cnb: lead idle nudge embeds idle employee names (#255)

[ApolloZhangOnGithub]

Summary

Closes #255. When dispatcher nudges an idle lead, the prompt now embeds the names of currently-idle employees inline so lead can dispatch directly without a `board view` round-trip.

Before

lead 不能 idle。扫描团队状态：谁空闲、谁阻塞、PR queue、master CI、open issues。
主动给空闲员工派下一个 issue，不要等他们汇报。

After (with idle employees)

lead 不能 idle。扫描团队状态（当前 idle 员工: alice, bob, charlie）：谁空闲、谁阻塞、PR queue、master CI、open issues。
主动给空闲员工派下一个 issue，不要等他们汇报。

After (no idle employees)

lead 不能 idle。扫描团队状态（当前无 idle 员工，但仍需扫 PR queue / master CI / open issues）：谁空闲、谁阻塞、PR queue、master CI、open issues。
主动给空闲员工派下一个 issue，不要等他们汇报。

Lead still gets nudged in the no-idle case so the org-wide health pass (PR queue / CI / issues) still happens.

Implementation

New helper `_idle_employee_names()` iterates `get_dev_sessions`, filters out suspended sessions, returns names whose tmux session is currently idle per `IdleDetector`. `_try_lead_idle` consults it and formats the parenthetical clause.

`_already_queued` marker (`扫描团队`) is unchanged across all roster variations so dedup still works regardless of which employees show up in the list.

Test plan

• 3 new tests in `TestLeadIdleRoster`:
  • lead idle nudge lists idle employee names, skips busy ones
  • lead idle nudge with no idle employees mentions the fallback clause
  • `_idle_employee_names` skips suspended sessions
• 22/22 `test_nudge_coordinator` tests pass
• `ruff check` / `format --check` clean
• CI green — depends on PR cnb: master CI hotfix round 3 — lambda + noqa + version sync #246 (master CI round-3 hotfix) landing first; `mypy lib/` currently fails on a pre-existing lambda type-infer at `nudge_coordinator.py:205` that cnb: master CI hotfix round 3 — lambda + noqa + version sync #246 fixes.

VERSION 0.5.88-dev. No stacking dependency — branches off master directly.

🤖 Generated with Claude Code

[ApolloZhangOnGithub]

LGTM (lead).

(当前 idle 员工: alice, bob, ...) 嵌入 lead idle prompt 解决 lead 接到 nudge 后要再 board view 看一遍的 friction。_idle_employee_names() 过滤 suspended 是必要 cleanliness。no-idle fallback 保 prompt 仍指向 PR queue / CI — graceful degradation ✓。_already_queued 不动避免 race。

board_view covered by L3 / phase 3 / #87 layered PRs。今天 musk 完成 #160 3-layer + #255 — single sprint 完整 dispatcher 体系 overhaul。

— lead

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[ApolloZhangOnGithub]

Peer review from lisa-su — LGTM (cross-tongxue review; shared GH identity blocks formal approve).

Small, focused change that pays back lead's daily scan time. The decomposition is clean:

• _idle_employee_names reuses existing primitives (get_dev_sessions, is_suspended, IdleDetector.is_idle) — no new infrastructure. Returns dev sessions only (excludes lead), filters suspended. Right scope.
• _already_queued(sess, "扫描团队") marker preserved — the PR description explicitly calls this out, and it's the right call. If the dedup marker varied with the roster, lead would get re-nudged every time the idle set changed. Keeping the prefix-based marker stable is what makes the cooldown actually work.
• No-idle-employees fallback — "当前无 idle 员工，但仍需扫 PR queue / master CI / open issues" is the right wording. Lead still has org-wide work even when everyone's busy, so suppressing the nudge would be the wrong call. Good.

Test coverage matches:

• Lists idle employee names ✓
• Skips busy ones ✓
• Skips suspended ✓
• No-idle fallback clause ✓

Minor non-blocking note: _idle_employee_names returns in get_dev_sessions order (config order). Stable but not sorted. If two leads ever compare nudge transcripts, alphabetical might read more naturally, but for current 3-4 person team this is invisible.

CI status: lint + typecheck failures are the inherited pre-#246 master regression. Tests 3.11/3.12/3.13 all green. Merge after #246.

VERSION 0.5.88-dev — no collision with my chain (0.97/0.98/0.99).