fix(mcp): invalidate review session state on cross-profile activation (Closes #690)

A mid-run profile switch (reviewer -> author -> reviewer) left workflow-load
proof, reviewer lease binding, the review decision lock, live namespace
health, and preflight identity/capability stamps intact, so a formal verdict
could be recorded under contaminated session state.

- gitea_activate_profile now invalidates all review-critical session state
  on a cross-profile switch, in memory and in durable state keyed by either
  profile identity, and reports the invalidation + re-preflight requirement.
- Full reviewer preflight (whoami, load_review_workflow,
  resolve_task_capability(review_pr), head re-pin, lease re-acquire) is
  required before any formal verdict after a switch; switching back cannot
  resurrect the stale run.
- Namespace provenance: optional launcher-declared GITEA_MCP_NAMESPACE is
  reported by whoami/runtime context/capability resolution, and a declared
  namespace that disagrees with a task's required namespace fails closed.
- Docs: supported pattern is separate session/namespace per role, not
  in-process profile hopping mid-review.

docs/gitea-execution-profiles.md

@@ -589,6 +589,47 @@ When dynamic profile switching is enabled and a profile is activated via `gitea_
 2. Call `gitea_whoami` with the target remote to prove and verify the fresh Gitea authenticated identity.
 This guarantees the active profile operations align with the actual Gitea authenticated user credential.
 
+### 4. Review-State Invalidation on Profile Switch (#690)
+
+A cross-profile activation (e.g. reviewer → author → reviewer) is a session
+boundary for formal review state. On any switch where the activated profile
+differs from the previous one, `gitea_activate_profile` invalidates, in
+memory **and** in durable session state (for both the old and new profile
+identities):
+
+- preflight identity/capability stamps (`gitea_whoami` / `gitea_resolve_task_capability` proof),
+- review workflow-load proof (`gitea_load_review_workflow`),
+- the review decision lock (including `final_review_decision_ready` markers),
+- the reviewer PR session lease binding,
+- live namespace-health assessments.
+
+Before any formal verdict (`gitea_mark_final_review_decision` /
+`gitea_submit_pr_review`) the full reviewer preflight must be re-established
+under the new profile: `gitea_whoami`, `gitea_load_review_workflow`,
+`gitea_resolve_task_capability(review_pr)`, live head re-pin, and lease
+re-acquire/adopt. Switching back to the earlier profile does **not**
+resurrect the prior run — durable state keyed by either profile identity is
+cleared at switch time.
+
+The supported pattern remains **separate session/namespace per role**
+(dual-namespace, §2): file author-side follow-ups from an author session,
+not by hopping profiles inside a formal review run. Runtime profile
+switching is the operator-approved exception and always carries the
+re-preflight cost above.
+
+### 5. Namespace Provenance (#690)
+
+The server cannot derive its own client-managed MCP namespace name, so a
+launcher may declare it via the `GITEA_MCP_NAMESPACE` environment variable
+(e.g. `gitea-reviewer`). `gitea_whoami`, `gitea_get_runtime_context`, and
+`gitea_resolve_task_capability` report `namespace_provenance` — the
+configured client namespace, the active execution profile, and, for tasks
+with a required namespace (`review_pr` → `gitea-reviewer`, `merge_pr` →
+`gitea-merger`), a mismatch verdict. A declared namespace that disagrees
+with the requested task's required namespace **fails closed**. An
+undeclared namespace is reported as `unknown` and is never treated as
+proof either way.
+
 ## Gitea MCP Runtime Isolation and Worktree Safety
 
 To ensure high availability and prevent broken feature worktrees from disabling essential security/identity controls, the Gitea MCP server implements runtime isolation:

docs/mcp-namespace-health.md

@@ -86,3 +86,24 @@ When a namespace returns EOF, follow
 
 When blocked, repair the IDE namespace and re-record a healthy
 `client_namespace` assessment before retrying the mutation.
+
+## Namespace provenance (#690)
+
+A server process cannot derive the name of the client-managed namespace it is
+registered under, so the launcher may declare it with the
+`GITEA_MCP_NAMESPACE` environment variable (e.g. `GITEA_MCP_NAMESPACE=gitea-reviewer`).
+
+- `gitea_whoami`, `gitea_get_runtime_context`, and
+  `gitea_resolve_task_capability` report `namespace_provenance`: the declared
+  client namespace, the active execution profile, and — for tasks with a
+  required namespace (`review_pr`/`submit_review` → `gitea-reviewer`,
+  `merge_pr` → `gitea-merger`) — a `mismatch` verdict.
+- A declared namespace that disagrees with the requested task's required
+  namespace **fails closed** (`allowed_in_current_session=false` with a STOP
+  guidance entry).
+- An undeclared namespace is reported as `namespace_source="unknown"` and is
+  never treated as proof either way.
+- A profile switch via `gitea_activate_profile` clears all recorded live
+  namespace-health assessments; re-probe through the client before further
+  review/merge mutations.
+