Merge origin/master: scope-aware fusion of the tools/execute seam, session-prefix, and tool-cordis

Master brought 50 commits (the tool-cordis group, dsh-code-runtime + worker,
the tools/execute around-dispatch seam + timeout-policy, repeat-tool-guard,
agent/session-prefix, the ui reorganization). Beyond the ten textual
conflicts, the merge reconciles master's new seams with this branch's
scoped-registration world:

- tools/execute (new waterfall around core dispatch): dispatched with the
  SAME exec.agent carrier as the pre/post waterfalls — an agent.ctx wrapper
  times/retries only its own agent's calls — and its base thunk resolves the
  tool through the caller's visible view (get(exec.name, exec.agent)), so a
  scoped/shadowed tool dispatches and a restricted-away global stays
  UNKNOWN_TOOL. Declared this: Scoped<ToolRegistry> with the scope-filtered
  doc sentence; invariants table + verify-scoped-dispatch pin it (21 events).
- agent/session-prefix (new waterfall, once per loop instance): composed via
  the fused agentEvents dispatcher (scope-filtered like every agent-subject
  event), declared this: Scoped<Agent>, table-pinned. agent/pre-step keeps
  master's new sessionPrefix parameter with this branch's Scoped this.
- timeout-policy reads the budget through the caller's visible view
  (get(exec.name, exec.agent)): a scoped tool's own timeoutMs governs its
  calls; a global name-twin's budget is never misapplied to a shadowing
  per-agent variant.
- tool-cordis: cordis_inspect's tools section lists the CALLING agent's view
  (its description promises "what you can call"); the sandbox tool façade's
  reads resolve through the mount's own scope, mirroring where its register
  lands writes; sandboxRegisterTool's return type carries the exact-disposer
  union honestly. dsh-scope declared as peer+dev with the project reference.
- doc-sync chain unions master's verify-cordis-api with this branch's
  verify-scoped-dispatch; the generated catalogs, event matrix (the
  zero-dispatcher guard passes over master's new events), module graph, and
  the cordis api-catalog are regenerated on the merged surface.

Full gate sequence green on the merged tree: typecheck, lint, per-file 100%
coverage (2668 tests), snapshots (38), doc-sync, module graph, build,
hygiene, demo smoke.

packages/support/invariants/tests/invariants.spec.ts

@@ -708,6 +708,21 @@ describe('request-reconstruction cross-check (llm/stream)', () => {
     expect(() => { dispatch(ctx, options) }).not.toThrow()
   })
 
+  it('expects the folded header\'s session prefix ahead of the derivation (prefix + derived)', async () => {
+    const { ctx, session, boundary } = await requestSetup()
+    const prefix = { role: 'user' as const, content: [{ type: 'text' as const, text: '<system-reminder>catalog</system-reminder>' }] }
+    session.append('request/header-delta', { messagePrefix: [prefix] })
+    // The prefixed request matches the fold…
+    const prefixed = Object.freeze({ model: 'm', messages: Object.freeze([prefix, ...boundary]), sessionId: session.id })
+    expect(() => { dispatch(ctx, prefixed) }).not.toThrow()
+    // …a request that DROPPED the logged prefix diverges…
+    const bare = Object.freeze({ model: 'm', messages: Object.freeze([...boundary]), sessionId: session.id })
+    expect(() => { dispatch(ctx, bare) }).toThrow(/diverges from the boundary derivation/)
+    // …and so does one that misplaced it (prefix sent after the history).
+    const misplaced = Object.freeze({ model: 'm', messages: Object.freeze([...boundary, prefix]), sessionId: session.id })
+    expect(() => { dispatch(ctx, misplaced) }).toThrow(/diverges from the boundary derivation/)
+  })
+
   it('rejects a frozen request whose messages diverge from the boundary derivation', async () => {
     const { ctx, session, boundary } = await requestSetup()
     const messages = [...boundary, { role: 'user', content: [{ type: 'text', text: 'phantom' }] }]