C4 follow-up: re-record manager fixture post-C4, strip bash leftover from SOP, document remaining asks as C4-followup proposal

Closes review asks from cross-review of C4:

- Jobs ask #2: team-building.en.md still referenced the bash+fetch
  pattern for goal creation. Rewritten as a deferred-tool note pointing
  to C5 follow-up, without re-teaching the HTTP shape C4 just removed.

- Karpathy ask #1 (partial): re-recorded manager-task-handoff against
  main to produce post-C4 positive evidence. VP Engineering has
  hire_agent available via canRequestHire, but when directed NOT to
  hire, the recorded trace shows task decomposition only (no
  hire_agent invocation). 455 in / 769 out tokens; assertions updated
  to pin /api/task/create + agent_ic_ slugs + p99 substring + max 3
  turns. The `non-ceo-dm-reply` re-record is deferred to the follow-up
  ticket.

- Karpathy asks #2, #3, #4 + Jobs asks #1, #3, #4: documented in
  docs/proposals/C4-followup.md with concrete completion criteria.
  Scope covers canFileCeoStrategy predicate, non-ceo-dm-reply
  re-record, RFC 8594 Deprecation/Sunset headers + counter, and a
  negative substring assertion kind for the eval harness.

Eval still green at 8/8. C4 main batch (e2c839b..8e99e01) stands
unchanged; this commit is pure follow-up groundwork.

docs/proposals/C4-followup.md

@@ -0,0 +1,69 @@
+# Proposal C4-followup: close out the remaining taste debt from C4
+
+> Source: Roundtable 2026-04-20 session 6 cross-review (Jobs + Karpathy request_changes asks)
+> Prerequisite: C4 landed (commits c91a233 through 0a35acf)
+> Owner: TBD
+> Estimated effort: 1-2 working days
+> Blocking dependencies: none — safe to pick up any time
+
+## What this proposal closes out
+
+C4 shipped the main meat — `hire_agent` + `file_approval` internal tools, the CEO initial-user-turn downgrade, the team-building SOP rewrite, and HTTP-hire deprecation. Cross-review surfaced four follow-up items that were out of scope for the C4 session but are small enough to land in a single follow-up pass. They are grouped here so a future session can execute them as one unit.
+
+## Item 1: tighten `canRequestHire` scope to match the C4 narrative
+
+**Problem** (Karpathy review, specific ask #2): `src/main/orchestration/internal-tool-selector.ts` attaches `hire_agent` to any agent where `canRequestHire` returns true. In `src/main/database/agent-permissions.ts:91-103`, `canRequestHire` is true whenever the role or title matches `vp|director|manager|lead|head|chief|cto|cmo|coo|cfo` or the agent sits in the HR department. The C4 commit narrative claims "CEO-only injection" — the code does not match.
+
+**Fix**: introduce a separate `canFileCeoStrategy(agent)` predicate (true only when `reportsTo === null` AND role is CEO-equivalent). Attach `file_approval` only when that predicate holds. Leave `hire_agent` attached on `canRequestHire` but update the C4 commit narrative and team-building.en.md to say so explicitly. A manager hiring an IC is a legitimate flow — the original "CEO-only" framing was narrower than reality.
+
+**Verification**: a fixture showing a manager (non-CEO) invoking `hire_agent` during a team-expansion trigger would pin the broader scope as intentional.
+
+## Item 2: re-record `non-ceo-dm-reply` post-C4 for positive evidence
+
+**Problem** (Karpathy review, specific ask #1): `tests/eval/fixtures/non-ceo-dm-reply.jsonl` was recorded at commit `302b8a0` before C4 part 3/5 (tool injection at `79edff5`) landed. The fixture therefore cannot discriminate between "non-CEO correctly does not receive `hire_agent` in its tool schema" and "the tool was never offered because part 3/5 had not merged yet." `manager-task-handoff` was re-recorded post-C4 already (see `c4-followup-manager-rerecord` commit in this proposal's implementation). `non-ceo-dm-reply` still needs the same treatment.
+
+**Fix**: re-record `non-ceo-dm-reply` with the current main tree. Confirm the assistant response still covers `mark_read` and `/api/agent_message/send` calls without referencing `hire_agent` (VP Product with two IC reports has management authority → `canRequestHire` is true → the tool is technically attached, but the trigger is a peer DM so the tool should not be invoked).
+
+**Verification**: `pnpm test:eval --run` stays green with existing assertions.
+
+## Item 3: add a deprecation counter and `Deprecation:` header to legacy HTTP hire routes
+
+**Problem** (Karpathy specific ask #3, Jobs specific ask #1): `routes-agents.ts` and `routes-approvals.ts` currently emit a single `log.warn("[deprecated][C4] ...")` line per call. That's enough for audit-by-grep, insufficient for asserting "usage has hit zero" before physical removal.
+
+**Fix**:
+1. Expose a counter via the existing telemetry module (if one exists; grep for `metrics.increment` in `src/main/`). Tick on every call.
+2. Add RFC 8594 HTTP headers to the deprecated routes:
+   - `Deprecation: true`
+   - `Sunset: Wed, 20 May 2026 00:00:00 GMT` (or a date 30 days out from the follow-up commit)
+   - `Link: <docs/proposals/C4-followup.md>; rel="deprecation"`
+3. Document removal timeline: if the counter stays at zero for two weeks after this proposal lands, delete the route handlers physically.
+
+## Item 4: negative assertion kind for the eval harness
+
+**Problem** (Karpathy specific ask #4): the current `assertion-judge.ts` supports positive substring assertions (`message_contains_substring`) but no negation. Asserting "the IC fixture does NOT contain `hire_agent` in its tool list" is not expressible, so tool-schema regressions on the IC path are only caught implicitly.
+
+**Fix**: add a new assertion kind in `tests/eval/assertion-judge.ts`:
+
+```ts
+type Assertion =
+  | ... // existing kinds
+  | { kind: "message_does_not_contain_substring"; role: "user" | "assistant"; substring: string };
+```
+
+Wire it through `assertion-judge.ts`'s `evaluate` switch. Update `tests/eval/harness.self-test.ts` (or wherever the harness self-tests live) to cover the new kind positively and negatively. Update C4-followup fixtures to use it where appropriate.
+
+## Non-goals
+
+- This proposal does NOT expose goal creation as an internal tool — that is C5-scope (`expose remaining CEO primitives as tools`) and depends on goal-lifecycle design.
+- This proposal does NOT delete the legacy HTTP routes — they stay until the counter from item 3 stays at zero for two weeks.
+- This proposal does NOT add an LLM-as-judge tier — that is B5.1-scope and gated on fixture count N ≥ 10.
+
+## Completion criteria
+
+This proposal closes when all four items land and:
+- `pnpm typecheck` green
+- `pnpm test:eval --run` green at ≥ 8/8
+- `canFileCeoStrategy` predicate exists and is referenced by `internal-tool-selector.ts`
+- `non-ceo-dm-reply` fixture's `recordedAt` is after `c91a233`
+- Deprecation counter exists; counter value visible in telemetry; RFC 8594 headers on both legacy routes
+- `message_does_not_contain_substring` assertion kind passes harness self-tests