fix(omp): deliver session-start nudges on every /new session

[dnth]

Intent

Fix: OMP /new omits the once-only session-start nudge on repeat. On OMP 18.1.5, running /new a second time omits the once-only session-start nudge (the FIRSTMATE_OP session-start injection); this was surfaced and reproduced identically during the kunchenguid#3498 watcher-continuity port. Investigate the OMP primary adapter's session-start nudge delivery and its once-only guard (.omp/extensions/fm-primary-omp.ts session_start/session_switch handling plus any nudge-sent marker/state). The nudge MUST fire on each /new session replacement; a stale once-only guard must not suppress it. This is firstmate shared tracked material (.omp/extensions/, bin/, tests, docs) and follows the firstmate-coding-guidelines skill. Reproduce the bug first, fix it minimally, and preserve correct single-fire behavior on an ordinary first session start (do not double-nudge).

Acceptance criteria:

• AC1: The /new-twice nudge omission is reproduced (a documented reproduction or a failing-before/passing-after test).
• AC2: After the fix, the session-start nudge fires on each /new session replacement; the once-only guard no longer suppresses it incorrectly.
• AC3: An ordinary single session start still delivers exactly one nudge (no regression, no double-nudge).
• AC4: A regression test covers the /new-twice case, and the relevant OMP primary/session-start tests plus shellcheck pass.

Decisions made while implementing: the live reproduction showed the omission affects every native /new (not only the second), because after /new the process still owns the session lock, the extension re-arms the watcher immediately, and the watcher's first wake starts an agent-initiated turn via sendMessage(triggerTurn) for which OMP never emits before_agent_start (nor for a captain prompt queued into that turn), so a nudge staged for before_agent_start stays parked. The fix appends the typed session-start instruction to the replacement session's context via omp.sendMessage({customType: firstmate-sessionstart-nudge, display: false, attribution: agent}, {deliverAs: "nextTurn"}) at session_switch time for reasons "new" and "resume", and clears the staged pending nudge so before_agent_start cannot deliver it a second time. Ordinary session_start deliberately keeps the before_agent_start binding to the launch prompt (once-only, no watcher armed yet at process start). /fork and reload switches deliberately still run the wrapper, which stays silent while this process holds the lock. The in-process regression in tests/fm-omp-primary.test.sh drives /new, a second /new with no before_agent_start in between, /resume, and a silent /fork, and fails against the pre-fix adapter (8 of 13 cases) and passes after (13 of 13). The opt-in live guard tests/fm-omp-primary-live-e2e.test.sh now drives two consecutive /new switches and requires each new session's nudge entry to precede its first assistant record; it passed against installed OMP 18.1.5 and that dated result replaces the prior "intentionally red" note in docs/verification/supervision.md. docs/sessionstart-nudge.md and docs/supervision-protocols/omp.md describe the new OMP switch transport. bin/fm-lint.sh and bin/fm-doc-audience-check.sh pass.

Firstmate-Validation-Generation: 284a367c4a91a84a4d86a24a70125e68

What Changed

• Updated the OMP primary adapter to append the session-start nudge to replacement-session context for native /new and /resume switches, clearing staged delivery to prevent duplicates.
• Expanded in-process and live OMP regression coverage for consecutive /new sessions, ordinary startup, /resume, and silent /fork behavior.
• Updated OMP session-start and supervision documentation with the new transport and OMP 18.1.5 verification evidence.

Risk Assessment

✅ Low: The change is narrowly scoped to OMP native session replacement nudge delivery, preserves ordinary startup behavior, and adds behavioral regression coverage and updated verification evidence.

Testing

Exercised the focused OMP primary regression suite, the installed OMP 18.1.5 live lifecycle with two consecutive /new switches, and session-start nudge tests. The regression confirms each replacement receives one nudge while ordinary startup remains single-fire; live E2E completed successfully. No source or transient worktree artifacts were created.

Evidence: OMP primary regression output

ok - OMP /new /resume /fork and reload session_switch paths auto-arm and carry an in-flight actionable close
ok - OMP unacknowledged wake delivery keeps the successor chain and delivers once per close

Evidence: Live OMP 18.1.5 end-to-end output

ok - OMP omp/18.1.5 primary E2E proved fresh no-state and ordinary native discovery, exact ownership, once-only startup, guarded watcher startup, repeated /new continuity, shutdown, resume, and away-mode delivery
ok - OMP omp/18.1.5 primary E2E proved watcher delivery with an intact editable draft

Pipeline

Updates from git push no-mistakes

✅ **intent** - passed

✅ No issues found.

✅ **Rebase** - passed

✅ No issues found.

✅ **Review** - passed

✅ No issues found.

✅ **Test** - passed

✅ No issues found.

• timeout 120 tests/fm-omp-primary.test.sh
• FM_OMP_PRIMARY_LIVE_E2E=1 tests/fm-omp-primary-live-e2e.test.sh
• tests/fm-sessionstart-nudge.test.sh

✅ **Document** - passed

✅ No issues found.

✅ **Lint** - passed

✅ No issues found.

✅ **Push** - passed

✅ No issues found.