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

docs/webui-local-dev.md

@@ -48,7 +48,8 @@ that govern when a write path may open (#632, epic #631).
 | Path | Description |
 |------|-------------|
 | `/` | Home / operator overview |
-| `/health` | JSON liveness (`status`, `service`, `mode`, `timestamp`) |
+| `/health` | JSON liveness (`status`, `service`, `mode`, `timestamp`, `uptime_seconds`) |
+| `/api/v1/system/health` | Structured read-only system health (#634) |
 | `/queue` | Live PR and issue queue dashboard (#429) |
 | `/api/queue` | JSON queue export with pagination metadata |
 | `/projects` | Project registry list (#427) |
@@ -72,6 +73,85 @@ Most routes are GET-only. POST/PUT/PATCH/DELETE return `405` with
 `read-only-mvp`, except `/audit` and `/api/audit` which accept POST for
 local validator preview only (no Gitea mutations, no server-side storage).
 
+## System health API (#634)
+
+`GET /api/v1/system/health` is the structured, read-only health surface for
+automated readiness checks. It is the first console API under the `/api/v1`
+prefix; the unversioned MVP exports remain as compatibility aliases.
+
+`/health` is unchanged for existing consumers — every MVP key is still present
+— and now also carries `started_at`, `uptime_seconds`, and a
+`system_health_api` pointer. It stays deliberately cheap and runs no dependency
+probe, because answering readiness costs real work.
+
+**Status codes.** `200` when ready, `503` when a required dependency failed or
+was never probed. Automation can branch on the code without parsing the body.
+
+**Query flags.** The Gitea check is a network call, so it is opt-in:
+`GET /api/v1/system/health?deep=1` runs it and caches the result for
+`WEBUI_HEALTH_PROBE_TTL_SECONDS` (default 15s) so dashboard polling does not
+amplify into remote load. Without the flag that probe reports `skipped`.
+
+**Dependencies.** `control_plane_db` and `repository` are required and drive
+readiness. `gitea` is optional: when it fails the overall `status` degrades but
+`readiness.ready` stays true, because local inventory is still serveable. Each
+entry carries `status`, `detail`, `required`, and `latency_ms`.
+
+Two honesty rules are worth knowing before reading the payload:
+
+* `stale_runtime.mutation_safe` is true only when the runtime, checkout, and
+  remote-tracking commits are all known and equal. An unfetched remote is
+  reported as indeterminate, never as safe.
+* `mcp_namespaces` entries are always `unproven`. A web process runs outside
+  the IDE-managed MCP client and cannot invoke a namespace tool, so per #543
+  only a `client_namespace` probe can prove that path.
+
+Sample response (abridged, healthy):
+
+```json
+{
+  "status": "ok",
+  "service": "mcp-control-plane-webui",
+  "mode": "read-only",
+  "api": "/api/v1/system/health",
+  "timestamp": "2026-07-22T11:04:18.512034+00:00",
+  "readiness": { "ready": true, "complete": true, "reasons": [] },
+  "version": {
+    "git_sha": "620ed6e9a9550b8da2ceb82d9ab8744e8920490f",
+    "git_describe": "v1.1.0-898-g620ed6e",
+    "control_plane_schema_version": 4,
+    "python_version": "3.14.5",
+    "known": true
+  },
+  "process": { "started_at": "2026-07-22T10:58:02.114+00:00", "uptime_seconds": 376.4 },
+  "deep_probes_requested": false,
+  "dependencies": [
+    {
+      "name": "control_plane_db",
+      "kind": "sqlite",
+      "status": "ok",
+      "detail": "schema v4 readable",
+      "required": true,
+      "healthy": true,
+      "latency_ms": 1.482,
+      "metadata": { "schema_version": 4, "active_leases": 3 }
+    },
+    { "name": "repository", "kind": "git", "status": "ok", "required": true, "healthy": true },
+    { "name": "gitea", "kind": "http", "status": "skipped", "required": false, "healthy": false }
+  ],
+  "mcp_namespaces": [
+    { "namespace": "gitea-author", "required_tool": "gitea_whoami", "status": "unproven" }
+  ],
+  "stale_runtime": { "stale": false, "determinable": true, "mutation_safe": true, "reasons": [] },
+  "probe_errors": []
+}
+```
+
+No restart, reload, or process-kill control is exposed here: those are Phase 2
+at the earliest, and #630 forbids process-kill recovery outright. Every probe
+opens its subject read-only — the control-plane database is opened through a
+`mode=ro` URI so a health check can never create or migrate a schema.
+
 ## Report audit (#431)
 
 Paste an LLM final report at `/audit` or POST JSON to `/api/audit`. The UI

gitea_mcp_server.py

@@ -12536,10 +12536,39 @@ def _try_auto_switch_for_operation(op: str, host: str | None = None) -> bool:
     return False
 
 
+def _git_default_remote_name(root: str) -> str:
+    """First configured git remote name for *root*, defaulting to 'origin'.
+
+    Used to resolve the live remote master target for parity (#610). Best
+    effort: any failure falls back to 'origin' so callers never raise.
+    """
+    try:
+        res = subprocess.run(
+            ["git", "-C", root, "remote"],
+            capture_output=True, text=True, check=False,
+        )
+    except Exception:
+        return "origin"
+    if res.returncode != 0:
+        return "origin"
+    names = [n.strip() for n in (res.stdout or "").splitlines() if n.strip()]
+    return names[0] if names else "origin"
+
+
 def _current_master_parity() -> dict:
-    """Assess this process's code against the on-disk master HEAD (#420)."""
+    """Assess this process's code against local and live remote master (#420/#610).
+
+    Compares the daemon's startup commit, the on-disk checkout HEAD, and the
+    live remote master target. A stale daemon relative to live master fails
+    closed for mutations even when the local checkout HEAD still matches the
+    startup commit. The live-remote read is best effort: an unresolved live
+    head leaves read-only diagnostics unblocked but is never mutation-safe.
+    """
     current_head = master_parity_gate.read_git_head(PROJECT_ROOT)
-    return master_parity_gate.assess_master_parity(_STARTUP_PARITY, current_head)
+    live_head = master_parity_gate.read_remote_master_head(
+        PROJECT_ROOT, remote=_git_default_remote_name(PROJECT_ROOT))
+    return master_parity_gate.assess_master_parity(
+        _STARTUP_PARITY, current_head, live_remote_head=live_head)
 
 
 def _current_runtime_mode_report(refresh: bool = False) -> dict:
@@ -16480,10 +16509,29 @@ def gitea_get_runtime_context(
         "restart_required": parity["restart_required"],
         "startup_head": parity["startup_head"],
         "current_head": parity["current_head"],
+        # #610 distinguished mutation-safety signals:
+        "daemon_start_head": parity["daemon_start_head"],
+        "local_head": parity["local_head"],
+        "live_remote_head": parity["live_remote_head"],
+        "live_known": parity["live_known"],
+        "live_stale": parity["live_stale"],
+        "mutation_safe": parity["mutation_safe"],
         "summary": master_parity_gate.format_parity(parity),
         "mutation_gate_enforced": not master_parity_gate.gate_disabled(),
+        # #610: the capability resolver is authoritative for mutation safety;
+        # local parity alone must never authorize a mutation.
+        "resolver_authoritative_for_mutation_safety": True,
     }
-    if parity["stale"] and not master_parity_gate.gate_disabled():
+    if parity["restart_required"] and not master_parity_gate.gate_disabled():
+        if parity["live_stale"]:
+            safe_next_action = (
+                "Daemon is stale relative to LIVE remote master "
+                f"(started {parity['startup_head'][:12] if parity['startup_head'] else 'unknown'}, "
+                f"live master {parity['live_remote_head'][:12] if parity['live_remote_head'] else 'unknown'}); "
+                "restart/reconnect the Gitea MCP server before mutating. The "
+                "capability resolver is authoritative for mutation safety."
+            )
+        else:
             safe_next_action = (
                 "Server code is stale relative to master; restart the Gitea MCP "
                 "server to load current capability gates before mutating. "
@@ -16537,6 +16585,13 @@ def gitea_assess_master_parity(
         "determinable": parity["determinable"],
         "startup_head": parity["startup_head"],
         "current_head": parity["current_head"],
+        # #610 distinguished mutation-safety signals:
+        "daemon_start_head": parity["daemon_start_head"],
+        "local_head": parity["local_head"],
+        "live_remote_head": parity["live_remote_head"],
+        "live_known": parity["live_known"],
+        "live_stale": parity["live_stale"],
+        "mutation_safe": parity["mutation_safe"],
         "mutation_gate_enforced": enforced,
         "summary": master_parity_gate.format_parity(parity),
         "reasons": parity["reasons"],
@@ -16553,7 +16608,7 @@ def gitea_assess_master_parity(
             source=canonical_source,
         ),
     }
-    if parity["stale"] and enforced:
+    if parity["restart_required"] and enforced:
         out["report"] = master_parity_gate.parity_report(parity)
     return out
 

master_parity_gate.py

@@ -24,12 +24,50 @@ from __future__ import annotations
 
 import os
 import subprocess
+import time
+
+# Live-remote head cache: the parity gate runs on every mutation and every
+# runtime-context read, so the ``git ls-remote`` result is cached briefly to
+# avoid a network round-trip per call (#610). Keyed by (root, remote, branch).
+_REMOTE_HEAD_CACHE: dict[tuple[str, str, str], tuple[float, str | None]] = {}
+_REMOTE_HEAD_TTL = 60.0
+
+# When True, ``read_remote_master_head`` never performs ``git ls-remote`` unless
+# ``GITEA_TEST_LIVE_REMOTE_HEAD`` is set. Conftest enables this suite-wide so
+# feature worktrees (whose HEAD differs from live master) cannot flip legacy
+# runtime-context assertions to live_stale, and so unit tests never depend on
+# a live network (PR #788 F1/F2 / issue #610). Module-level (not env-only) so
+# ``patch.dict(os.environ, …, clear=True)`` cannot re-enable the probe.
+_HERMETIC_TEST_MODE: bool = False
+
+
+def _clear_remote_head_cache() -> None:
+    """Reset the live-remote head cache (test isolation / forced refresh)."""
+    _REMOTE_HEAD_CACHE.clear()
+
+
+def set_hermetic_test_mode(enabled: bool) -> None:
+    """Enable or disable suite-wide hermetic live-remote reads (tests only)."""
+    global _HERMETIC_TEST_MODE
+    _HERMETIC_TEST_MODE = bool(enabled)
+    _clear_remote_head_cache()
+
+
+def hermetic_test_mode() -> bool:
+    """Return whether hermetic live-remote reads are active."""
+    return bool(_HERMETIC_TEST_MODE)
+
 
 # Environment escape hatches (ops + tests):
 #   GITEA_MCP_DISABLE_PARITY_GATE  -> disable enforcement entirely (fail open).
 #   GITEA_TEST_CURRENT_HEAD        -> force the "current" HEAD read, for tests.
 ENV_DISABLE = "GITEA_MCP_DISABLE_PARITY_GATE"
 ENV_TEST_CURRENT_HEAD = "GITEA_TEST_CURRENT_HEAD"
+# GITEA_TEST_LIVE_REMOTE_HEAD -> force the live remote master read, for tests.
+ENV_TEST_LIVE_REMOTE_HEAD = "GITEA_TEST_LIVE_REMOTE_HEAD"
+# GITEA_TEST_ALLOW_LIVE_REMOTE_PROBE -> opt a single test into a real ls-remote
+# even when hermetic mode is on (rare; prefer ENV_TEST_LIVE_REMOTE_HEAD).
+ENV_TEST_ALLOW_LIVE_REMOTE_PROBE = "GITEA_TEST_ALLOW_LIVE_REMOTE_PROBE"
 
 
 def read_git_head(root: str) -> str | None:
@@ -58,6 +96,75 @@ def read_git_head(root: str) -> str | None:
     return (res.stdout or "").strip() or None
 
 
+def read_remote_master_head(
+    root: str,
+    remote: str = "origin",
+    branch: str = "master",
+    ttl: float = _REMOTE_HEAD_TTL,
+) -> str | None:
+    """Return the live remote ``branch`` commit SHA, or ``None`` (#610).
+
+    Resolves the *live* target commit via ``git ls-remote`` so parity can tell
+    a daemon that is behind the live remote master apart from one whose local
+    checkout simply hasn't been pulled. ``None`` means the live head could not
+    be resolved (offline, no such remote, git unavailable, error) -- callers
+    must treat unknown live state as *not mutation-safe* while never blocking
+    read-only diagnostics. A ``GITEA_TEST_LIVE_REMOTE_HEAD`` override takes
+    precedence so the wiring can be exercised deterministically and offline.
+
+    The result is cached for *ttl* seconds per (root, remote, branch) so the
+    gate does not run a network probe on every mutation/read (``ttl=0`` forces
+    a live probe). Both hits and ``None`` misses are cached to bound offline
+    latency; the env override bypasses the cache and the subprocess entirely.
+
+    Under suite hermetic mode (``set_hermetic_test_mode(True)``, set by
+    conftest) a missing override returns ``None`` without network I/O so
+    feature-worktree test runs cannot observe live_stale against real master
+    (PR #788 F1) and unit tests stay offline (F2). Opt out with an explicit
+    ``GITEA_TEST_LIVE_REMOTE_HEAD`` pin or ``GITEA_TEST_ALLOW_LIVE_REMOTE_PROBE``.
+    """
+    forced = os.environ.get(ENV_TEST_LIVE_REMOTE_HEAD)
+    if forced is not None:
+        return forced.strip() or None
+    if _HERMETIC_TEST_MODE and not (
+        os.environ.get(ENV_TEST_ALLOW_LIVE_REMOTE_PROBE) or ""
+    ).strip():
+        # Hermetic default: live head unknown. live_stale stays False;
+        # mutation_safe is False when live is unknown (documented #610 note).
+        return None
+    # Defense in depth: even without the module flag, never probe while pytest
+    # is running unless the test opted into a real probe or set an override.
+    if (os.environ.get("PYTEST_CURRENT_TEST") or "").strip() and not (
+        os.environ.get(ENV_TEST_ALLOW_LIVE_REMOTE_PROBE) or ""
+    ).strip():
+        return None
+    if not root:
+        return None
+    key = (root, remote, branch)
+    now = time.monotonic()
+    if ttl > 0:
+        cached = _REMOTE_HEAD_CACHE.get(key)
+        if cached is not None and (now - cached[0]) < ttl:
+            return cached[1]
+    sha: str | None = None
+    try:
+        res = subprocess.run(
+            ["git", "-C", root, "ls-remote", remote, f"refs/heads/{branch}"],
+            capture_output=True,
+            text=True,
+            check=False,
+            timeout=5,
+        )
+        if res.returncode == 0:
+            lines = (res.stdout or "").strip().splitlines()
+            if lines:
+                sha = lines[0].split("\t", 1)[0].split()[0].strip() or None
+    except Exception:
+        sha = None
+    _REMOTE_HEAD_CACHE[key] = (now, sha)
+    return sha
+
+
 def capture_startup_parity(root: str, head: str | None = None) -> dict:
     """Capture the process source-tree baseline once at server startup.
 
@@ -72,18 +179,38 @@ def _short(sha: str | None) -> str:
     return sha[:12] if sha else "unknown"
 
 
-def assess_master_parity(startup: dict | None, current_head: str | None) -> dict:
+def assess_master_parity(
+    startup: dict | None,
+    current_head: str | None,
+    live_remote_head: str | None = None,
+) -> dict:
     """Compare the startup baseline against the current on-disk ``HEAD``.
 
-    Pure: both HEADs are supplied by the caller. Returns a structured result:
+    Pure: all HEADs are supplied by the caller. Returns a structured result:
 
     - ``in_parity``    -- server code matches the on-disk master (or parity
       could not be determined, which is not treated as stale).
     - ``stale``        -- the on-disk master has definitively advanced past the
       running process.
-    - ``restart_required`` -- alias of ``stale``; the recovery action.
+    - ``restart_required`` -- ``stale`` or ``live_stale``; the recovery action.
-    - ``determinable`` -- whether both HEADs were known well enough to compare.
+    - ``determinable`` -- whether both local HEADs were known well enough to
+      compare.
     - ``startup_head`` / ``current_head`` / ``reasons``.
+
+    #610 adds live-remote awareness so a daemon that is stale relative to the
+    *live* remote master cannot report a mutation-safe result even when the
+    local checkout HEAD still matches the daemon's startup commit:
+
+    - ``daemon_start_head`` -- the commit the running process started at
+      (alias of ``startup_head``, named for clarity in reports).
+    - ``local_head`` -- the on-disk checkout HEAD (alias of ``current_head``).
+    - ``live_remote_head`` -- the live remote target commit, or ``None`` when it
+      could not be fetched.
+    - ``live_known`` -- whether the live remote target was resolved.
+    - ``live_stale`` -- the live remote master has advanced past the running
+      process (daemon is behind live master) even if local parity is green.
+    - ``mutation_safe`` -- the daemon code, local checkout, and live remote
+      target all agree; the only state in which a mutation may rely on parity.
     """
     startup_head = (startup or {}).get("startup_head")
     reasons: list[str] = []
@@ -91,32 +218,56 @@ def assess_master_parity(startup: dict | None, current_head: str | None) -> dict
     if startup_head is None:
         reasons.append(
             "startup commit was not captured; code parity cannot be enforced")
-        return _result(True, False, False, startup_head, current_head, reasons)
+        return _result(True, False, False, startup_head, current_head,
+                       live_remote_head, False, reasons)
 
     if current_head is None:
         reasons.append(
             "current workspace HEAD could not be read; code parity cannot be "
             "enforced")
-        return _result(True, False, False, startup_head, current_head, reasons)
+        return _result(True, False, False, startup_head, current_head,
-
+                       live_remote_head, False, reasons)
-    if startup_head == current_head:
-        return _result(True, False, True, startup_head, current_head, reasons)
 
+    local_in_parity = startup_head == current_head
+    local_stale = not local_in_parity
+    if local_stale:
         reasons.append(
-        f"MCP server started at commit {_short(startup_head)} but the workspace "
+            f"MCP server started at commit {_short(startup_head)} but the "
-        f"master is now {_short(current_head)}; restart the server to load the "
+            f"workspace master is now {_short(current_head)}; restart the "
-        f"current capability gates")
+            f"server to load the current capability gates")
-    return _result(False, True, True, startup_head, current_head, reasons)
+
+    live_known = live_remote_head is not None
+    live_stale = live_known and live_remote_head != startup_head
+    if live_stale:
+        reasons.append(
+            f"live remote master is {_short(live_remote_head)} but the MCP "
+            f"server started at {_short(startup_head)}; the daemon is stale "
+            f"relative to live master -- restart/reconnect before mutating")
+
+    return _result(
+        local_in_parity, local_stale, True, startup_head, current_head,
+        live_remote_head, live_stale, reasons)
 
 
-def _result(in_parity, stale, determinable, startup_head, current_head, reasons):
+def _result(in_parity, stale, determinable, startup_head, current_head,
+            live_remote_head, live_stale, reasons):
+    live_known = live_remote_head is not None
+    mutation_safe = (
+        determinable and in_parity and live_known and not live_stale)
     return {
         "in_parity": in_parity,
         "stale": stale,
-        "restart_required": stale,
+        "restart_required": stale or live_stale,
         "determinable": determinable,
         "startup_head": startup_head,
         "current_head": current_head,
+        # #610 distinguished signals:
+        "daemon_start_head": startup_head,
+        "local_head": current_head,
+        "live_remote_head": live_remote_head,
+        "live_known": live_known,
+        "live_stale": live_stale,
+        "mutation_safe": mutation_safe,
         "reasons": list(reasons),
     }
 
@@ -130,11 +281,13 @@ def parity_block_reasons(assessment: dict) -> list[str]:
     """Block reasons for a mutation gate (empty when the mutation may proceed).
 
     A disabled gate or an in-parity / non-determinable assessment yields no
-    reasons; only a definitively stale server blocks.
+    reasons. A definitively stale server blocks, and (#610) a daemon that is
+    stale relative to the *live* remote master blocks even when the local
+    checkout HEAD still matches the daemon's startup commit.
     """
     if gate_disabled():
         return []
-    if assessment.get("stale"):
+    if assessment.get("stale") or assessment.get("live_stale"):
         return list(assessment.get("reasons") or
                     ["server code is stale relative to master (fail closed)"])
     return []
@@ -147,6 +300,10 @@ def parity_report(assessment: dict) -> dict:
         "restart_required": True,
         "startup_head": assessment.get("startup_head"),
         "current_head": assessment.get("current_head"),
+        # #610: name the live remote target so the report distinguishes a
+        # local-code stale from a daemon-behind-live-master stale.
+        "live_remote_head": assessment.get("live_remote_head"),
+        "live_stale": bool(assessment.get("live_stale")),
         "reasons": list(assessment.get("reasons") or []),
         "recovery": [
             "The running MCP server is executing code older than the current "
@@ -157,6 +314,45 @@ def parity_report(assessment: dict) -> dict:
     }
 
 
+def parity_resolver_disagreement(
+    assessment: dict,
+    resolver_restart_required: bool,
+) -> dict | None:
+    """Typed blocker when the resolver requires restart but parity looks green.
+
+    The capability resolver (``gitea_resolve_task_capability``) detects stale
+    runtime authoritatively for mutation safety (#610). When it requires a
+    restart, local-only parity must never override it: this returns a typed,
+    fail-closed blocker that names the resolver as authoritative. Returns
+    ``None`` when the resolver does not require a restart.
+    """
+    if not resolver_restart_required:
+        return None
+    parity_optimistic = bool(assessment.get("in_parity")) and not (
+        assessment.get("stale") or assessment.get("live_stale"))
+    return {
+        "kind": "parity_resolver_disagreement",
+        "restart_required": True,
+        "resolver_authoritative": True,
+        "parity_optimistic": parity_optimistic,
+        "daemon_start_head": assessment.get("daemon_start_head"),
+        "local_head": assessment.get("local_head"),
+        "live_remote_head": assessment.get("live_remote_head"),
+        "reasons": [
+            "The capability resolver requires a restart/reconnect (stale "
+            "runtime) but master-parity reported local code as in-parity. "
+            "The resolver is authoritative for mutation safety; do not mutate "
+            "on local parity alone. Restart/reconnect the Gitea MCP server "
+            "and re-verify before mutating.",
+        ],
+        "recovery": [
+            "Trust the resolver: treat this session as stale.",
+            "Restart or /mcp reconnect the Gitea MCP namespace so it reloads "
+            "current master and live target state, then re-run preflight.",
+        ],
+    }
+
+
 def format_parity(assessment: dict) -> str:
     """One-line human summary for logs / runtime context."""
     if assessment.get("stale"):

tests/conftest.py

@@ -167,6 +167,35 @@ def _reset_mutation_authority(monkeypatch):
 import pytest
 
 
+@pytest.fixture(autouse=True)
+def _hermetic_live_remote_master_head():
+    """#610 / PR #788 F1/F2: keep live-remote parity reads offline in tests.
+
+    ``read_remote_master_head`` would otherwise ``git ls-remote`` whenever
+    ``GITEA_TEST_LIVE_REMOTE_HEAD`` is unset. Feature worktrees under
+    ``branches/`` always differ from live master, so legacy suites that assert
+    runtime-context ``safe_next_action`` flip to live_stale. Module-level
+    hermetic mode survives ``patch.dict(os.environ, …, clear=True)``.
+    Tests that exercise the real probe path call
+    ``master_parity_gate.set_hermetic_test_mode(False)`` and/or set
+    ``GITEA_TEST_ALLOW_LIVE_REMOTE_PROBE``.
+    """
+    try:
+        import master_parity_gate as _mpg
+
+        _mpg.set_hermetic_test_mode(True)
+    except Exception:
+        _mpg = None
+    try:
+        yield
+    finally:
+        if _mpg is not None:
+            try:
+                _mpg.set_hermetic_test_mode(False)
+            except Exception:
+                pass
+
+
 @pytest.fixture(autouse=True)
 def _deterministic_workspace_remotes():
     try:

tests/test_master_parity_gate.py

@@ -78,6 +78,95 @@ class TestBlockReasonsAndReport(unittest.TestCase):
         self.assertTrue(report["recovery"])
 
 
+class TestLiveRemoteParity(unittest.TestCase):
+    """#610: parity must account for the live remote master, not just local.
+
+    The daemon can be stale relative to the live remote target while the local
+    checkout HEAD still matches the daemon's startup commit, so local parity
+    reports green even though a mutation would run against outdated code.
+    """
+
+    SHA_C = "c" * 40
+
+    def test_distinguishes_three_shas(self):
+        res = mp.assess_master_parity(
+            {"startup_head": SHA_A}, SHA_A, live_remote_head=SHA_B)
+        self.assertEqual(res["daemon_start_head"], SHA_A)
+        self.assertEqual(res["local_head"], SHA_A)
+        self.assertEqual(res["live_remote_head"], SHA_B)
+
+    def test_mutation_safe_only_when_all_three_match(self):
+        res = mp.assess_master_parity(
+            {"startup_head": SHA_A}, SHA_A, live_remote_head=SHA_A)
+        self.assertTrue(res["mutation_safe"])
+        self.assertTrue(res["live_known"])
+        self.assertFalse(res["live_stale"])
+
+    def test_live_stale_when_remote_advanced_past_daemon(self):
+        # Local checkout still matches the daemon start (local parity green),
+        # but the live remote master has advanced -> daemon is live-stale.
+        res = mp.assess_master_parity(
+            {"startup_head": SHA_A}, SHA_A, live_remote_head=SHA_B)
+        self.assertTrue(res["in_parity"])  # local parity still green
+        self.assertTrue(res["live_stale"])
+        self.assertFalse(res["mutation_safe"])
+        self.assertTrue(any("live" in r.lower() for r in res["reasons"]))
+
+    def test_live_unknown_is_not_mutation_safe_but_not_stale(self):
+        # Non-goal: unfetchable live remote must not be treated as stale for
+        # read-only, but a mutation-safe claim fails closed.
+        res = mp.assess_master_parity(
+            {"startup_head": SHA_A}, SHA_A, live_remote_head=None)
+        self.assertFalse(res["live_known"])
+        self.assertFalse(res["mutation_safe"])
+        self.assertFalse(res["live_stale"])
+        self.assertTrue(res["in_parity"])
+
+    def test_default_live_remote_preserves_legacy_shape(self):
+        # Callers that do not supply a live head keep the pre-#610 behavior:
+        # in-parity, not live-stale, no live-derived block.
+        res = mp.assess_master_parity({"startup_head": SHA_A}, SHA_A)
+        self.assertFalse(res["live_stale"])
+        self.assertEqual(mp.parity_block_reasons(res), [])
+
+
+class TestLiveStaleBlockAndReport(unittest.TestCase):
+    """#610: live-staleness must block mutations and surface a typed blocker."""
+
+    def test_live_stale_produces_block_reasons(self):
+        res = mp.assess_master_parity(
+            {"startup_head": SHA_A}, SHA_A, live_remote_head=SHA_B)
+        self.assertTrue(mp.parity_block_reasons(res))
+
+    def test_disable_env_suppresses_live_stale_block(self):
+        res = mp.assess_master_parity(
+            {"startup_head": SHA_A}, SHA_A, live_remote_head=SHA_B)
+        with patch.dict(os.environ, {mp.ENV_DISABLE: "1"}):
+            self.assertEqual(mp.parity_block_reasons(res), [])
+
+    def test_resolver_disagreement_returns_typed_blocker(self):
+        # Parity says local-green, resolver says restart required -> disagreement
+        # is a typed, fail-closed blocker naming the resolver as authoritative.
+        res = mp.assess_master_parity({"startup_head": SHA_A}, SHA_A)
+        blocker = mp.parity_resolver_disagreement(res, resolver_restart_required=True)
+        self.assertIsNotNone(blocker)
+        self.assertEqual(blocker["kind"], "parity_resolver_disagreement")
+        self.assertTrue(blocker["restart_required"])
+        self.assertTrue(blocker["resolver_authoritative"])
+
+    def test_no_disagreement_when_resolver_agrees(self):
+        res = mp.assess_master_parity({"startup_head": SHA_A}, SHA_A)
+        self.assertIsNone(
+            mp.parity_resolver_disagreement(res, resolver_restart_required=False))
+
+    def test_live_stale_report_names_live_remote(self):
+        res = mp.assess_master_parity(
+            {"startup_head": SHA_A}, SHA_A, live_remote_head=SHA_B)
+        report = mp.parity_report(res)
+        self.assertEqual(report["live_remote_head"], SHA_B)
+        self.assertTrue(report["restart_required"])
+
+
 class TestReadGitHead(unittest.TestCase):
     def test_test_override_takes_precedence(self):
         with patch.dict(os.environ, {mp.ENV_TEST_CURRENT_HEAD: SHA_B}):
@@ -95,6 +184,149 @@ class TestReadGitHead(unittest.TestCase):
             self.assertIsNone(mp.read_git_head(""))
 
 
+class TestReadRemoteMasterHead(unittest.TestCase):
+    """#610: live remote master head reader (env-overridable, fails to None)."""
+
+    def test_test_override_takes_precedence(self):
+        with patch.dict(os.environ, {mp.ENV_TEST_LIVE_REMOTE_HEAD: SHA_B}):
+            self.assertEqual(mp.read_remote_master_head("/nonexistent"), SHA_B)
+
+    def test_blank_override_is_none(self):
+        with patch.dict(os.environ, {mp.ENV_TEST_LIVE_REMOTE_HEAD: "   "}):
+            self.assertIsNone(mp.read_remote_master_head("/nonexistent"))
+
+    def test_unfetchable_remote_is_none(self):
+        # No override; a bogus root/remote must fail closed to None, never raise.
+        env = {k: v for k, v in os.environ.items()
+               if k != mp.ENV_TEST_LIVE_REMOTE_HEAD}
+        with patch.dict(os.environ, env, clear=True):
+            self.assertIsNone(
+                mp.read_remote_master_head("/nonexistent", remote="nope"))
+
+
+class TestRemoteHeadCache(unittest.TestCase):
+    """#610: live remote reads are cached with a TTL to stay off the network.
+
+    The parity gate runs on every mutation and every runtime-context read, so an
+    unbounded ``git ls-remote`` per call would be a latency/flakiness regression.
+    """
+
+    def setUp(self):
+        # These cases intentionally exercise the subprocess/cache path, so they
+        # opt out of suite-wide hermetic mode (PR #788 F1).
+        self._saved_hermetic = mp.hermetic_test_mode()
+        mp.set_hermetic_test_mode(False)
+        mp._clear_remote_head_cache()
+        env = {
+            k: v for k, v in os.environ.items()
+            if k not in (mp.ENV_TEST_LIVE_REMOTE_HEAD,
+                         mp.ENV_TEST_ALLOW_LIVE_REMOTE_PROBE,
+                         "PYTEST_CURRENT_TEST")
+        }
+        # Allow the probe path under hermetic defenses while still mocking
+        # subprocess so no real network call runs.
+        env[mp.ENV_TEST_ALLOW_LIVE_REMOTE_PROBE] = "1"
+        self._env = patch.dict(os.environ, env, clear=True)
+        self._env.start()
+        self.addCleanup(self._env.stop)
+        self.addCleanup(mp._clear_remote_head_cache)
+        self.addCleanup(
+            lambda: mp.set_hermetic_test_mode(self._saved_hermetic)
+        )
+
+    def _fake_run(self, sha):
+        class _R:
+            returncode = 0
+            stdout = f"{sha}\trefs/heads/master\n"
+        calls = {"n": 0}
+
+        def run(*args, **kwargs):
+            calls["n"] += 1
+            return _R()
+        return run, calls
+
+    def test_second_call_within_ttl_uses_cache(self):
+        run, calls = self._fake_run(SHA_B)
+        with patch.object(mp.subprocess, "run", run):
+            a = mp.read_remote_master_head("/repo", remote="prgs", ttl=100)
+            b = mp.read_remote_master_head("/repo", remote="prgs", ttl=100)
+        self.assertEqual(a, SHA_B)
+        self.assertEqual(b, SHA_B)
+        self.assertEqual(calls["n"], 1)
+
+    def test_zero_ttl_bypasses_cache(self):
+        run, calls = self._fake_run(SHA_B)
+        with patch.object(mp.subprocess, "run", run):
+            mp.read_remote_master_head("/repo", remote="prgs", ttl=0)
+            mp.read_remote_master_head("/repo", remote="prgs", ttl=0)
+        self.assertEqual(calls["n"], 2)
+
+    def test_env_override_never_touches_subprocess(self):
+        run, calls = self._fake_run(SHA_B)
+        with patch.dict(os.environ, {mp.ENV_TEST_LIVE_REMOTE_HEAD: SHA_A}):
+            with patch.object(mp.subprocess, "run", run):
+                self.assertEqual(
+                    mp.read_remote_master_head("/repo", remote="prgs"), SHA_A)
+        self.assertEqual(calls["n"], 0)
+
+
+class TestHermeticLiveRemoteReads(unittest.TestCase):
+    """#610 / PR #788 F1/F2: suite hermetic mode never hits the network."""
+
+    def setUp(self):
+        self._saved = mp.hermetic_test_mode()
+        mp.set_hermetic_test_mode(True)
+        mp._clear_remote_head_cache()
+        self.addCleanup(lambda: mp.set_hermetic_test_mode(self._saved))
+        self.addCleanup(mp._clear_remote_head_cache)
+
+    def test_hermetic_mode_returns_none_without_subprocess(self):
+        run_calls = {"n": 0}
+
+        def boom(*args, **kwargs):
+            run_calls["n"] += 1
+            raise AssertionError("ls-remote must not run under hermetic mode")
+
+        env = {
+            k: v for k, v in os.environ.items()
+            if k not in (mp.ENV_TEST_LIVE_REMOTE_HEAD,
+                         mp.ENV_TEST_ALLOW_LIVE_REMOTE_PROBE)
+        }
+        with patch.dict(os.environ, env, clear=True):
+            with patch.object(mp.subprocess, "run", boom):
+                self.assertIsNone(
+                    mp.read_remote_master_head("/repo", remote="prgs")
+                )
+        self.assertEqual(run_calls["n"], 0)
+
+    def test_hermetic_mode_survives_clear_true_env(self):
+        """Module flag, not env pin: clear=True cannot re-enable the probe."""
+        run_calls = {"n": 0}
+
+        def boom(*args, **kwargs):
+            run_calls["n"] += 1
+            raise AssertionError("ls-remote must not run after clear=True")
+
+        with patch.dict(os.environ, {}, clear=True):
+            with patch.object(mp.subprocess, "run", boom):
+                self.assertIsNone(mp.read_remote_master_head("/repo"))
+        self.assertEqual(run_calls["n"], 0)
+
+    def test_explicit_override_still_wins_under_hermetic(self):
+        run_calls = {"n": 0}
+
+        def boom(*args, **kwargs):
+            run_calls["n"] += 1
+            raise AssertionError("override must bypass subprocess")
+
+        with patch.dict(os.environ, {mp.ENV_TEST_LIVE_REMOTE_HEAD: SHA_B}):
+            with patch.object(mp.subprocess, "run", boom):
+                self.assertEqual(
+                    mp.read_remote_master_head("/repo"), SHA_B
+                )
+        self.assertEqual(run_calls["n"], 0)
+
+
 class TestServerWiring(unittest.TestCase):
     """Integration with the gate choke point in the server namespace."""
 
@@ -105,6 +337,13 @@ class TestServerWiring(unittest.TestCase):
         self._saved = self.srv._STARTUP_PARITY
         self.srv._STARTUP_PARITY = {"root": self.srv.PROJECT_ROOT,
                                     "startup_head": SHA_A}
+        # Keep the live-remote read hermetic (no real ls-remote network call):
+        # default the live master to the daemon start so parity is fully green
+        # unless a test overrides the live head explicitly (#610).
+        self._live_patch = patch.dict(
+            os.environ, {mp.ENV_TEST_LIVE_REMOTE_HEAD: SHA_A})
+        self._live_patch.start()
+        self.addCleanup(self._live_patch.stop)
 
     def tearDown(self):
         self.srv._STARTUP_PARITY = self._saved
@@ -147,6 +386,36 @@ class TestServerWiring(unittest.TestCase):
             self.assertTrue(out["in_parity"])
             self.assertNotIn("report", out)
 
+    # --- #610: live-remote wiring -------------------------------------------
+
+    def test_live_stale_blocks_mutation_though_local_green(self):
+        # Local checkout matches the daemon start (local parity green) but the
+        # live remote master has advanced -> mutations must fail closed.
+        with patch.dict(os.environ, {mp.ENV_TEST_CURRENT_HEAD: SHA_A,
+                                     mp.ENV_TEST_LIVE_REMOTE_HEAD: SHA_B}):
+            self.assertEqual(self.srv._master_parity_block("gitea.read"), [])
+            self.assertTrue(
+                self.srv._master_parity_block("gitea.pr.create"))
+
+    def test_assess_tool_exposes_three_distinct_shas(self):
+        with patch.dict(os.environ, {mp.ENV_TEST_CURRENT_HEAD: SHA_A,
+                                     mp.ENV_TEST_LIVE_REMOTE_HEAD: SHA_B}):
+            out = self.srv.gitea_assess_master_parity(remote="prgs")
+            self.assertEqual(out["daemon_start_head"], SHA_A)
+            self.assertEqual(out["local_head"], SHA_A)
+            self.assertEqual(out["live_remote_head"], SHA_B)
+            self.assertTrue(out["live_stale"])
+            self.assertFalse(out["mutation_safe"])
+            self.assertIn("report", out)
+
+    def test_assess_tool_mutation_safe_when_all_three_match(self):
+        with patch.dict(os.environ, {mp.ENV_TEST_CURRENT_HEAD: SHA_A,
+                                     mp.ENV_TEST_LIVE_REMOTE_HEAD: SHA_A}):
+            out = self.srv.gitea_assess_master_parity(remote="prgs")
+            self.assertTrue(out["mutation_safe"])
+            self.assertFalse(out["live_stale"])
+            self.assertNotIn("report", out)
+
 
 if __name__ == "__main__":
     unittest.main()

tests/test_webui_system_health.py

@@ -0,0 +1,499 @@
+"""Tests for the read-only system-health API (#634).
+
+Covers the acceptance criteria directly: a structured payload with readiness
+and a dependency list (AC1), version and uptime when knowable (AC2), stale
+runtime reported without a false mutation-safe claim (AC3), and the healthy /
+degraded-dependency / redaction cases (AC4).
+"""
+import json
+import os
+import sqlite3
+import sys
+import tempfile
+import unittest
+from pathlib import Path
+from unittest import mock
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
+
+from starlette.testclient import TestClient
+
+import control_plane_db
+from webui.app import create_app
+from webui.deployment_boundary import scan_text_for_client_secrets
+from webui.system_health import (
+    API_PATH,
+    STATUS_DEGRADED,
+    STATUS_DOWN,
+    STATUS_OK,
+    STATUS_SKIPPED,
+    DependencyProbe,
+    StaleRuntime,
+    assess_stale_runtime,
+    clear_probe_cache,
+    load_system_health,
+    namespace_summaries,
+    probe_control_plane_db,
+    probe_gitea,
+    process_uptime,
+    redact,
+    redact_url,
+    snapshot_to_dict,
+)
+
+
+def _probe(name, status, *, required=True, detail="detail", kind="test"):
+    return DependencyProbe(
+        name=name,
+        kind=kind,
+        status=status,
+        detail=detail,
+        required=required,
+        latency_ms=1.5,
+        metadata={},
+    )
+
+
+_ALL_HEALTHY = (
+    _probe("control_plane_db", STATUS_OK, kind="sqlite"),
+    _probe("repository", STATUS_OK, kind="git"),
+    _probe("gitea", STATUS_OK, required=False, kind="http"),
+)
+
+_CLEAN_PARITY = StaleRuntime(
+    daemon_head="abc123",
+    checkout_head="abc123",
+    remote_head="abc123",
+    stale=False,
+    determinable=True,
+    mutation_safe=True,
+    reasons=(),
+)
+
+
+class CleanParityMixin:
+    """Pin parity for tests about aggregation rather than staleness.
+
+    Without this the assertions depend on the real checkout: a worktree whose
+    branch is ahead of its upstream is genuinely stale, which would degrade the
+    overall status and make these cases fail for an unrelated reason.
+    """
+
+    def setUp(self):
+        super().setUp()
+        patcher = mock.patch(
+            "webui.system_health.assess_stale_runtime",
+            return_value=_CLEAN_PARITY,
+        )
+        patcher.start()
+        self.addCleanup(patcher.stop)
+
+
+class TestDependencyAggregation(CleanParityMixin, unittest.TestCase):
+    """AC1 — readiness and dependency list derived from probe results."""
+
+    def test_all_healthy_is_ok_and_ready(self):
+        snapshot = load_system_health(probes=_ALL_HEALTHY, daemon_head="abc123")
+        self.assertEqual(snapshot.status, STATUS_OK)
+        self.assertTrue(snapshot.ready)
+        self.assertTrue(snapshot.readiness_complete)
+        self.assertEqual(snapshot.readiness_reasons, ())
+        self.assertEqual(len(snapshot.dependencies), 3)
+
+    def test_required_dependency_down_blocks_readiness(self):
+        probes = (
+            _probe("control_plane_db", STATUS_DOWN, detail="file missing", kind="sqlite"),
+            _probe("repository", STATUS_OK, kind="git"),
+            _probe("gitea", STATUS_OK, required=False, kind="http"),
+        )
+        snapshot = load_system_health(probes=probes, daemon_head="abc123")
+        self.assertEqual(snapshot.status, STATUS_DOWN)
+        self.assertFalse(snapshot.ready)
+        self.assertTrue(
+            any("control_plane_db" in reason for reason in snapshot.readiness_reasons)
+        )
+
+    def test_optional_dependency_down_degrades_but_stays_ready(self):
+        """A failing optional probe must not claim the process itself is unready."""
+        probes = (
+            _probe("control_plane_db", STATUS_OK, kind="sqlite"),
+            _probe("repository", STATUS_OK, kind="git"),
+            _probe("gitea", STATUS_DOWN, required=False, detail="timeout", kind="http"),
+        )
+        snapshot = load_system_health(probes=probes, daemon_head="abc123")
+        self.assertEqual(snapshot.status, STATUS_DEGRADED)
+        self.assertTrue(snapshot.ready)
+        self.assertTrue(any("gitea" in reason for reason in snapshot.readiness_reasons))
+
+    def test_unrun_required_probe_leaves_readiness_incomplete(self):
+        """Not probed is not the same as passing."""
+        probes = (
+            _probe("control_plane_db", STATUS_OK, kind="sqlite"),
+            _probe("repository", STATUS_SKIPPED, detail="offline", kind="git"),
+        )
+        snapshot = load_system_health(probes=probes, daemon_head="abc123")
+        self.assertFalse(snapshot.ready)
+        self.assertFalse(snapshot.readiness_complete)
+        self.assertEqual(snapshot.status, STATUS_DEGRADED)
+
+    def test_skipped_optional_probe_does_not_block_readiness(self):
+        probes = (
+            _probe("control_plane_db", STATUS_OK, kind="sqlite"),
+            _probe("repository", STATUS_OK, kind="git"),
+            _probe("gitea", STATUS_SKIPPED, required=False, kind="http"),
+        )
+        snapshot = load_system_health(probes=probes, daemon_head="abc123")
+        self.assertTrue(snapshot.ready)
+        self.assertTrue(snapshot.readiness_complete)
+
+
+class TestVersionAndUptime(CleanParityMixin, unittest.TestCase):
+    """AC2 — version and uptime present when knowable."""
+
+    def test_uptime_and_start_time_present(self):
+        snapshot = load_system_health(probes=_ALL_HEALTHY, daemon_head="abc123")
+        self.assertGreaterEqual(snapshot.uptime_seconds, 0.0)
+        self.assertIn("T", snapshot.started_at)
+
+    def test_process_uptime_helper_matches_shape(self):
+        started_at, uptime = process_uptime()
+        self.assertIn("T", started_at)
+        self.assertGreaterEqual(uptime, 0.0)
+
+    def test_version_reports_python_and_schema_version(self):
+        probes = (
+            DependencyProbe(
+                name="control_plane_db",
+                kind="sqlite",
+                status=STATUS_OK,
+                detail="ok",
+                required=True,
+                latency_ms=1.0,
+                metadata={"schema_version": control_plane_db.SCHEMA_VERSION},
+            ),
+            _probe("repository", STATUS_OK, kind="git"),
+        )
+        snapshot = load_system_health(probes=probes, daemon_head="abc123")
+        self.assertEqual(
+            snapshot.version.control_plane_schema_version,
+            control_plane_db.SCHEMA_VERSION,
+        )
+        self.assertTrue(snapshot.version.python_version)
+
+    def test_version_known_flag_false_when_sha_unavailable(self):
+        with mock.patch("webui.system_health._git", return_value=None):
+            snapshot = load_system_health(probes=_ALL_HEALTHY, daemon_head="abc")
+        self.assertIsNone(snapshot.version.git_sha)
+        self.assertFalse(snapshot.version.known)
+
+
+class TestStaleRuntime(unittest.TestCase):
+    """AC3 — stale runtime reflected without a false mutation-safe claim."""
+
+    def test_matching_commits_are_mutation_safe(self):
+        assessment = assess_stale_runtime(
+            Path("/tmp"),
+            daemon_head="aaa",
+            git_reader=lambda *args: "aaa",
+        )
+        self.assertFalse(assessment.stale)
+        self.assertTrue(assessment.determinable)
+        self.assertTrue(assessment.mutation_safe)
+
+    def test_diverged_commits_are_stale_and_not_mutation_safe(self):
+        reads = {"HEAD": "aaa", "@{upstream}": "bbb"}
+        assessment = assess_stale_runtime(
+            Path("/tmp"),
+            daemon_head="aaa",
+            git_reader=lambda *args: reads.get(args[-1]),
+        )
+        self.assertTrue(assessment.stale)
+        self.assertFalse(assessment.mutation_safe)
+        self.assertTrue(assessment.reasons)
+
+    def test_unknown_remote_is_not_mutation_safe(self):
+        """Indeterminate must never read as safe."""
+        reads = {"HEAD": "aaa", "@{upstream}": None}
+        assessment = assess_stale_runtime(
+            Path("/tmp"),
+            daemon_head="aaa",
+            git_reader=lambda *args: reads.get(args[-1]),
+        )
+        self.assertFalse(assessment.determinable)
+        self.assertFalse(assessment.mutation_safe)
+        self.assertFalse(assessment.stale)
+        self.assertTrue(
+            any("indeterminate" in reason for reason in assessment.reasons)
+        )
+
+    def test_unobservable_daemon_head_is_disclosed(self):
+        assessment = assess_stale_runtime(
+            Path("/tmp"),
+            git_reader=lambda *args: "aaa",
+        )
+        self.assertTrue(
+            any("not observable" in reason for reason in assessment.reasons)
+        )
+
+    def test_stale_runtime_degrades_overall_status(self):
+        reads = {"HEAD": "aaa", "@{upstream}": "bbb"}
+        # Pinned rather than inherited: this path uses the default git reader,
+        # so the assertion must hold whether or not the suite runs offline.
+        with mock.patch.dict(os.environ, {"WEBUI_TEST_OFFLINE": ""}), mock.patch(
+            "webui.system_health._git",
+            side_effect=lambda repo, *args: reads.get(args[-1]),
+        ):
+            snapshot = load_system_health(probes=_ALL_HEALTHY, daemon_head="aaa")
+        self.assertTrue(snapshot.stale_runtime.stale)
+        self.assertFalse(snapshot.stale_runtime.mutation_safe)
+        self.assertEqual(snapshot.status, STATUS_DEGRADED)
+
+
+class TestControlPlaneDbProbe(unittest.TestCase):
+    """The required local dependency, probed read-only."""
+
+    def setUp(self):
+        self.tmp = tempfile.TemporaryDirectory()
+        self.addCleanup(self.tmp.cleanup)
+        self.db_path = str(Path(self.tmp.name) / "control-plane.db")
+
+    def _build_db(self, schema_version):
+        conn = sqlite3.connect(self.db_path)
+        conn.execute("CREATE TABLE schema_meta (key TEXT PRIMARY KEY, value TEXT)")
+        conn.execute("CREATE TABLE leases (lease_id TEXT PRIMARY KEY, status TEXT)")
+        conn.execute(
+            "INSERT INTO schema_meta(key, value) VALUES ('schema_version', ?)",
+            (str(schema_version),),
+        )
+        conn.execute("INSERT INTO leases(lease_id, status) VALUES ('l1', 'active')")
+        conn.commit()
+        conn.close()
+
+    def test_missing_database_is_down(self):
+        probe = probe_control_plane_db(str(Path(self.tmp.name) / "absent.db"))
+        self.assertEqual(probe.status, STATUS_DOWN)
+        self.assertTrue(probe.required)
+        self.assertIsNotNone(probe.latency_ms)
+
+    def test_matching_schema_is_ok(self):
+        self._build_db(control_plane_db.SCHEMA_VERSION)
+        probe = probe_control_plane_db(self.db_path)
+        self.assertEqual(probe.status, STATUS_OK)
+        self.assertEqual(
+            probe.metadata["schema_version"], control_plane_db.SCHEMA_VERSION
+        )
+        self.assertEqual(probe.metadata["active_leases"], 1)
+
+    def test_mismatched_schema_is_degraded(self):
+        self._build_db(control_plane_db.SCHEMA_VERSION + 99)
+        probe = probe_control_plane_db(self.db_path)
+        self.assertEqual(probe.status, STATUS_DEGRADED)
+
+    def test_probe_does_not_create_a_database(self):
+        """A health check must never initialise the substrate it inspects."""
+        absent = str(Path(self.tmp.name) / "never-created.db")
+        probe_control_plane_db(absent)
+        self.assertFalse(Path(absent).exists())
+
+    def test_unreadable_database_is_down_not_raised(self):
+        Path(self.db_path).write_text("this is not a sqlite database")
+        probe = probe_control_plane_db(self.db_path)
+        self.assertEqual(probe.status, STATUS_DOWN)
+
+
+class TestRedaction(unittest.TestCase):
+    """AC4 — redaction. No credential-shaped text crosses the boundary."""
+
+    def test_redacts_token_assignment(self):
+        cleaned = redact("failed with token=ghp_ABCDEFGHIJKLMNOPQRSTUVWXYZ012345")
+        self.assertNotIn("ghp_ABCDEFGHIJKLMNOPQRSTUVWXYZ012345", cleaned)
+        self.assertIn("[redacted]", cleaned)
+
+    def test_redacts_authorization_header_text(self):
+        cleaned = redact("Authorization: Bearer abcdefghijklmnopqrstuvwxyz123456")
+        self.assertNotIn("abcdefghijklmnopqrstuvwxyz123456", cleaned)
+
+    def test_redacts_long_opaque_strings(self):
+        cleaned = redact("value 0123456789abcdef0123456789abcdef here")
+        self.assertNotIn("0123456789abcdef0123456789abcdef", cleaned)
+
+    def test_url_userinfo_and_query_are_stripped(self):
+        cleaned = redact_url("https://user:[email protected]/api/v1?token=xyz")
+        self.assertNotIn("secretpass", cleaned)
+        self.assertNotIn("token=xyz", cleaned)
+        self.assertEqual(cleaned, "https://gitea.example.com/api/v1")
+
+    def test_url_inside_free_text_is_redacted(self):
+        cleaned = redact("GET https://u:[email protected]/x?token=abc failed")
+        self.assertNotIn("u:p@", cleaned)
+        self.assertNotIn("token=abc", cleaned)
+
+    def test_gitea_probe_failure_detail_is_redacted(self):
+        boom = RuntimeError(
+            "connection refused for https://user:[email protected]/api/v1/version"
+        )
+        with mock.patch("webui.system_health.get_auth_header", return_value="token x"), \
+                mock.patch("webui.system_health.api_request", side_effect=boom):
+            probe = probe_gitea("gitea.example.com")
+        self.assertEqual(probe.status, STATUS_DOWN)
+        self.assertNotIn("hunter2", probe.detail)
+        self.assertEqual(scan_text_for_client_secrets(probe.detail), [])
+
+    def test_credential_guard_refusal_is_a_status_not_a_crash(self):
+        with mock.patch(
+            "webui.system_health.get_auth_header",
+            side_effect=RuntimeError("daemon guard refused"),
+        ):
+            probe = probe_gitea("gitea.example.com")
+        self.assertEqual(probe.status, STATUS_DEGRADED)
+        self.assertFalse(probe.required)
+
+
+class TestNamespaceSummaries(unittest.TestCase):
+    """A web process cannot prove IDE namespace health, and must not claim to."""
+
+    def test_every_namespace_reports_unproven(self):
+        rows = namespace_summaries()
+        self.assertTrue(rows)
+        for row in rows:
+            with self.subTest(namespace=row["namespace"]):
+                self.assertEqual(row["status"], "unproven")
+                self.assertFalse(row["ide_namespace_proven"])
+                self.assertIn("client_namespace", row["reason"])
+
+
+class TestSystemHealthRoutes(CleanParityMixin, unittest.TestCase):
+    """The HTTP surface: versioned path, status codes, read-only guard."""
+
+    def setUp(self):
+        super().setUp()
+        clear_probe_cache()
+        self.addCleanup(clear_probe_cache)
+        self.client = TestClient(create_app())
+
+    def _patch_snapshot(self, probes, daemon_head="abc123"):
+        snapshot = load_system_health(probes=probes, daemon_head=daemon_head)
+        patcher = mock.patch(
+            "webui.app.load_system_health",
+            return_value=snapshot,
+        )
+        patcher.start()
+        self.addCleanup(patcher.stop)
+        return snapshot
+
+    def test_versioned_route_is_registered(self):
+        self.assertEqual(API_PATH, "/api/v1/system/health")
+        self._patch_snapshot(_ALL_HEALTHY)
+        response = self.client.get(API_PATH)
+        self.assertEqual(response.status_code, 200)
+
+    def test_healthy_payload_shape(self):
+        self._patch_snapshot(_ALL_HEALTHY)
+        data = self.client.get(API_PATH).json()
+        self.assertEqual(data["status"], STATUS_OK)
+        self.assertTrue(data["readiness"]["ready"])
+        self.assertTrue(data["readiness"]["complete"])
+        self.assertEqual(data["api"], API_PATH)
+        self.assertEqual(len(data["dependencies"]), 3)
+        for key in ("version", "process", "stale_runtime", "mcp_namespaces"):
+            self.assertIn(key, data)
+        self.assertIn("uptime_seconds", data["process"])
+        self.assertIn("mutation_safe", data["stale_runtime"])
+
+    def test_degraded_dependency_returns_503(self):
+        probes = (
+            _probe("control_plane_db", STATUS_DOWN, detail="missing", kind="sqlite"),
+            _probe("repository", STATUS_OK, kind="git"),
+        )
+        self._patch_snapshot(probes)
+        response = self.client.get(API_PATH)
+        self.assertEqual(response.status_code, 503)
+        data = response.json()
+        self.assertFalse(data["readiness"]["ready"])
+        self.assertTrue(data["readiness"]["reasons"])
+
+    def test_dependency_entries_expose_status_and_latency(self):
+        self._patch_snapshot(_ALL_HEALTHY)
+        data = self.client.get(API_PATH).json()
+        names = {entry["name"] for entry in data["dependencies"]}
+        self.assertEqual(names, {"control_plane_db", "repository", "gitea"})
+        for entry in data["dependencies"]:
+            with self.subTest(dependency=entry["name"]):
+                self.assertIn("status", entry)
+                self.assertIn("required", entry)
+                self.assertIn("latency_ms", entry)
+
+    def test_response_body_carries_no_client_secrets(self):
+        self._patch_snapshot(_ALL_HEALTHY)
+        body = self.client.get(API_PATH).text
+        self.assertEqual(scan_text_for_client_secrets(body), [])
+
+    def test_deep_flag_is_forwarded(self):
+        snapshot = load_system_health(probes=_ALL_HEALTHY, daemon_head="abc")
+        with mock.patch(
+            "webui.app.load_system_health", return_value=snapshot
+        ) as loader:
+            self.client.get(f"{API_PATH}?deep=1")
+            loader.assert_called_once_with(deep=True)
+
+    def test_shallow_is_the_default(self):
+        snapshot = load_system_health(probes=_ALL_HEALTHY, daemon_head="abc")
+        with mock.patch(
+            "webui.app.load_system_health", return_value=snapshot
+        ) as loader:
+            self.client.get(API_PATH)
+            loader.assert_called_once_with(deep=False)
+
+    def test_route_rejects_mutation_methods(self):
+        for method in ("POST", "PUT", "PATCH", "DELETE"):
+            with self.subTest(method=method):
+                response = self.client.request(method, API_PATH)
+                self.assertEqual(response.status_code, 405)
+                self.assertEqual(response.json()["error"], "read-only-mvp")
+
+    def test_default_shallow_call_skips_the_network_probe(self):
+        """The expensive probe must not run unless it was asked for."""
+        with mock.patch("webui.system_health.probe_gitea") as probe:
+            snapshot = load_system_health(deep=False)
+        probe.assert_not_called()
+        gitea = next(p for p in snapshot.dependencies if p.name == "gitea")
+        self.assertEqual(gitea.status, STATUS_SKIPPED)
+
+
+class TestHealthRouteBackwardCompatibility(unittest.TestCase):
+    """`/health` is expanded additively; MVP consumers must keep working."""
+
+    def setUp(self):
+        self.client = TestClient(create_app())
+
+    def test_mvp_keys_are_unchanged(self):
+        data = self.client.get("/health").json()
+        self.assertEqual(data["status"], "ok")
+        self.assertEqual(data["service"], "mcp-control-plane-webui")
+        self.assertEqual(data["mode"], "read-only-mvp")
+        self.assertIn("timestamp", data)
+        self.assertEqual(data["deployment"]["mode"], "internal-operator-console")
+
+    def test_health_points_at_the_versioned_api(self):
+        data = self.client.get("/health").json()
+        self.assertEqual(data["system_health_api"], API_PATH)
+        self.assertIn("uptime_seconds", data)
+        self.assertIn("started_at", data)
+
+    def test_health_runs_no_dependency_probe(self):
+        """Liveness must stay cheap: no probe, no snapshot assembly."""
+        with mock.patch("webui.app.load_system_health") as loader:
+            response = self.client.get("/health")
+        self.assertEqual(response.status_code, 200)
+        loader.assert_not_called()
+
+
+class TestSnapshotSerialisation(CleanParityMixin, unittest.TestCase):
+    def test_snapshot_dict_is_json_serialisable(self):
+        snapshot = load_system_health(probes=_ALL_HEALTHY, daemon_head="abc123")
+        encoded = json.dumps(snapshot_to_dict(snapshot))
+        self.assertIn("readiness", encoded)
+
+
+if __name__ == "__main__":
+    unittest.main()

tests/test_webui_worker_registry.py

@@ -0,0 +1,458 @@
+"""Tests for the worker registry and configuration schema (#798, epic #797)."""
+import json
+import sys
+import tempfile
+import unittest
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
+
+from webui.worker_registry import (
+    ALLOWED_ROLES,
+    SCHEMA_VERSION,
+    RegistryValidationError,
+    WorkerRegistry,
+    default_registry_path,
+    find_provider,
+    find_worker,
+    history_dir,
+    list_revisions,
+    load_registry,
+    registry_to_dict,
+    registry_to_document,
+    rollback_to_revision,
+    save_registry,
+    validate_payload,
+    worker_to_dict,
+    workers_for_provider,
+)
+
+_EXPECTED_PROVIDER_IDS = ("claude", "grok", "codex", "agy", "kimi-k")
+
+
+def _provider(provider_id: str = "claude", **overrides) -> dict:
+    payload = {
+        "id": provider_id,
+        "display_name": "Claude",
+        "vendor": "Anthropic",
+        "executable": "claude",
+        "available": True,
+        "models": ["claude-opus-4-8"],
+        "notes": "",
+    }
+    payload.update(overrides)
+    return payload
+
+
+def _worker(worker_id: str = "claude-author", **overrides) -> dict:
+    payload = {
+        "id": worker_id,
+        "display_name": "Claude author",
+        "provider": "claude",
+        "model": "claude-opus-4-8",
+        "project": "gitea-tools",
+        "role": "author",
+        "namespace": "gitea-author",
+        "profile": "prgs-author",
+        "workflow": "skills/llm-project-workflow/workflows/work-issue.md",
+        "schedule": {"kind": "cron", "expression": "0 * * * *"},
+        "timeout_seconds": 3600,
+        "enabled": True,
+        "scheduler": {"kind": "launchd", "label": "cc.prgs.claude.author"},
+        "notes": "",
+    }
+    payload.update(overrides)
+    return payload
+
+
+def _document(providers=None, workers=None, **overrides) -> dict:
+    payload = {
+        "version": SCHEMA_VERSION,
+        "revision": 1,
+        "updated_at": "2026-07-22T00:00:00Z",
+        "providers": providers if providers is not None else [_provider()],
+        "workers": workers if workers is not None else [_worker()],
+    }
+    payload.update(overrides)
+    return payload
+
+
+class _TempRegistryCase(unittest.TestCase):
+    """Base case giving each test an isolated registry file."""
+
+    def setUp(self):
+        self._tmp = tempfile.TemporaryDirectory()
+        self.addCleanup(self._tmp.cleanup)
+        self.path = Path(self._tmp.name) / "workers.registry.json"
+
+    def write(self, document: dict) -> Path:
+        self.path.write_text(json.dumps(document, indent=2) + "\n", encoding="utf-8")
+        return self.path
+
+    def parse(self, document: dict) -> WorkerRegistry:
+        return validate_payload(document, source_path=self.path)
+
+
+class TestPackagedRegistry(unittest.TestCase):
+    """AC: the declarative registry is the source of truth and ships with the app."""
+
+    def test_default_path_points_at_packaged_data(self):
+        path = default_registry_path()
+        self.assertEqual(path.name, "workers.registry.json")
+        self.assertEqual(path.parent.name, "data")
+
+    def test_packaged_registry_loads_and_validates(self):
+        registry = load_registry()
+        self.assertEqual(registry.version, SCHEMA_VERSION)
+        self.assertGreaterEqual(registry.revision, 1)
+
+    def test_packaged_registry_declares_all_five_providers(self):
+        registry = load_registry()
+        self.assertEqual(
+            tuple(provider.id for provider in registry.providers),
+            _EXPECTED_PROVIDER_IDS,
+        )
+
+    def test_packaged_registry_carries_no_credentials(self):
+        raw = default_registry_path().read_text(encoding="utf-8").lower()
+        for marker in ("token", "password", "secret", "api_key", "credential"):
+            self.assertNotIn(marker, raw)
+
+
+class TestSeparateEntities(_TempRegistryCase):
+    """AC: providers and configured workers are separate entities."""
+
+    def test_provider_may_exist_with_no_workers(self):
+        registry = self.parse(
+            _document(providers=[_provider("grok", display_name="Grok")], workers=[])
+        )
+        self.assertEqual(len(registry.providers), 1)
+        self.assertEqual(registry.workers, ())
+        self.assertEqual(workers_for_provider(registry, "grok"), ())
+
+    def test_many_workers_may_share_one_provider(self):
+        registry = self.parse(
+            _document(
+                workers=[
+                    _worker("claude-author"),
+                    _worker(
+                        "claude-reviewer",
+                        role="reviewer",
+                        namespace="gitea-reviewer",
+                        profile="prgs-reviewer",
+                        scheduler={"kind": "launchd", "label": "cc.prgs.claude.reviewer"},
+                    ),
+                ]
+            )
+        )
+        self.assertEqual(len(workers_for_provider(registry, "claude")), 2)
+        self.assertEqual(len(registry.providers), 1)
+
+    def test_worker_referencing_unknown_provider_is_refused(self):
+        with self.assertRaises(RegistryValidationError) as ctx:
+            self.parse(_document(workers=[_worker(provider="mystery")]))
+        self.assertIn("unknown provider", str(ctx.exception))
+
+    def test_lookup_helpers(self):
+        registry = self.parse(_document())
+        self.assertIsNotNone(find_worker(registry, "claude-author"))
+        self.assertIsNone(find_worker(registry, "absent"))
+        self.assertIsNotNone(find_provider(registry, "claude"))
+        self.assertIsNone(find_provider(registry, "absent"))
+
+
+class TestRecordedFields(_TempRegistryCase):
+    """AC: records provider, model, project, role, namespace/profile, workflow,
+    schedule, timeout, enabled state, and scheduler metadata."""
+
+    def test_every_required_field_is_recorded(self):
+        registry = self.parse(_document())
+        worker = registry.workers[0]
+        self.assertEqual(worker.provider, "claude")
+        self.assertEqual(worker.model, "claude-opus-4-8")
+        self.assertEqual(worker.project, "gitea-tools")
+        self.assertEqual(worker.role, "author")
+        self.assertEqual(worker.namespace, "gitea-author")
+        self.assertEqual(worker.profile, "prgs-author")
+        self.assertEqual(worker.workflow, "skills/llm-project-workflow/workflows/work-issue.md")
+        self.assertEqual(worker.schedule.kind, "cron")
+        self.assertEqual(worker.schedule.expression, "0 * * * *")
+        self.assertEqual(worker.timeout_seconds, 3600)
+        self.assertTrue(worker.enabled)
+        self.assertEqual(worker.scheduler.kind, "launchd")
+        self.assertEqual(worker.scheduler.label, "cc.prgs.claude.author")
+
+    def test_each_required_field_is_individually_required(self):
+        for field in (
+            "provider", "model", "project", "role", "namespace",
+            "profile", "workflow", "schedule", "timeout_seconds",
+            "enabled", "scheduler", "id", "display_name",
+        ):
+            with self.subTest(field=field):
+                worker = _worker()
+                worker.pop(field)
+                with self.assertRaises(RegistryValidationError):
+                    self.parse(_document(workers=[worker]))
+
+    def test_all_sanctioned_roles_are_accepted(self):
+        for role in ALLOWED_ROLES:
+            with self.subTest(role=role):
+                registry = self.parse(_document(workers=[_worker(role=role)]))
+                self.assertEqual(registry.workers[0].role, role)
+
+    def test_unsanctioned_role_is_refused(self):
+        with self.assertRaises(RegistryValidationError) as ctx:
+            self.parse(_document(workers=[_worker(role="admin")]))
+        self.assertIn("role must be one of", str(ctx.exception))
+
+    def test_worker_dict_round_trips_every_field(self):
+        registry = self.parse(_document())
+        encoded = worker_to_dict(registry.workers[0])
+        self.assertEqual(encoded, _worker())
+        json.dumps(encoded)  # must stay JSON-safe for the #799 API
+
+
+class TestSchemaValidation(_TempRegistryCase):
+    """AC: supports schema validation — and fails closed."""
+
+    def test_unsupported_version_is_refused(self):
+        with self.assertRaises(RegistryValidationError):
+            self.parse(_document(version=2))
+
+    def test_root_must_be_an_object(self):
+        with self.assertRaises(RegistryValidationError):
+            validate_payload([], source_path=self.path)
+
+    def test_providers_must_be_non_empty(self):
+        with self.assertRaises(RegistryValidationError):
+            self.parse(_document(providers=[]))
+
+    def test_unknown_top_level_field_is_refused(self):
+        with self.assertRaises(RegistryValidationError) as ctx:
+            self.parse(_document(fleet=[]))
+        self.assertIn("unknown fields", str(ctx.exception))
+
+    def test_unknown_worker_field_is_refused_not_ignored(self):
+        # A typo'd field must not be silently dropped: "timeout_second" would
+        # otherwise read as "no timeout declared".
+        worker = _worker()
+        worker["timeout_second"] = 30
+        with self.assertRaises(RegistryValidationError) as ctx:
+            self.parse(_document(workers=[worker]))
+        self.assertIn("timeout_second", str(ctx.exception))
+
+    def test_credentials_are_refused_anywhere_in_the_document(self):
+        for label, mutate in (
+            ("provider.api_token", lambda doc: doc["providers"][0].__setitem__("api_token", "x")),
+            ("worker.password", lambda doc: doc["workers"][0].__setitem__("password", "x")),
+            ("root.secret", lambda doc: doc.__setitem__("secret", "x")),
+        ):
+            with self.subTest(field=label):
+                document = _document()
+                mutate(document)
+                with self.assertRaises(ValueError) as ctx:
+                    self.parse(document)
+                self.assertIn("credential", str(ctx.exception).lower())
+
+    def test_duplicate_worker_id_is_refused(self):
+        workers = [_worker("dup"), _worker("dup", scheduler={"kind": "manual"})]
+        with self.assertRaises(RegistryValidationError) as ctx:
+            self.parse(_document(workers=workers))
+        self.assertIn("duplicate worker id", str(ctx.exception))
+
+    def test_duplicate_provider_id_is_refused(self):
+        with self.assertRaises(RegistryValidationError) as ctx:
+            self.parse(_document(providers=[_provider("claude"), _provider("claude")], workers=[]))
+        self.assertIn("duplicate provider id", str(ctx.exception))
+
+    def test_duplicate_launchagent_label_is_refused(self):
+        # Two workers sharing a label would silently overwrite each other's agent.
+        workers = [
+            _worker("a", scheduler={"kind": "launchd", "label": "cc.prgs.same"}),
+            _worker("b", scheduler={"kind": "launchd", "label": "cc.prgs.same"}),
+        ]
+        with self.assertRaises(RegistryValidationError) as ctx:
+            self.parse(_document(workers=workers))
+        self.assertIn("duplicate scheduler label", str(ctx.exception))
+
+    def test_manual_scheduler_needs_no_label_and_many_may_coexist(self):
+        workers = [
+            _worker("a", scheduler={"kind": "manual"}),
+            _worker("b", scheduler={"kind": "manual"}),
+        ]
+        registry = self.parse(_document(workers=workers))
+        self.assertEqual([w.scheduler.label for w in registry.workers], [None, None])
+
+    def test_launchd_scheduler_requires_a_label(self):
+        with self.assertRaises(RegistryValidationError) as ctx:
+            self.parse(_document(workers=[_worker(scheduler={"kind": "launchd"})]))
+        self.assertIn("label is required", str(ctx.exception))
+
+    def test_unknown_scheduler_kind_is_refused(self):
+        with self.assertRaises(RegistryValidationError):
+            self.parse(_document(workers=[_worker(scheduler={"kind": "systemd", "label": "x"})]))
+
+    def test_timeout_must_be_a_positive_bounded_integer(self):
+        for bad in (0, -1, "3600", 1.5, True, 86_401):
+            with self.subTest(timeout=bad):
+                with self.assertRaises(RegistryValidationError):
+                    self.parse(_document(workers=[_worker(timeout_seconds=bad)]))
+
+    def test_enabled_must_be_a_real_boolean(self):
+        for bad in ("true", 1, None):
+            with self.subTest(enabled=bad):
+                with self.assertRaises(RegistryValidationError):
+                    self.parse(_document(workers=[_worker(enabled=bad)]))
+
+    def test_identifier_shape_is_enforced(self):
+        for bad in ("Claude Author", "-leading", "UPPER", ""):
+            with self.subTest(worker_id=bad):
+                with self.assertRaises(RegistryValidationError):
+                    self.parse(_document(workers=[_worker(bad)]))
+
+
+class TestScheduleValidation(_TempRegistryCase):
+    """Schedules are declarations; next-run computation belongs to #803."""
+
+    def test_interval_schedule_requires_positive_seconds(self):
+        registry = self.parse(
+            _document(workers=[_worker(schedule={"kind": "interval", "seconds": 900})])
+        )
+        self.assertEqual(registry.workers[0].schedule.seconds, 900)
+        with self.assertRaises(RegistryValidationError):
+            self.parse(_document(workers=[_worker(schedule={"kind": "interval"})]))
+        with self.assertRaises(RegistryValidationError):
+            self.parse(_document(workers=[_worker(schedule={"kind": "interval", "seconds": 0})]))
+
+    def test_cron_schedule_requires_five_fields(self):
+        with self.assertRaises(RegistryValidationError) as ctx:
+            self.parse(_document(workers=[_worker(schedule={"kind": "cron", "expression": "0 *"})]))
+        self.assertIn("five crontab fields", str(ctx.exception))
+
+    def test_manual_schedule_needs_no_timing(self):
+        registry = self.parse(_document(workers=[_worker(schedule={"kind": "manual"})]))
+        schedule = registry.workers[0].schedule
+        self.assertEqual(schedule.kind, "manual")
+        self.assertIsNone(schedule.seconds)
+        self.assertIsNone(schedule.expression)
+
+    def test_fields_from_the_wrong_kind_are_refused(self):
+        with self.assertRaises(RegistryValidationError) as ctx:
+            self.parse(_document(workers=[_worker(schedule={"kind": "manual", "seconds": 60})]))
+        self.assertIn("not valid for kind", str(ctx.exception))
+
+    def test_unknown_schedule_kind_is_refused(self):
+        with self.assertRaises(RegistryValidationError):
+            self.parse(_document(workers=[_worker(schedule={"kind": "hourly"})]))
+
+
+class TestAtomicPersistence(_TempRegistryCase):
+    """AC: atomic persistence."""
+
+    def test_save_then_load_round_trips(self):
+        registry = self.parse(_document())
+        save_registry(registry, self.path)
+        reloaded = load_registry(self.path)
+        self.assertEqual(
+            [worker_to_dict(w) for w in reloaded.workers],
+            [worker_to_dict(w) for w in registry.workers],
+        )
+
+    def test_save_leaves_no_temp_files_behind(self):
+        registry = self.parse(_document())
+        save_registry(registry, self.path)
+        save_registry(registry, self.path)
+        leftovers = [p.name for p in self.path.parent.iterdir() if p.name.startswith(".")]
+        self.assertEqual(leftovers, [])
+
+    def test_save_refuses_to_persist_an_invalid_document(self):
+        registry = self.parse(_document())
+        broken = WorkerRegistry(
+            version=registry.version,
+            revision=registry.revision,
+            updated_at=registry.updated_at,
+            providers=registry.providers,
+            # A worker whose provider is not declared in the registry.
+            workers=tuple(
+                type(worker)(**{**worker.__dict__, "provider": "vanished"})
+                for worker in registry.workers
+            ),
+            source_path=self.path,
+        )
+        with self.assertRaises(RegistryValidationError):
+            save_registry(broken, self.path)
+        self.assertFalse(self.path.exists(), "invalid save must not create the file")
+
+    def test_document_shape_excludes_local_paths_but_api_shape_includes_it(self):
+        registry = self.parse(_document())
+        self.assertNotIn("source_path", registry_to_document(registry))
+        self.assertEqual(registry_to_dict(registry)["source_path"], str(self.path))
+
+
+class TestVersioningAndRollback(_TempRegistryCase):
+    """AC: versioning and rollback."""
+
+    def _seed(self) -> WorkerRegistry:
+        self.write(_document())
+        return load_registry(self.path)
+
+    def test_revision_increments_on_each_save(self):
+        registry = self._seed()
+        self.assertEqual(registry.revision, 1)
+        second = save_registry(registry, self.path)
+        self.assertEqual(second.revision, 2)
+        third = save_registry(second, self.path)
+        self.assertEqual(third.revision, 3)
+
+    def test_updated_at_is_refreshed_and_utc(self):
+        registry = self._seed()
+        saved = save_registry(registry, self.path)
+        self.assertRegex(saved.updated_at, r"^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}Z$")
+
+    def test_superseded_revisions_are_retained(self):
+        registry = self._seed()
+        second = save_registry(registry, self.path)
+        save_registry(second, self.path)
+        self.assertEqual(list_revisions(self.path), (1, 2))
+        self.assertTrue(history_dir(self.path).is_dir())
+
+    def test_rollback_restores_prior_content_as_a_new_revision(self):
+        self.write(_document(workers=[_worker("original")]))
+        registry = load_registry(self.path)
+
+        changed = WorkerRegistry(
+            version=registry.version,
+            revision=registry.revision,
+            updated_at=registry.updated_at,
+            providers=registry.providers,
+            workers=(),  # operator deletes every worker
+            source_path=self.path,
+        )
+        save_registry(changed, self.path)
+        self.assertEqual(load_registry(self.path).workers, ())
+
+        restored = rollback_to_revision(1, self.path)
+        self.assertEqual([w.id for w in restored.workers], ["original"])
+        # Append-only: the rollback publishes a new head rather than rewinding.
+        self.assertGreater(restored.revision, 2)
+        self.assertEqual([w.id for w in load_registry(self.path).workers], ["original"])
+
+    def test_rollback_to_unknown_revision_fails_closed(self):
+        self._seed()
+        with self.assertRaises(RegistryValidationError) as ctx:
+            rollback_to_revision(99, self.path)
+        self.assertIn("not retained", str(ctx.exception))
+
+    def test_revision_must_be_a_positive_integer(self):
+        for bad in (0, -1, "1", None):
+            with self.subTest(revision=bad):
+                with self.assertRaises(RegistryValidationError):
+                    self.parse(_document(revision=bad))
+
+    def test_history_is_empty_before_any_save(self):
+        self.write(_document())
+        self.assertEqual(list_revisions(self.path), ())
+
+
+if __name__ == "__main__":
+    unittest.main()

webui/app.py

@@ -29,6 +29,12 @@ 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.system_health import (
+    API_PATH as SYSTEM_HEALTH_API_PATH,
+    load_system_health,
+    process_uptime,
+    snapshot_to_dict as system_health_to_dict,
+)
 
 _READ_ONLY_METHODS = frozenset({"GET", "HEAD", "OPTIONS"})
 _AUDIT_MUTATION_PATHS = frozenset({"/audit", "/api/audit"})
@@ -62,16 +68,43 @@ async def home(_request: Request) -> HTMLResponse:
 
 
 async def health(_request: Request) -> JSONResponse:
+    """Liveness only — deliberately cheap, runs no dependency probe (#634).
+
+    Every MVP key is retained so existing pollers keep working; the additions
+    are a pointer to the structured API and the in-memory process uptime.
+    Readiness lives at that API because answering it costs real probes.
+    """
     bind_host = _request.app.state.webui_bind_host
+    started_at, uptime_seconds = process_uptime()
     return JSONResponse({
         "status": "ok",
         "service": "mcp-control-plane-webui",
         "mode": "read-only-mvp",
         "timestamp": datetime.now(timezone.utc).isoformat(),
         "deployment": deployment_snapshot(bind_host=bind_host),
+        "started_at": started_at,
+        "uptime_seconds": uptime_seconds,
+        "system_health_api": SYSTEM_HEALTH_API_PATH,
     })
 
 
+def _truthy_flag(value: str | None) -> bool:
+    return (value or "").strip().lower() in {"1", "true", "yes", "on"}
+
+
+async def api_system_health(request: Request) -> JSONResponse:
+    """Structured read-only system health (#634).
+
+    `?deep=1` opts into the expensive network probe. The response status code
+    reflects readiness so automated checks can branch on it without parsing the
+    body: 200 when ready, 503 when a required dependency failed or never ran.
+    """
+    deep = _truthy_flag(request.query_params.get("deep"))
+    snapshot = load_system_health(deep=deep)
+    payload = system_health_to_dict(snapshot)
+    return JSONResponse(payload, status_code=200 if snapshot.ready else 503)
+
+
 async def queue(_request: Request) -> HTMLResponse:
     snapshot = load_queue_snapshot()
     return HTMLResponse(render_page(title="Queue", body_html=render_queue_page(snapshot)))
@@ -263,6 +296,7 @@ def create_app(*, bind_host: str | None = None) -> Starlette:
         routes=[
             Route("/", home, methods=["GET"]),
             Route("/health", health, methods=["GET"]),
+            Route(SYSTEM_HEALTH_API_PATH, api_system_health, methods=["GET"]),
             Route("/queue", queue, methods=["GET"]),
             Route("/api/queue", api_queue, methods=["GET"]),
             Route("/projects", projects, methods=["GET"]),

webui/data/workers.registry.json

@@ -0,0 +1,57 @@
+{
+  "version": 1,
+  "revision": 1,
+  "updated_at": "2026-07-22T00:00:00Z",
+  "providers": [
+    {
+      "id": "claude",
+      "display_name": "Claude",
+      "vendor": "Anthropic",
+      "executable": "claude",
+      "available": true,
+      "models": [
+        "claude-opus-4-8",
+        "claude-sonnet-5",
+        "claude-haiku-4-5-20251001"
+      ],
+      "notes": "Model list is a declaration. Live enumeration and version inspection belong to the provider adapter framework (#800)."
+    },
+    {
+      "id": "grok",
+      "display_name": "Grok",
+      "vendor": "xAI",
+      "executable": "grok",
+      "available": true,
+      "models": [],
+      "notes": "Models enumerated by the provider adapter (#800); not declared here."
+    },
+    {
+      "id": "codex",
+      "display_name": "Codex",
+      "vendor": "OpenAI",
+      "executable": "codex",
+      "available": true,
+      "models": [],
+      "notes": "Models enumerated by the provider adapter (#800); not declared here."
+    },
+    {
+      "id": "agy",
+      "display_name": "AGY",
+      "vendor": "Antigravity",
+      "executable": "agy",
+      "available": true,
+      "models": [],
+      "notes": "MCP allowlist gating applies to this provider; confirm server-side allowlist before configuring a worker."
+    },
+    {
+      "id": "kimi-k",
+      "display_name": "Kimi K",
+      "vendor": "Moonshot AI",
+      "executable": "kimi",
+      "available": true,
+      "models": [],
+      "notes": "Provider id is kimi-k; the executable on PATH is kimi. Models enumerated by the provider adapter (#800)."
+    }
+  ],
+  "workers": []
+}

webui/project_registry.py

@@ -8,27 +8,7 @@ from dataclasses import dataclass
 from pathlib import Path
 from typing import Any
 
-_FORBIDDEN_EXACT_KEYS = frozenset({
+from webui.registry_safety import reject_credential_keys as _reject_credential_keys
-    "token",
-    "password",
-    "secret",
-    "credential",
-    "auth",
-    "api_key",
-    "api-key",
-})
-_FORBIDDEN_KEY_PREFIXES = ("auth_", "api_key_", "api-key_")
-_FORBIDDEN_KEY_SUFFIXES = ("_token", "_secret", "_password", "_credential", "_auth")
-
-
-def _is_forbidden_key(key: str) -> bool:
-    lowered = key.lower()
-    if lowered in _FORBIDDEN_EXACT_KEYS:
-        return True
-    return (
-        lowered.startswith(_FORBIDDEN_KEY_PREFIXES)
-        or lowered.endswith(_FORBIDDEN_KEY_SUFFIXES)
-    )
 
 _REQUIRED_PROJECT_FIELDS = (
     "id",
@@ -79,18 +59,6 @@ def default_registry_path() -> Path:
     return (Path(__file__).resolve().parent / "data" / "projects.registry.json").resolve()
 
 
-def _reject_credential_keys(obj: Any, *, path: str = "") -> None:
-    if isinstance(obj, dict):
-        for key, value in obj.items():
-            key_path = f"{path}.{key}" if path else key
-            if _is_forbidden_key(key):
-                raise ValueError(f"registry must not store credentials ({key_path})")
-            _reject_credential_keys(value, path=key_path)
-    elif isinstance(obj, list):
-        for index, item in enumerate(obj):
-            _reject_credential_keys(item, path=f"{path}[{index}]")
-
-
 def _parse_onboarding(raw: list[dict[str, Any]] | None) -> tuple[OnboardingStep, ...]:
     if not raw:
         return ()

webui/registry_safety.py

@@ -0,0 +1,52 @@
+"""Shared credential-rejection guard for web UI registries (#427, #798).
+
+Registries are operator-editable declarative files that the web UI loads and,
+for the worker registry, writes back. None of them may ever carry a secret:
+credentials belong in the keychain and reach worker processes through
+environment injection, never through a file the browser layer can read.
+
+The check is structural rather than value-based on purpose. A value scanner has
+to guess what a secret looks like; a key scanner refuses the *shape* of a
+credential field, so an operator cannot introduce one by accident and a later
+loader cannot silently pass one through.
+"""
+
+from __future__ import annotations
+
+from typing import Any
+
+_FORBIDDEN_EXACT_KEYS = frozenset({
+    "token",
+    "password",
+    "secret",
+    "credential",
+    "auth",
+    "api_key",
+    "api-key",
+})
+_FORBIDDEN_KEY_PREFIXES = ("auth_", "api_key_", "api-key_")
+_FORBIDDEN_KEY_SUFFIXES = ("_token", "_secret", "_password", "_credential", "_auth")
+
+
+def is_forbidden_key(key: str) -> bool:
+    """Return True when *key* names a credential field."""
+    lowered = key.lower()
+    if lowered in _FORBIDDEN_EXACT_KEYS:
+        return True
+    return (
+        lowered.startswith(_FORBIDDEN_KEY_PREFIXES)
+        or lowered.endswith(_FORBIDDEN_KEY_SUFFIXES)
+    )
+
+
+def reject_credential_keys(obj: Any, *, path: str = "", subject: str = "registry") -> None:
+    """Raise ValueError when *obj* carries a credential-shaped key at any depth."""
+    if isinstance(obj, dict):
+        for key, value in obj.items():
+            key_path = f"{path}.{key}" if path else key
+            if is_forbidden_key(key):
+                raise ValueError(f"{subject} must not store credentials ({key_path})")
+            reject_credential_keys(value, path=key_path, subject=subject)
+    elif isinstance(obj, list):
+        for index, item in enumerate(obj):
+            reject_credential_keys(item, path=f"{path}[{index}]", subject=subject)

webui/system_health.py

@@ -0,0 +1,682 @@
+"""Read-only system-health model for the operator console API (#634).
+
+`/health` answers liveness only. Operators automating readiness checks need a
+structured view of *why* the control plane is or is not usable: which
+dependencies answered, how long they took, what version of the code is running,
+and whether the runtime is stale relative to its remote.
+
+Three rules shape this module.
+
+* **Read-only.** Every probe opens its subject read-only. The control-plane
+  database is opened through a ``mode=ro`` URI so a health check can never
+  create or migrate a schema, and no probe writes, restarts, or reloads
+  anything — restart controls are Phase 2, and #630 forbids process-kill
+  recovery outright.
+* **Fail-soft.** A dependency that is unreachable is a *status*, not an
+  exception. Probes catch their own failures and report them as a degraded or
+  down entry carrying a reason.
+* **Never claim more than was proven.** Readiness is derived only from probes
+  that actually ran, ``mutation_safe`` stays false unless the parity commits are
+  known and equal, and an MCP namespace is reported unproven because a web
+  process cannot exercise the IDE-managed client path (#543).
+"""
+
+from __future__ import annotations
+
+import os
+import re
+import sqlite3
+import subprocess
+import time
+from dataclasses import dataclass
+from datetime import datetime, timezone
+from pathlib import Path
+from typing import Any, Callable
+from urllib.parse import urlsplit, urlunsplit
+
+import control_plane_db
+import mcp_namespace_health
+from gitea_auth import api_request, get_auth_header, gitea_url
+
+from webui.project_registry import load_registry
+
+SERVICE_NAME = "mcp-control-plane-webui"
+API_PATH = "/api/v1/system/health"
+
+STATUS_OK = "ok"
+STATUS_DEGRADED = "degraded"
+STATUS_DOWN = "down"
+STATUS_SKIPPED = "skipped"
+STATUS_UNPROVEN = "unproven"
+
+# Statuses that count as a healthy answer from a probe.
+_HEALTHY_STATUSES = frozenset({STATUS_OK})
+# Statuses meaning "this probe did not run", as opposed to "it ran and failed".
+_NOT_RUN_STATUSES = frozenset({STATUS_SKIPPED})
+
+_DEEP_PROBE_TTL_ENV = "WEBUI_HEALTH_PROBE_TTL_SECONDS"
+_DEFAULT_DEEP_PROBE_TTL = 15.0
+_GITEA_PROBE_TIMEOUT_SECONDS = 5.0
+
+_OFFLINE_ENV = "WEBUI_TEST_OFFLINE"
+
+# Credential-shaped material that must never reach the browser, mirroring the
+# forbidden client patterns in webui/deployment_boundary.py.
+_SECRET_RE = re.compile(
+    r"(?i)\b(token|password|passwd|secret|authorization|bearer)\b\s*[:=]?\s*\S+"
+)
+_LONG_OPAQUE_RE = re.compile(r"\b[A-Za-z0-9_\-]{32,}\b")
+
+# Captured once at import so uptime measures this process, not the request.
+_STARTED_AT = datetime.now(timezone.utc)
+_STARTED_MONOTONIC = time.monotonic()
+
+# TTL cache for the expensive (network) probe only.
+_deep_cache: dict[str, tuple[float, "DependencyProbe"]] = {}
+
+
+@dataclass(frozen=True)
+class DependencyProbe:
+    """One dependency check, fail-soft, with its own latency."""
+
+    name: str
+    kind: str
+    status: str
+    detail: str
+    required: bool
+    latency_ms: float | None = None
+    metadata: dict[str, Any] | None = None
+
+    @property
+    def healthy(self) -> bool:
+        return self.status in _HEALTHY_STATUSES
+
+    @property
+    def ran(self) -> bool:
+        return self.status not in _NOT_RUN_STATUSES
+
+
+@dataclass(frozen=True)
+class VersionInfo:
+    git_sha: str | None
+    git_describe: str | None
+    control_plane_schema_version: int | None
+    python_version: str
+    known: bool
+
+
+@dataclass(frozen=True)
+class StaleRuntime:
+    """Parity between the running code, the checkout, and the remote.
+
+    ``mutation_safe`` is deliberately conservative: unknown is not safe.
+    """
+
+    daemon_head: str | None
+    checkout_head: str | None
+    remote_head: str | None
+    stale: bool
+    determinable: bool
+    mutation_safe: bool
+    reasons: tuple[str, ...]
+
+
+@dataclass(frozen=True)
+class SystemHealthSnapshot:
+    status: str
+    ready: bool
+    readiness_complete: bool
+    readiness_reasons: tuple[str, ...]
+    service: str
+    mode: str
+    version: VersionInfo
+    started_at: str
+    uptime_seconds: float
+    timestamp: str
+    deep_probes_requested: bool
+    dependencies: tuple[DependencyProbe, ...]
+    mcp_namespaces: tuple[dict[str, Any], ...]
+    stale_runtime: StaleRuntime
+    probe_errors: tuple[str, ...] = ()
+
+
+def process_uptime() -> tuple[str, float]:
+    """Process start timestamp and uptime — in-memory, safe for `/health`."""
+    return _STARTED_AT.isoformat(), round(time.monotonic() - _STARTED_MONOTONIC, 3)
+
+
+def _offline() -> bool:
+    return (os.environ.get(_OFFLINE_ENV) or "").strip().lower() in {"1", "true", "yes"}
+
+
+def _repo_root() -> Path:
+    override = (os.environ.get("WEBUI_REPO_ROOT") or "").strip()
+    if override:
+        return Path(override).resolve()
+    return Path(__file__).resolve().parent.parent
+
+
+def _deep_probe_ttl() -> float:
+    raw = (os.environ.get(_DEEP_PROBE_TTL_ENV) or "").strip()
+    if not raw:
+        return _DEFAULT_DEEP_PROBE_TTL
+    try:
+        value = float(raw)
+    except ValueError:
+        return _DEFAULT_DEEP_PROBE_TTL
+    return value if value >= 0 else _DEFAULT_DEEP_PROBE_TTL
+
+
+def redact(text: str) -> str:
+    """Strip credential-shaped material from operator-visible probe text.
+
+    Probe details carry exception strings, and an exception raised by an HTTP
+    client can quote the request that failed. Redaction happens here, at the
+    boundary where those strings become part of a browser-bound payload.
+    """
+    if not text:
+        return ""
+    cleaned = _redact_urls(text)
+    cleaned = _SECRET_RE.sub(lambda m: f"{m.group(1)}=[redacted]", cleaned)
+    return _LONG_OPAQUE_RE.sub("[redacted]", cleaned)
+
+
+def _redact_urls(text: str) -> str:
+    return re.sub(r"https?://\S+", lambda m: redact_url(m.group(0)), text)
+
+
+def redact_url(url: str) -> str:
+    """Reduce a URL to scheme://host/path — no userinfo, no query, no fragment."""
+    try:
+        parts = urlsplit(url)
+    except ValueError:
+        return "[redacted-url]"
+    if not parts.scheme or not parts.hostname:
+        return "[redacted-url]"
+    netloc = parts.hostname
+    if parts.port:
+        netloc = f"{netloc}:{parts.port}"
+    return urlunsplit((parts.scheme, netloc, parts.path, "", ""))
+
+
+def _git(repo: Path, *args: str) -> str | None:
+    try:
+        completed = subprocess.run(
+            ["git", "-C", str(repo), *args],
+            capture_output=True,
+            text=True,
+            check=False,
+            timeout=10,
+        )
+    except (OSError, subprocess.SubprocessError):
+        return None
+    if completed.returncode != 0:
+        return None
+    return (completed.stdout or "").strip() or None
+
+
+def _load_version(repo: Path, *, schema_version: int | None) -> VersionInfo:
+    import platform
+
+    git_sha = None if _offline() else _git(repo, "rev-parse", "HEAD")
+    describe = None if _offline() else _git(repo, "describe", "--tags", "--always")
+    return VersionInfo(
+        git_sha=git_sha,
+        git_describe=describe,
+        control_plane_schema_version=schema_version,
+        python_version=platform.python_version(),
+        known=bool(git_sha),
+    )
+
+
+# ---------------------------------------------------------------------------
+# Dependency probes
+# ---------------------------------------------------------------------------
+
+
+def _elapsed_ms(started: float) -> float:
+    return round((time.monotonic() - started) * 1000, 3)
+
+
+def probe_control_plane_db(db_path: str | None = None) -> DependencyProbe:
+    """Read-only reachability check for the control-plane SQLite substrate.
+
+    Opened through a ``mode=ro`` URI on purpose: ``ControlPlaneDB.__init__``
+    creates directories and runs schema migrations, which a health check must
+    never do.
+    """
+    path = (db_path or control_plane_db.default_db_path()).strip()
+    started = time.monotonic()
+    metadata: dict[str, Any] = {"path": path}
+
+    def _result(status: str, detail: str) -> DependencyProbe:
+        return DependencyProbe(
+            name="control_plane_db",
+            kind="sqlite",
+            status=status,
+            detail=detail,
+            required=True,
+            latency_ms=_elapsed_ms(started),
+            metadata=metadata,
+        )
+
+    if not path or not os.path.exists(path):
+        return _result(STATUS_DOWN, "control-plane database file does not exist yet")
+    try:
+        conn = sqlite3.connect(f"file:{path}?mode=ro", uri=True, timeout=5)
+        try:
+            row = conn.execute(
+                "SELECT value FROM schema_meta WHERE key = 'schema_version'"
+            ).fetchone()
+            leases = conn.execute(
+                "SELECT COUNT(*) FROM leases WHERE status = 'active'"
+            ).fetchone()
+        finally:
+            conn.close()
+    except sqlite3.Error as exc:
+        return _result(STATUS_DOWN, redact(f"control-plane database unreadable: {exc}"))
+
+    schema_version = int(row[0]) if row and str(row[0]).isdigit() else None
+    metadata["schema_version"] = schema_version
+    metadata["active_leases"] = int(leases[0]) if leases else None
+    if schema_version is None:
+        return _result(
+            STATUS_DEGRADED, "control-plane database has no recorded schema version"
+        )
+    if schema_version != control_plane_db.SCHEMA_VERSION:
+        return _result(
+            STATUS_DEGRADED,
+            f"control-plane schema version {schema_version} does not match the "
+            f"version this code expects ({control_plane_db.SCHEMA_VERSION})",
+        )
+    return _result(STATUS_OK, f"schema v{schema_version} readable")
+
+
+def probe_repository(repo: Path) -> DependencyProbe:
+    """Local checkout reachability — required, cheap, no network."""
+    started = time.monotonic()
+    metadata: dict[str, Any] = {"repo_root": str(repo)}
+    if _offline():
+        return DependencyProbe(
+            name="repository",
+            kind="git",
+            status=STATUS_SKIPPED,
+            detail=f"{_OFFLINE_ENV} is set; git probe skipped",
+            required=True,
+            latency_ms=_elapsed_ms(started),
+            metadata=metadata,
+        )
+    head = _git(repo, "rev-parse", "HEAD")
+    if not head:
+        return DependencyProbe(
+            name="repository",
+            kind="git",
+            status=STATUS_DOWN,
+            detail=f"HEAD could not be read at {repo}",
+            required=True,
+            latency_ms=_elapsed_ms(started),
+            metadata=metadata,
+        )
+    branch = _git(repo, "rev-parse", "--abbrev-ref", "HEAD")
+    metadata["head"] = head
+    metadata["branch"] = branch
+    return DependencyProbe(
+        name="repository",
+        kind="git",
+        status=STATUS_OK,
+        detail=f"checkout readable at {branch or 'detached HEAD'}",
+        required=True,
+        latency_ms=_elapsed_ms(started),
+        metadata=metadata,
+    )
+
+
+def probe_gitea(host: str) -> DependencyProbe:
+    """Live Gitea reachability. Expensive (network), so opt-in via ``deep``.
+
+    Optional by design: the console stays useful for local inventory when the
+    remote is unreachable, so a failure here degrades status without claiming
+    the process itself is unready.
+    """
+    started = time.monotonic()
+    metadata: dict[str, Any] = {"host": host}
+
+    def _failure(status: str, detail: str) -> DependencyProbe:
+        return DependencyProbe(
+            name="gitea",
+            kind="http",
+            status=status,
+            detail=detail,
+            required=False,
+            latency_ms=_elapsed_ms(started),
+            metadata=metadata,
+        )
+
+    if not host:
+        return _failure(STATUS_DEGRADED, "no Gitea host is configured in the registry")
+    try:
+        auth = get_auth_header(host)
+    except Exception as exc:  # noqa: BLE001 — credential guards are a status here
+        return _failure(STATUS_DEGRADED, redact(f"credential lookup refused: {exc}"))
+    if not auth:
+        return _failure(STATUS_DEGRADED, f"no credentials available for {host}")
+
+    url = gitea_url(host, "/api/v1/version")
+    metadata["endpoint"] = redact_url(url)
+    try:
+        data = api_request("GET", url, auth, timeout=_GITEA_PROBE_TIMEOUT_SECONDS)
+    except Exception as exc:  # noqa: BLE001 — a down dependency is a status
+        return _failure(STATUS_DOWN, redact(f"Gitea probe failed: {exc}"))
+
+    if isinstance(data, dict) and data.get("version"):
+        metadata["gitea_version"] = str(data["version"])
+    return DependencyProbe(
+        name="gitea",
+        kind="http",
+        status=STATUS_OK,
+        detail=f"{host} reachable",
+        required=False,
+        latency_ms=_elapsed_ms(started),
+        metadata=metadata,
+    )
+
+
+def _skipped_gitea(host: str) -> DependencyProbe:
+    return DependencyProbe(
+        name="gitea",
+        kind="http",
+        status=STATUS_SKIPPED,
+        detail="network probe not requested; call with ?deep=1 to run it",
+        required=False,
+        latency_ms=None,
+        metadata={"host": host},
+    )
+
+
+def namespace_summaries() -> tuple[dict[str, Any], ...]:
+    """Declared MCP namespaces, each honestly reported as unproven.
+
+    The web process runs outside the IDE-managed MCP client, so it cannot
+    invoke a namespace tool. Per #543 only a ``client_namespace`` probe proves
+    that path, and inventing a healthy verdict here is exactly the false claim
+    the mutation gates exist to prevent.
+    """
+    rows: list[dict[str, Any]] = []
+    for namespace, required_tool in sorted(
+        mcp_namespace_health.REQUIRED_NAMESPACE_TOOLS.items()
+    ):
+        classification = mcp_namespace_health.classify_namespace_probe(
+            namespace,
+            required_tool=required_tool,
+            probe_result=None,
+            probe_source=mcp_namespace_health.PROBE_SOURCE_UNKNOWN,
+        )
+        rows.append(
+            {
+                "namespace": namespace,
+                "required_tool": required_tool,
+                "status": STATUS_UNPROVEN,
+                "ide_namespace_proven": bool(classification.get("ide_namespace_proven")),
+                "reason": (
+                    "the web console cannot invoke the IDE-managed MCP client; "
+                    "namespace health must be proven with a client_namespace "
+                    "probe (#543)"
+                ),
+                "error_type": classification.get("error_type"),
+            }
+        )
+    return tuple(rows)
+
+
+def assess_stale_runtime(
+    repo: Path,
+    *,
+    daemon_head: str | None = None,
+    git_reader: Callable[..., str | None] | None = None,
+) -> StaleRuntime:
+    """Three-way parity view: running code, local checkout, remote-tracking ref.
+
+    ``mutation_safe`` requires all three to be known and equal. Anything less —
+    including "the remote ref was never fetched" — is reported as not safe with
+    a reason, so an operator never reads an unproven green.
+    """
+    reader = git_reader or (lambda *args: _git(repo, *args))
+    reasons: list[str] = []
+    # The offline switch suppresses real subprocess calls; an explicitly
+    # injected reader is already a substitute for them and is always used.
+    offline = _offline() and git_reader is None
+
+    checkout_head = None if offline else reader("rev-parse", "HEAD")
+    remote_head = None if offline else reader("rev-parse", "@{upstream}")
+    if offline:
+        reasons.append(f"{_OFFLINE_ENV} is set; parity commits were not read")
+    else:
+        if checkout_head is None:
+            reasons.append("local checkout HEAD could not be read")
+        if remote_head is None:
+            reasons.append(
+                "no remote-tracking commit is known for the current branch; "
+                "remote staleness is indeterminate (no fetch is performed here)"
+            )
+
+    effective_daemon = daemon_head if daemon_head is not None else checkout_head
+    if daemon_head is None:
+        reasons.append(
+            "the running MCP daemon's startup commit is not observable from the "
+            "web process; the checkout commit is reported in its place"
+        )
+
+    determinable = bool(checkout_head and remote_head and effective_daemon)
+    stale = bool(
+        determinable and len({checkout_head, remote_head, effective_daemon}) > 1
+    )
+    if stale:
+        reasons.append(
+            "runtime, checkout, and remote commits disagree; restart the MCP "
+            "server after updating the checkout before trusting capability gates"
+        )
+
+    return StaleRuntime(
+        daemon_head=effective_daemon,
+        checkout_head=checkout_head,
+        remote_head=remote_head,
+        stale=stale,
+        determinable=determinable,
+        mutation_safe=bool(determinable and not stale),
+        reasons=tuple(reasons),
+    )
+
+
+# ---------------------------------------------------------------------------
+# Snapshot assembly
+# ---------------------------------------------------------------------------
+
+
+def _default_host() -> str:
+    registry = load_registry()
+    if not registry.projects:
+        return ""
+    raw = registry.projects[0].remote_host
+    parts = urlsplit(raw.strip())
+    return parts.netloc or raw.strip().rstrip("/")
+
+
+def _aggregate(
+    probes: tuple[DependencyProbe, ...],
+) -> tuple[str, bool, bool, tuple[str, ...]]:
+    """Fold probe results into overall status and readiness.
+
+    Required probes drive readiness; optional probes can only degrade status.
+    A probe that did not run leaves readiness incomplete rather than passing.
+    """
+    reasons: list[str] = []
+    required = [probe for probe in probes if probe.required]
+    unrun_required = [probe for probe in required if not probe.ran]
+    failed_required = [probe for probe in required if probe.ran and not probe.healthy]
+    failed_optional = [
+        probe
+        for probe in probes
+        if not probe.required and probe.ran and not probe.healthy
+    ]
+
+    for probe in unrun_required:
+        reasons.append(
+            f"required dependency '{probe.name}' was not probed: {probe.detail}"
+        )
+    for probe in failed_required:
+        reasons.append(
+            f"required dependency '{probe.name}' is {probe.status}: {probe.detail}"
+        )
+    for probe in failed_optional:
+        reasons.append(
+            f"optional dependency '{probe.name}' is {probe.status}: {probe.detail}"
+        )
+
+    readiness_complete = not unrun_required
+    ready = readiness_complete and not failed_required
+
+    if any(probe.status == STATUS_DOWN for probe in failed_required):
+        status = STATUS_DOWN
+    elif failed_required or failed_optional or unrun_required:
+        status = STATUS_DEGRADED
+    else:
+        status = STATUS_OK
+    return status, ready, readiness_complete, tuple(reasons)
+
+
+def load_system_health(
+    *,
+    deep: bool = False,
+    host: str | None = None,
+    probes: tuple[DependencyProbe, ...] | None = None,
+    daemon_head: str | None = None,
+    use_cache: bool = True,
+) -> SystemHealthSnapshot:
+    """Assemble the read-only system-health snapshot.
+
+    ``deep=True`` adds the network probe against Gitea; its result is cached for
+    a short TTL so repeated dashboard polls do not amplify into remote load.
+    """
+    repo = _repo_root()
+    probe_errors: list[str] = []
+
+    if probes is None:
+        collected: list[DependencyProbe] = []
+        for probe_fn in (
+            lambda: probe_control_plane_db(),
+            lambda: probe_repository(repo),
+        ):
+            try:
+                collected.append(probe_fn())
+            except Exception as exc:  # noqa: BLE001 — a probe must not 500 the API
+                probe_errors.append(redact(f"probe raised: {exc}"))
+        resolved_host = host if host is not None else _default_host()
+        if deep and not _offline():
+            collected.append(_cached_gitea_probe(resolved_host, use_cache=use_cache))
+        else:
+            collected.append(_skipped_gitea(resolved_host))
+        probes = tuple(collected)
+
+    status, ready, readiness_complete, reasons = _aggregate(probes)
+    stale = assess_stale_runtime(repo, daemon_head=daemon_head)
+    if stale.stale:
+        if status == STATUS_OK:
+            status = STATUS_DEGRADED
+        reasons = reasons + (
+            "runtime is stale relative to its remote-tracking commit",
+        )
+
+    db_probe = next((p for p in probes if p.name == "control_plane_db"), None)
+    schema_version = None
+    if db_probe and db_probe.metadata:
+        schema_version = db_probe.metadata.get("schema_version")
+
+    return SystemHealthSnapshot(
+        status=status,
+        ready=ready,
+        readiness_complete=readiness_complete,
+        readiness_reasons=reasons,
+        service=SERVICE_NAME,
+        mode="read-only",
+        version=_load_version(repo, schema_version=schema_version),
+        started_at=_STARTED_AT.isoformat(),
+        uptime_seconds=round(time.monotonic() - _STARTED_MONOTONIC, 3),
+        timestamp=datetime.now(timezone.utc).isoformat(),
+        deep_probes_requested=deep,
+        dependencies=probes,
+        mcp_namespaces=namespace_summaries(),
+        stale_runtime=stale,
+        probe_errors=tuple(probe_errors),
+    )
+
+
+def _cached_gitea_probe(host: str, *, use_cache: bool = True) -> DependencyProbe:
+    ttl = _deep_probe_ttl()
+    now = time.monotonic()
+    if use_cache and ttl > 0:
+        cached = _deep_cache.get(host)
+        if cached and (now - cached[0]) < ttl:
+            return cached[1]
+    probe = probe_gitea(host)
+    if use_cache and ttl > 0:
+        _deep_cache[host] = (now, probe)
+    return probe
+
+
+def clear_probe_cache() -> None:
+    """Drop cached deep-probe results (tests and operator-forced refresh)."""
+    _deep_cache.clear()
+
+
+def probe_to_dict(probe: DependencyProbe) -> dict[str, Any]:
+    return {
+        "name": probe.name,
+        "kind": probe.kind,
+        "status": probe.status,
+        "detail": probe.detail,
+        "required": probe.required,
+        "healthy": probe.healthy,
+        "latency_ms": probe.latency_ms,
+        "metadata": dict(probe.metadata or {}),
+    }
+
+
+def snapshot_to_dict(snapshot: SystemHealthSnapshot) -> dict[str, Any]:
+    return {
+        "status": snapshot.status,
+        "service": snapshot.service,
+        "mode": snapshot.mode,
+        "api": API_PATH,
+        "timestamp": snapshot.timestamp,
+        "readiness": {
+            "ready": snapshot.ready,
+            "complete": snapshot.readiness_complete,
+            "reasons": list(snapshot.readiness_reasons),
+        },
+        "version": {
+            "git_sha": snapshot.version.git_sha,
+            "git_describe": snapshot.version.git_describe,
+            "control_plane_schema_version": (
+                snapshot.version.control_plane_schema_version
+            ),
+            "python_version": snapshot.version.python_version,
+            "known": snapshot.version.known,
+        },
+        "process": {
+            "started_at": snapshot.started_at,
+            "uptime_seconds": snapshot.uptime_seconds,
+        },
+        "deep_probes_requested": snapshot.deep_probes_requested,
+        "dependencies": [probe_to_dict(probe) for probe in snapshot.dependencies],
+        "mcp_namespaces": [dict(row) for row in snapshot.mcp_namespaces],
+        "stale_runtime": {
+            "daemon_head": snapshot.stale_runtime.daemon_head,
+            "checkout_head": snapshot.stale_runtime.checkout_head,
+            "remote_head": snapshot.stale_runtime.remote_head,
+            "stale": snapshot.stale_runtime.stale,
+            "determinable": snapshot.stale_runtime.determinable,
+            "mutation_safe": snapshot.stale_runtime.mutation_safe,
+            "reasons": list(snapshot.stale_runtime.reasons),
+        },
+        "probe_errors": list(snapshot.probe_errors),
+    }

webui/worker_registry.py

@@ -0,0 +1,647 @@
+"""Declarative worker registry and configuration schema (#798, epic #797).
+
+The registry is the single source of truth for the scheduled multi-LLM worker
+fleet. It is a versioned JSON document holding two *separate* entity kinds:
+
+* **Providers** — the LLM runtimes a worker can be built on (Claude, Grok,
+  Codex, AGY, Kimi K). A provider describes the runtime itself: vendor,
+  executable name, models it can serve, and whether it is available on this
+  machine. Providers exist whether or not any worker uses them.
+* **Workers** — a configured *instance*: one provider, one model, one project,
+  one role, one MCP namespace/profile, one workflow, one schedule. Several
+  workers may share a provider; a worker naming an undeclared provider is
+  refused.
+
+Keeping them separate is what lets #799 list all five providers even when a
+provider currently has no configured worker, and it stops provider facts from
+being copied into (and drifting across) every worker record.
+
+Scope boundary. This module owns the data model, its validation, and its
+persistence. It does **not** schedule anything, launch anything, probe provider
+executables, or serve HTTP. Loading a registry never touches a process; the
+live fields a dashboard wants (PID, elapsed time, next run) are derived
+elsewhere (#799, #801, #803, #804) from these declarations.
+
+Safety invariants:
+
+* No credential may be stored (:mod:`webui.registry_safety`), so the registry
+  stays safe to render and to hand to a browser layer.
+* Validation fails closed. Unknown fields are refused rather than ignored, so a
+  typo cannot silently disable a timeout or a role binding.
+* Writes are atomic and every superseded document is retained as a numbered
+  revision, so a bad edit is recoverable by rollback rather than hand-repair.
+"""
+
+from __future__ import annotations
+
+import json
+import os
+import re
+import tempfile
+from dataclasses import dataclass
+from datetime import datetime, timezone
+from pathlib import Path
+from typing import Any
+
+from webui.registry_safety import reject_credential_keys
+
+SCHEMA_VERSION = 1
+
+#: Roles a worker may hold. These mirror the sanctioned MCP role kinds; a
+#: worker may not invent one, because the role selects the namespace/profile
+#: whose capability gates constrain it.
+ALLOWED_ROLES = ("author", "reviewer", "merger", "reconciler", "cleanup")
+
+#: Scheduler backends the registry can describe. ``manual`` means the worker is
+#: only ever started on request and has no recurring trigger.
+ALLOWED_SCHEDULER_KINDS = ("launchd", "manual")
+
+#: Schedule kinds. Next-run computation belongs to #803; this module only
+#: guarantees the declaration is well formed.
+ALLOWED_SCHEDULE_KINDS = ("interval", "cron", "manual")
+
+_REQUIRED_PROVIDER_FIELDS = ("id", "display_name", "vendor", "executable", "available")
+_OPTIONAL_PROVIDER_FIELDS = ("models", "notes")
+
+_REQUIRED_WORKER_FIELDS = (
+    "id",
+    "display_name",
+    "provider",
+    "model",
+    "project",
+    "role",
+    "namespace",
+    "profile",
+    "workflow",
+    "schedule",
+    "timeout_seconds",
+    "enabled",
+    "scheduler",
+)
+_OPTIONAL_WORKER_FIELDS = ("notes",)
+
+_ID_RE = re.compile(r"^[a-z0-9][a-z0-9._-]*$")
+
+#: Guards against an operator writing a timeout that would let a worker hold a
+#: lease effectively forever. 24h is far above any sanctioned cycle.
+_MAX_TIMEOUT_SECONDS = 86_400
+
+#: How many superseded revisions to retain beside the live file.
+_HISTORY_LIMIT = 20
+
+_TOP_LEVEL_FIELDS = frozenset({"version", "revision", "updated_at", "providers", "workers"})
+
+
+class RegistryValidationError(ValueError):
+    """Raised when a registry document violates the schema."""
+
+
+@dataclass(frozen=True)
+class ProviderRecord:
+    id: str
+    display_name: str
+    vendor: str
+    executable: str
+    available: bool
+    models: tuple[str, ...]
+    notes: str
+
+
+@dataclass(frozen=True)
+class ScheduleSpec:
+    kind: str
+    #: Set for ``interval`` schedules.
+    seconds: int | None
+    #: Set for ``cron`` schedules — a five-field crontab expression.
+    expression: str | None
+
+
+@dataclass(frozen=True)
+class SchedulerSpec:
+    kind: str
+    #: LaunchAgent label; required for ``launchd``, absent for ``manual``.
+    label: str | None
+
+
+@dataclass(frozen=True)
+class WorkerRecord:
+    id: str
+    display_name: str
+    provider: str
+    model: str
+    project: str
+    role: str
+    namespace: str
+    profile: str
+    workflow: str
+    schedule: ScheduleSpec
+    timeout_seconds: int
+    enabled: bool
+    scheduler: SchedulerSpec
+    notes: str
+
+
+@dataclass(frozen=True)
+class WorkerRegistry:
+    version: int
+    revision: int
+    updated_at: str
+    providers: tuple[ProviderRecord, ...]
+    workers: tuple[WorkerRecord, ...]
+    source_path: Path
+
+
+# ── paths ────────────────────────────────────────────────────────────────────
+
+
+def default_registry_path() -> Path:
+    """Location of the packaged worker registry, overridable for tests/deploys."""
+    override = os.environ.get("WEBUI_WORKER_REGISTRY", "").strip()
+    if override:
+        return Path(override).expanduser().resolve()
+    return (Path(__file__).resolve().parent / "data" / "workers.registry.json").resolve()
+
+
+def history_dir(path: Path | None = None) -> Path:
+    """Directory holding superseded revisions of *path*."""
+    source = (path or default_registry_path()).resolve()
+    return source.parent / f"{source.name}.history"
+
+
+# ── field helpers ────────────────────────────────────────────────────────────
+
+
+def _require_exact_fields(
+    raw: Any,
+    *,
+    required: tuple[str, ...],
+    optional: tuple[str, ...],
+    subject: str,
+) -> dict[str, Any]:
+    if not isinstance(raw, dict):
+        raise RegistryValidationError(f"{subject} must be an object")
+    missing = [field for field in required if field not in raw]
+    if missing:
+        raise RegistryValidationError(
+            f"{subject} missing required fields: {', '.join(sorted(missing))}"
+        )
+    unknown = sorted(set(raw) - set(required) - set(optional))
+    if unknown:
+        # Fail closed: silently dropping an unrecognized key is how a typo'd
+        # "timeout_second" ends up meaning "no timeout".
+        raise RegistryValidationError(f"{subject} has unknown fields: {', '.join(unknown)}")
+    return raw
+
+
+def _require_identifier(value: Any, *, subject: str) -> str:
+    text = str(value).strip()
+    if not _ID_RE.match(text):
+        raise RegistryValidationError(
+            f"{subject} must be lowercase alphanumeric with '.', '_', or '-' (got {value!r})"
+        )
+    return text
+
+
+def _require_text(value: Any, *, subject: str) -> str:
+    if not isinstance(value, str):
+        raise RegistryValidationError(f"{subject} must be a string (got {value!r})")
+    text = value.strip()
+    if not text:
+        raise RegistryValidationError(f"{subject} must be a non-empty string")
+    return text
+
+
+def _require_bool(value: Any, *, subject: str) -> bool:
+    if not isinstance(value, bool):
+        raise RegistryValidationError(f"{subject} must be a boolean (got {value!r})")
+    return value
+
+
+def _require_positive_int(value: Any, *, subject: str, maximum: int | None = None) -> int:
+    if isinstance(value, bool) or not isinstance(value, int):
+        raise RegistryValidationError(f"{subject} must be an integer (got {value!r})")
+    if value <= 0:
+        raise RegistryValidationError(f"{subject} must be greater than zero (got {value})")
+    if maximum is not None and value > maximum:
+        raise RegistryValidationError(f"{subject} must not exceed {maximum} (got {value})")
+    return value
+
+
+# ── parsing ──────────────────────────────────────────────────────────────────
+
+
+def _parse_provider(raw: Any) -> ProviderRecord:
+    data = _require_exact_fields(
+        raw,
+        required=_REQUIRED_PROVIDER_FIELDS,
+        optional=_OPTIONAL_PROVIDER_FIELDS,
+        subject="provider",
+    )
+    provider_id = _require_identifier(data["id"], subject="provider.id")
+
+    models_raw = data.get("models") or []
+    if not isinstance(models_raw, list):
+        raise RegistryValidationError(f"provider[{provider_id}].models must be an array")
+    models = tuple(
+        _require_text(item, subject=f"provider[{provider_id}].models[]") for item in models_raw
+    )
+
+    return ProviderRecord(
+        id=provider_id,
+        display_name=_require_text(
+            data["display_name"], subject=f"provider[{provider_id}].display_name"
+        ),
+        vendor=_require_text(data["vendor"], subject=f"provider[{provider_id}].vendor"),
+        executable=_require_text(data["executable"], subject=f"provider[{provider_id}].executable"),
+        available=_require_bool(data["available"], subject=f"provider[{provider_id}].available"),
+        models=models,
+        notes=str(data.get("notes") or "").strip(),
+    )
+
+
+def _parse_schedule(raw: Any, *, subject: str) -> ScheduleSpec:
+    if not isinstance(raw, dict):
+        raise RegistryValidationError(f"{subject} must be an object")
+    kind = _require_text(raw.get("kind"), subject=f"{subject}.kind")
+    if kind not in ALLOWED_SCHEDULE_KINDS:
+        raise RegistryValidationError(
+            f"{subject}.kind must be one of {', '.join(ALLOWED_SCHEDULE_KINDS)} (got {kind!r})"
+        )
+
+    seconds: int | None = None
+    expression: str | None = None
+
+    if kind == "interval":
+        if "seconds" not in raw:
+            raise RegistryValidationError(f"{subject}.seconds is required for interval schedules")
+        seconds = _require_positive_int(raw["seconds"], subject=f"{subject}.seconds")
+    elif kind == "cron":
+        if "expression" not in raw:
+            raise RegistryValidationError(f"{subject}.expression is required for cron schedules")
+        expression = _require_text(raw["expression"], subject=f"{subject}.expression")
+        if len(expression.split()) != 5:
+            raise RegistryValidationError(
+                f"{subject}.expression must have five crontab fields (got {expression!r})"
+            )
+
+    allowed = {"kind"}
+    if kind == "interval":
+        allowed.add("seconds")
+    elif kind == "cron":
+        allowed.add("expression")
+    unknown = sorted(set(raw) - allowed)
+    if unknown:
+        raise RegistryValidationError(
+            f"{subject} has fields not valid for kind {kind!r}: {', '.join(unknown)}"
+        )
+
+    return ScheduleSpec(kind=kind, seconds=seconds, expression=expression)
+
+
+def _parse_scheduler(raw: Any, *, subject: str) -> SchedulerSpec:
+    if not isinstance(raw, dict):
+        raise RegistryValidationError(f"{subject} must be an object")
+    kind = _require_text(raw.get("kind"), subject=f"{subject}.kind")
+    if kind not in ALLOWED_SCHEDULER_KINDS:
+        raise RegistryValidationError(
+            f"{subject}.kind must be one of {', '.join(ALLOWED_SCHEDULER_KINDS)} (got {kind!r})"
+        )
+
+    label: str | None = None
+    if kind == "launchd":
+        if "label" not in raw:
+            raise RegistryValidationError(f"{subject}.label is required for launchd schedulers")
+        label = _require_text(raw["label"], subject=f"{subject}.label")
+
+    allowed = {"kind"}
+    if kind == "launchd":
+        allowed.add("label")
+    unknown = sorted(set(raw) - allowed)
+    if unknown:
+        raise RegistryValidationError(
+            f"{subject} has fields not valid for kind {kind!r}: {', '.join(unknown)}"
+        )
+
+    return SchedulerSpec(kind=kind, label=label)
+
+
+def _parse_worker(raw: Any) -> WorkerRecord:
+    data = _require_exact_fields(
+        raw,
+        required=_REQUIRED_WORKER_FIELDS,
+        optional=_OPTIONAL_WORKER_FIELDS,
+        subject="worker",
+    )
+    worker_id = _require_identifier(data["id"], subject="worker.id")
+
+    role = _require_text(data["role"], subject=f"worker[{worker_id}].role")
+    if role not in ALLOWED_ROLES:
+        raise RegistryValidationError(
+            f"worker[{worker_id}].role must be one of {', '.join(ALLOWED_ROLES)} (got {role!r})"
+        )
+
+    return WorkerRecord(
+        id=worker_id,
+        display_name=_require_text(
+            data["display_name"], subject=f"worker[{worker_id}].display_name"
+        ),
+        provider=_require_identifier(data["provider"], subject=f"worker[{worker_id}].provider"),
+        model=_require_text(data["model"], subject=f"worker[{worker_id}].model"),
+        project=_require_text(data["project"], subject=f"worker[{worker_id}].project"),
+        role=role,
+        namespace=_require_text(data["namespace"], subject=f"worker[{worker_id}].namespace"),
+        profile=_require_text(data["profile"], subject=f"worker[{worker_id}].profile"),
+        workflow=_require_text(data["workflow"], subject=f"worker[{worker_id}].workflow"),
+        schedule=_parse_schedule(data["schedule"], subject=f"worker[{worker_id}].schedule"),
+        timeout_seconds=_require_positive_int(
+            data["timeout_seconds"],
+            subject=f"worker[{worker_id}].timeout_seconds",
+            maximum=_MAX_TIMEOUT_SECONDS,
+        ),
+        enabled=_require_bool(data["enabled"], subject=f"worker[{worker_id}].enabled"),
+        scheduler=_parse_scheduler(data["scheduler"], subject=f"worker[{worker_id}].scheduler"),
+        notes=str(data.get("notes") or "").strip(),
+    )
+
+
+def _require_unique(values: list[str], *, subject: str) -> None:
+    seen: set[str] = set()
+    for value in values:
+        if value in seen:
+            raise RegistryValidationError(f"duplicate {subject}: {value}")
+        seen.add(value)
+
+
+def validate_payload(payload: Any, *, source_path: Path) -> WorkerRegistry:
+    """Validate a decoded registry document and return the typed registry.
+
+    Raises :class:`RegistryValidationError` on any violation; never partially
+    accepts a document.
+    """
+    if not isinstance(payload, dict):
+        raise RegistryValidationError("registry root must be an object")
+
+    version = payload.get("version")
+    if version != SCHEMA_VERSION:
+        raise RegistryValidationError(f"unsupported registry version: {version!r}")
+
+    reject_credential_keys(payload, subject="worker registry")
+
+    unknown = sorted(set(payload) - _TOP_LEVEL_FIELDS)
+    if unknown:
+        raise RegistryValidationError(f"registry has unknown fields: {', '.join(unknown)}")
+
+    revision = _require_positive_int(payload.get("revision"), subject="revision")
+    updated_at = _require_text(payload.get("updated_at"), subject="updated_at")
+
+    providers_raw = payload.get("providers")
+    if not isinstance(providers_raw, list) or not providers_raw:
+        raise RegistryValidationError("providers must be a non-empty array")
+    providers = tuple(_parse_provider(item) for item in providers_raw)
+    _require_unique([provider.id for provider in providers], subject="provider id")
+
+    workers_raw = payload.get("workers")
+    if not isinstance(workers_raw, list):
+        raise RegistryValidationError("workers must be an array")
+    workers = tuple(_parse_worker(item) for item in workers_raw)
+    _require_unique([worker.id for worker in workers], subject="worker id")
+
+    # Referential integrity: a worker naming an undeclared provider would look
+    # configured while being unrunnable, which is exactly the ambiguous
+    # ownership the epic requires to fail closed.
+    known_providers = {provider.id for provider in providers}
+    for worker in workers:
+        if worker.provider not in known_providers:
+            raise RegistryValidationError(
+                f"worker[{worker.id}].provider references unknown provider {worker.provider!r}"
+            )
+
+    # A LaunchAgent label identifies a job to launchd; two workers sharing one
+    # would silently overwrite each other's agent.
+    _require_unique(
+        [worker.scheduler.label for worker in workers if worker.scheduler.label],
+        subject="scheduler label",
+    )
+
+    return WorkerRegistry(
+        version=version,
+        revision=revision,
+        updated_at=updated_at,
+        providers=providers,
+        workers=workers,
+        source_path=source_path,
+    )
+
+
+def load_registry(path: Path | None = None) -> WorkerRegistry:
+    """Load and validate the worker registry from disk."""
+    source = (path or default_registry_path()).resolve()
+    payload = json.loads(source.read_text(encoding="utf-8"))
+    return validate_payload(payload, source_path=source)
+
+
+# ── serialization ────────────────────────────────────────────────────────────
+
+
+def provider_to_dict(provider: ProviderRecord) -> dict[str, Any]:
+    return {
+        "id": provider.id,
+        "display_name": provider.display_name,
+        "vendor": provider.vendor,
+        "executable": provider.executable,
+        "available": provider.available,
+        "models": list(provider.models),
+        "notes": provider.notes,
+    }
+
+
+def _schedule_to_dict(schedule: ScheduleSpec) -> dict[str, Any]:
+    payload: dict[str, Any] = {"kind": schedule.kind}
+    if schedule.kind == "interval":
+        payload["seconds"] = schedule.seconds
+    elif schedule.kind == "cron":
+        payload["expression"] = schedule.expression
+    return payload
+
+
+def _scheduler_to_dict(scheduler: SchedulerSpec) -> dict[str, Any]:
+    payload: dict[str, Any] = {"kind": scheduler.kind}
+    if scheduler.kind == "launchd":
+        payload["label"] = scheduler.label
+    return payload
+
+
+def worker_to_dict(worker: WorkerRecord) -> dict[str, Any]:
+    return {
+        "id": worker.id,
+        "display_name": worker.display_name,
+        "provider": worker.provider,
+        "model": worker.model,
+        "project": worker.project,
+        "role": worker.role,
+        "namespace": worker.namespace,
+        "profile": worker.profile,
+        "workflow": worker.workflow,
+        "schedule": _schedule_to_dict(worker.schedule),
+        "timeout_seconds": worker.timeout_seconds,
+        "enabled": worker.enabled,
+        "scheduler": _scheduler_to_dict(worker.scheduler),
+        "notes": worker.notes,
+    }
+
+
+def registry_to_document(registry: WorkerRegistry) -> dict[str, Any]:
+    """Serialize to the on-disk document shape (no local paths embedded)."""
+    return {
+        "version": registry.version,
+        "revision": registry.revision,
+        "updated_at": registry.updated_at,
+        "providers": [provider_to_dict(provider) for provider in registry.providers],
+        "workers": [worker_to_dict(worker) for worker in registry.workers],
+    }
+
+
+def registry_to_dict(registry: WorkerRegistry) -> dict[str, Any]:
+    """Serialize for JSON API responses (adds the resolved source path)."""
+    document = registry_to_document(registry)
+    document["source_path"] = str(registry.source_path)
+    return document
+
+
+def find_worker(registry: WorkerRegistry, worker_id: str) -> WorkerRecord | None:
+    for worker in registry.workers:
+        if worker.id == worker_id:
+            return worker
+    return None
+
+
+def find_provider(registry: WorkerRegistry, provider_id: str) -> ProviderRecord | None:
+    for provider in registry.providers:
+        if provider.id == provider_id:
+            return provider
+    return None
+
+
+def workers_for_provider(registry: WorkerRegistry, provider_id: str) -> tuple[WorkerRecord, ...]:
+    return tuple(worker for worker in registry.workers if worker.provider == provider_id)
+
+
+# ── persistence ──────────────────────────────────────────────────────────────
+
+
+def _utc_now() -> str:
+    return datetime.now(timezone.utc).strftime("%Y-%m-%dT%H:%M:%SZ")
+
+
+def _atomic_write(path: Path, payload: str) -> None:
+    """Write *payload* to *path* atomically: temp file in the same dir, fsync, replace."""
+    parent = path.parent
+    parent.mkdir(parents=True, exist_ok=True)
+    fd, temp_path = tempfile.mkstemp(prefix=f".{path.name}-", suffix=".tmp", dir=parent)
+    try:
+        with os.fdopen(fd, "w", encoding="utf-8") as handle:
+            handle.write(payload)
+            handle.flush()
+            os.fsync(handle.fileno())
+        os.replace(temp_path, path)
+    finally:
+        if os.path.exists(temp_path):
+            try:
+                os.remove(temp_path)
+            except OSError:
+                pass
+
+
+def _revision_path(directory: Path, revision: int) -> Path:
+    return directory / f"rev-{revision:06d}.json"
+
+
+def _prune_history(path: Path) -> None:
+    directory = history_dir(path)
+    revisions = list_revisions(path)
+    excess = len(revisions) - _HISTORY_LIMIT
+    for revision in revisions[: max(0, excess)]:
+        _revision_path(directory, revision).unlink(missing_ok=True)
+
+
+def _archive_current(path: Path) -> int | None:
+    """Copy the live document into the history dir under its own revision number."""
+    if not path.exists():
+        return None
+    try:
+        existing = json.loads(path.read_text(encoding="utf-8"))
+        revision = int(existing.get("revision", 0))
+    except (json.JSONDecodeError, TypeError, ValueError, AttributeError):
+        # An unreadable live file has no trustworthy revision number to file it
+        # under, so it cannot join the history chain.
+        return None
+    if revision <= 0:
+        return None
+    _atomic_write(
+        _revision_path(history_dir(path), revision),
+        json.dumps(existing, indent=2, sort_keys=True) + "\n",
+    )
+    _prune_history(path)
+    return revision
+
+
+def list_revisions(path: Path | None = None) -> tuple[int, ...]:
+    """Revision numbers retained in history for *path*, oldest first."""
+    directory = history_dir(path)
+    if not directory.is_dir():
+        return ()
+    revisions: list[int] = []
+    for entry in directory.glob("rev-*.json"):
+        try:
+            revisions.append(int(entry.stem.split("-", 1)[1]))
+        except (IndexError, ValueError):
+            continue
+    return tuple(sorted(revisions))
+
+
+def save_registry(
+    registry: WorkerRegistry,
+    path: Path | None = None,
+    *,
+    updated_at: str | None = None,
+) -> WorkerRegistry:
+    """Validate, archive the superseded revision, then atomically persist a new one.
+
+    The stored revision is always the previous revision plus one, so a reader
+    can tell two documents apart even when their content is otherwise equal.
+    Returns the registry exactly as persisted.
+    """
+    target = (path or registry.source_path or default_registry_path()).resolve()
+
+    document = registry_to_document(registry)
+    # Re-validate before writing: a registry assembled in memory has not
+    # necessarily been through the loader.
+    validate_payload(document, source_path=target)
+
+    archived = _archive_current(target)
+    document["revision"] = (archived + 1) if archived is not None else registry.revision
+    document["updated_at"] = updated_at or _utc_now()
+
+    persisted = validate_payload(document, source_path=target)
+    _atomic_write(target, json.dumps(document, indent=2, sort_keys=True) + "\n")
+    return persisted
+
+
+def rollback_to_revision(revision: int, path: Path | None = None) -> WorkerRegistry:
+    """Restore a retained *revision* as a new head revision.
+
+    History is append-only: rolling back does not delete the revisions in
+    between, it republishes the chosen one under the next revision number, so a
+    rollback is itself reversible.
+    """
+    target = (path or default_registry_path()).resolve()
+    snapshot_path = _revision_path(history_dir(target), revision)
+    if not snapshot_path.exists():
+        available = ", ".join(str(item) for item in list_revisions(target)) or "(none)"
+        raise RegistryValidationError(
+            f"revision {revision} is not retained for {target.name}; available: {available}"
+        )
+
+    payload = json.loads(snapshot_path.read_text(encoding="utf-8"))
+    restored = validate_payload(payload, source_path=target)
+    return save_registry(restored, target)