coord driver: make wave rollover and housekeeping a deterministic state machine #2127

Observed during a live drive-board-normal run on 2026-08-02. The host correctly dispatched six workers but later waited with only two active items instead of applying the declared consolidation-threshold=3, reconsolidating, and immediately starting wave two. The operator had to remind the host of the rule. The same run also exposed adjacent memory-sensitive transitions: reconcile --apply initially failed because the host had no worker identity; a critic posted a substantively correct but syntactically invalid review marker; stale-claim reaping, flush, fresh lint/backlog triage, engine-currency checks, and dispatch eligibility were separate manual steps. A worker also returned terminal output multiple times while its claim was still live, tests were still running, and no review-ready SHA existed; the host had to reactivate it manually.

The root cause is that the driver is documented as a state machine but executed as prose from agent memory. batch already emits activeItems, waveCapacity, and openSlots; the engine should own the transition logic and receipts that follow from those facts. Agents should provide judgement (classification, consolidation objective, review findings), not remember deterministic ordering.

Acceptance

1. Add an fsgg-coord driver planning/advance surface that reads live claims and board state and emits one typed next action for the two-wave model: continue current waves, consolidate at activeItems <= 3, run housekeeping, repair engine currency, or dispatch a sized next wave.
2. A dispatch receipt is refused unless it is bound to a fresh successful chain: reconcile dry-run, mechanical apply where needed, flush with zero pending writes, fresh reconcile, fresh lint/backlog inventory, and scoped engine-currency zero. Stale receipts fail closed.
3. The engine counts claimed, in-review, and newly dispatched items across both waves, reserves two critic slots, and proves the 6 -> 2 regression starts a new three-slot wave after housekeeping rather than waiting.
4. Mechanical housekeeping owns or explicitly requests a host identity before writes; it cannot partially apply and then present the pass as complete.
5. Review-chain validation is machine-checkable: required marker spelling, critic identity, exact SHA, ordered rounds, round ceiling, check state, and host-acceptance readiness are returned as typed data. An unmarked prose review is rejected.
6. Stale-claim reaping and engine-currency repair are first-class transition gates, with receipts naming what changed and whether dispatch is now legal.
7. Committed tests reproduce this run: low-occupancy rollover, stale claim, missing host identity, invalid review marker, pending write, stale engine, and no-dispatch-before-fresh-triage.
8. Human judgement remains explicit inputs: defect/hardening/decision classification and whether overlapping objectives consolidate are not automated.
9. A worker return is not counted terminal while its claim remains live and the item is neither review-ready nor parked/Done; the planner emits a typed resume-same-worker action and tests the live-claim/no-PR and live-claim/tests-running cases.

Class: hardening

Paths: .agents/skills/drive-board/** .claude/skills/drive-board/** .agents/skills/drive-board-normal/SKILL.md .claude/skills/drive-board-normal/SKILL.md .agents/skills/work-board/** .claude/skills/work-board/** .agents/skills/work-board-normal/SKILL.md .claude/skills/work-board-normal/SKILL.md .agents/skills/pnext-item/references/independent-review.md .claude/skills/pnext-item/references/independent-review.md .fsgg/** work/2127-driver-transition-state-machine/** readiness/2127-driver-transition-state-machine/** AGENTS.md CLAUDE.md TestResults/coord-core.trx src/FS.GG.Kit/FS.GG.Kit.csproj src/FS.GG.Coord.Core/Driver.fs src/FS.GG.Coord.Core/Driver.fsi src/FS.GG.Coord.Core/FS.GG.Coord.Core.fsproj src/FS.GG.Coord.Cli/Client.fs src/FS.GG.Coord.Cli/Options.fs src/FS.GG.Coord.Cli/Options.fsi src/FS.GG.Coord.Cli/Program.fs src/FS.GG.Coord.GitHub/Reads.fs src/FS.GG.Coord.GitHub/Reads.fsi tests/FS.GG.Coord.Core.Tests/DriverTests.fs tests/FS.GG.Coord.Core.Tests/FS.GG.Coord.Core.Tests.fsproj tests/FS.GG.Coord.Cli.Tests/ApplicationServiceTests.fs tests/FS.GG.Coord.Cli.Tests/CommandSurfaceTests.fs tests/FS.GG.Coord.Cli.Tests/DriverCommandTests.fs tests/FS.GG.Coord.Cli.Tests/FS.GG.Coord.Cli.Tests.fsproj tests/FS.GG.Coord.Cli.Tests/OptionsTests.fs registry/driver-skill-manifest.json scripts/fsgg-coord-guards.sh tests/coord-engine-e2e/writes.sh

Evidence: this run missed the documented fsgg:wave-model:v1 ... consolidation-threshold=3 transition until operator correction; reconcile --apply then refused without a host identity; the first #1176 critic comment omitted <!-- fsgg:independent-review:v1 --> and required correction before repair could legally route; #1181 returned terminal output repeatedly before its active claim reached review handoff.