handoff-routing

Agent Selection

User Request	Agent	Shortcut Allowed
New feature or enhancement	product-requirements-expert (a root elicitation precedes the dispatch when the intent needs discussion)	No — full pipeline required
Discuss or explore feature idea	root — converse per agentic-harness.md § Conversations Stay in Root; dispatch product-requirements-expert to record the outcome	Yes — one recording dispatch after the conversation
Requirement clarification	root — same elicitation; product-requirements-expert records the PRD change	Yes — one recording dispatch after the conversation
Architecture question	root — same elicitation; system-design-expert records durable-memory changes	Yes — one recording dispatch after the conversation
Bug fix (known cause)	feature-implementer	Yes — skip PRD/design
Code review request	All reviewers in the roster	Yes — parallel invocation

Skip agents for: git operations, answering questions, running one-off commands, summarizing an already-completed change. Formal review of a completed change routes to the reviewers in the roster per the table above.

Handoff Conditions

All transitions are gated on the latest record per (req_id, type) in .scratch/handoff.jsonl. The Handoff Conditions table is executable: python3 scripts/handoff.py route evaluates it and prints one JSON decision. The table itself, the gates' field checks, and the recovery steps live in route-spec.md — the normative spec route executes and scripts/test_handoff.py pins rule by rule. No consumer re-derives it: root runs route after each dispatch returns and follows its decision.

Three decisions exist. dispatch names the next agent(s), the matched rule, and the prompt context. A failed gate is a dispatch of the upstream agent carrying the exact errors — the bounce, expressed as the re-dispatch it is. Root assembles each recovery dispatch's prompt from the section its rule maps to: reviewer-stall-retry from § Reviewer Stall Check; build-retry from route-spec.md § Build-Failure Recovery; truncation-continue from route-spec.md § Truncation Recovery, read on demand. blocked always halts for a human: a dirty log, a conflicting verdict, a stalled reviewer, a human-consultation, feature-complete. escalate marks a state the table does not decide; the pipeline-coordinator is dispatched only on escalate and for untriaged fresh-intake classification. Route is fail-closed: it never repairs a log and never guesses past a failed check. A process-findings decision with halt_after: true carries an escalate finding — root halts after that dispatch per § Blocking.

The escalate arm covers the judgment states: no active slice, refactor-first sibling ordering, truncation of an agent with no recovery row, an autofix-only findings round (autofix-only-round), and any state matching no table row. Both refactor-first log shapes escalate; refactor-resume then re-triages the original deterministically. A no-active-slice escalate on a pick the next skill already triaged is pre-resolved: root dispatches product-requirements-expert directly, skipping the coordinator.

Validation Gates

Each transition validates the inbound record(s) against a schema before dispatching the next specialist; malformed or missing records bounce back to the upstream agent without consuming a downstream dispatch. The gates are structural — required fields, types, patterns — and every check catches deterministically. route enforces them; the per-gate field checks are route-spec.md § Validation Gates. Content quality (are the acceptance criteria good?) is the consuming agent's judgement; cross-record consistency beyond req_id linkage is a consumer finding, not a gate check.

Gate	Transition	Record	Schema
1	product-requirements-expert → system-design-expert	prd-entry	prd-entry.schema.json
2	system-design-expert → implementer	design-block	design-block.schema.json
2b	consultation roundtrip (either direction)	consultation-request / consultation-response	consultation-request.schema.json, consultation-response.schema.json
3	implementer → reviewers	build-pass	build-pass.schema.json
5	build-pass → reviewers (roster resolution)	review-plan	review-plan.schema.json
4	reviewers → next step	review-feedback, one per pass-roster reviewer	review-feedback.schema.json

Gate 2b routes a consultation-response back to the requesting specialist, never forward (§ Mid-Implementation Consultation). Gate 5 resolves the pass roster from the review-plan the implementer appends at gate-pass. A low/high plan gates on its roster; a gray plan dispatches the review-planner to resolve it; a missing or invalid plan fails closed to the full battery (route-spec.md § Gate 5). Gate 4 then waits on that resolved roster — the four-reviewer floor plus declared extras is the default and the fail-closed fallback, defined in review-workflow § Review Phase. The feature is complete when every pass-roster reviewer is approved and every reviewer dispatched since the latest design-block holds a latest approved (route-spec.md § Gate 5). The change-grader is then dispatched (terminal, advisory; skipped when layout.toml [harness] auto_grade = false). On any changes_requested or blocked, findings split by artifact owner (the review-workflow skill's reference.md § Artifact Ownership) — except design-doc autofixes, which root applies per § Root-Applied Autofix on Design Docs. An escalate-tagged finding halts per § Blocking.

Common Procedure

1. Discover. Run Glob .scratch/**/* to enumerate state files. Then Read .scratch/handoff.jsonl only if it appears in the Glob result. Do not Read directories.
2. Gate. If handoff.jsonl is missing or empty when a record is required, the gate fails — route back to the upstream agent.
3. Filter. Records by req_id and type. The latest record for each (req_id, type) is the active state.
4. Check. Required fields, types, and pattern constraints per the schema.
5. Decide. If every check passes: dispatch the next agent. If any check fails: bounce upstream — route emits a dispatch of the producing agent carrying the errors; the coordinator names the failed check in a Blocked recommendation.

Blocking

If any gate fails, if a design-block record carries verdict: "conflicting", or if a review-feedback record carries a tag: "escalate" finding, stop the pipeline and resolve before continuing. For an escalate finding, the halt follows the findings-processing dispatch that records the entry in .scratch/escalations.md (Gate 4). On an approved verdict no findings-processing runs — root appends the entry before halting. route enforces the escalate halt twice: process-findings carries halt_after: true, and escalate-finding-halt blocks re-review until a reviewer record follows the human's decision.

Build-Failure Recovery

A failed quality gate (build error, test failure, format/lint failure) ends the implementer dispatch with a build-failure record carrying the error output and retry count. Schema: schemas/scratch/build-failure.schema.json. route executes the recovery deterministically; route-spec.md § Build-Failure Recovery is the normative definition. The shape:

• An abort_reason short-circuits the retry counter: wrong-shape-slice → product-requirements-expert for re-split; design-mismatch (also a failed autofix audit) → system-design-expert for re-triage; prerequisite-missing → halt for the human. The record shape and trigger live in tdd-workflow § Wrong-Shape Slice Abort.
• Otherwise retry < 3 re-dispatches the implementer with the error trail; retry == 3 re-triages via system-design-expert, whose superseding design-block resets the counter. build-failure records count only after the latest design-block; python3 scripts/handoff.py next-retry --req-id <id> implements the rule.

Truncation Recovery

A feature-implementer dispatch that ends without a build-pass or build-failure for the active req_id truncated before the quality gate. Truncation alone does not mean the slice is over-scoped: the Scoping Pre-Check re-scopes a multi-behavior slice before dispatch. A slice that reaches dispatch and then truncates is presumed correctly sized and simply long. The default recovery is to continue the same slice — up to 3 consecutive truncations, then re-triage via system-design-expert (non-convergence). Re-split is reserved for the Pre-Check's over-size branch and for non-convergence — and even there it is one outcome, not the first response. route executes the steps; route-spec.md § Truncation Recovery is the normative definition. It also defines the two partial-record paths (build-failure with partial: true; review-feedback carrying a truncation finding), which route through existing recovery instead.

Dispatch Truncation Detection

Every dispatched project-defined agent except pipeline-coordinator and the terminal change-grader appends a dispatch-start record as its first tool call. Schema: schemas/scratch/dispatch-start.schema.json. Detection is deterministic and reads .scratch/handoff.jsonl alone:

A dispatch-start record for (req_id, author) with no subsequent substantive record from the same (req_id, author) after that dispatch-start's line signals an interrupted dispatch. A pending consultation-request closes the dispatch for detection; it routes as a consultation instead.

Substantive records (closed enum): build-pass, build-failure, review-feedback, review-plan, prd-entry, design-block, consultation-response. Built-in agents not defined under .claude/agents/ (e.g. general-purpose, Explore) are out of scope for this contract; root carries the dispatch-discipline for those per CLAUDE.md § Tool-call budget.

Mid-Implementation Consultation

The feature-implementer may need a focused answer from product-requirements-expert or system-design-expert during TDD cycles when the inner loop discovers a question the triage didn't anticipate. The implementer appends a consultation-request targeting the specialist; route dispatches that specialist in consultation mode (consultation-dispatch); the specialist appends a consultation-response; route returns control to the implementer (consultation-return).

Consultations are substeps, not handoffs. They preserve the implementer's active state — the pipeline advances only when the implementer's own next handoff (build-pass or build-failure) appears.

Consult when another agent owns the answer. When only the human can decide, target the human: a consultation-request with target: "human" halts the pipeline (human-consultation) while root runs the conversation. Root appends the consultation-response (author: "human") and route resumes the requester — the elicitation pause of agentic-harness.md § Conversations Stay in Root. .scratch/escalations.md remains the surface for findings-driven escalations (§ Blocking) and external prerequisites. The test is who can unblock you.

Review Feedback Actions

See the review-workflow skill for feedback tag definitions and the review process. The two root-applied procedures — the reviewer stall check and design-doc autofixes — live below, because root executes them while routing.

Reviewer Stall Check (root)

route owns the detection and the ladder, deterministically: a reviewer with one silent dispatch-start since build-pass earns a single retry (reviewer-stall-retry); a second silent dispatch returns reviewer-stalled (blocked). Root's part is what a script cannot do. On reviewer-stall-retry, re-dispatch the named reviewer with this prompt: "Your previous run returned without appending a review-feedback record to .scratch/handoff.jsonl. Run the review now. Your only deliverable is that record — see Output Protocol in review-workflow." On reviewer-stalled, append an entry to .scratch/escalations.md naming the reviewer and stop — do not proceed to findings processing. Only root re-dispatches; specialists cannot.

Root-Applied Autofix on Design Docs

To keep the system-design-expert quality bar tight while removing ceremony from mechanical fixes, root may apply tag: "autofix" findings on docs/system-design.md and docs/adr/*.md directly — without redispatching system-design-expert. The quality bar lives in the blocked and clarify (with clarify_target: "system-design-expert") paths, which still route to system-design-expert.

The eligibility rules for autofix on design-doc paths live in the document-writing skill's stack overlay, review-checks.md § Autofix on Design-Doc Paths. Doc-reviewer is responsible for never tagging a finding as autofix on these paths unless every condition there holds (the review-workflow skill's reference.md § Root-Applied Autofix Eligibility). This section defines what root does once such a finding exists.

Apply Procedure

1. Validate the finding statically. Confirm: tag == "autofix"; location falls under a design-doc path; fix field is present and is a literal replacement string (not a description). If any check fails, treat the finding as blocked and redispatch system-design-expert instead.
2. Apply via Edit. Use the Edit tool with the literal fix string as new_string. Read the file to obtain the exact old_string. Do not paraphrase or "improve" the fix — root acts as a typewriter for the doc-reviewer's verbatim proposal.
3. Re-check the bounds after the Edit. Confirm the change stays within the autofix allowlist — the conditions in review-checks.md § Autofix on Design-Doc Paths, the same list handoff.py audit-autofix re-validates at gate time. If any check fails, revert (Edit back) and redispatch system-design-expert.
4. Append a design-doc-autofix record to .scratch/handoff.jsonl carrying: the source finding (copied verbatim), the file path, the autofix category (writing-standards or structural), old_content, new_content, lines_changed, chars_changed. Schema: schemas/scratch/design-doc-autofix.schema.json. Append per the handoff-append skill.
5. Append-only discipline. Preserve every prior line in handoff.jsonl verbatim.

Why The Record Matters

• Gate-time re-validation. python3 scripts/handoff.py audit-autofix (the code-quality-gate skill's autofix audit) mechanically re-checks every design-doc-autofix record against the allowlist bounds, so a mis-applied autofix fails the quality gate before merge.
• The system-design-expert audits on next dispatch. The design-validation skill instructs the system-design-expert to read all design-doc-autofix records since its last dispatch and judge them. It may reject any by appending an autofix-rejected finding to the next design-block record.
• Direct-edit detection. The same command fails if docs/system-design.md or docs/adr/* has uncommitted changes that no design-doc-autofix or design-block record covers — catching any future bypass of the protocol.

What Root Does Not Do

• Root does NOT autofix on docs/prd.md (product-requirements-expert owns PRD; no autofix exception).
• Root does NOT autofix any tag other than autofix (blocked/clarify/escalate route as defined elsewhere).
• Root does NOT batch autofixes across artifacts — one record per finding, one Edit per finding.

State Files

File	Created By	Consumed By
.scratch/handoff.jsonl	product-requirements-expert, system-design-expert, feature-implementer, review-planner, the roster reviewers, change-grader, root (all append-only)	the router — route and, on escalate, the coordinator (validation gates); all consumer agents
.scratch/implementation-plan.md	feature-implementer	feature-implementer (self-tracking)
.scratch/escalations.md	feature-implementer (escalate-tag findings, mid-loop escalations); root on the router's blocked decision (prerequisite-missing aborts; reviewer stalls per § Reviewer Stall Check; escalate findings on an approved verdict per § Blocking) — never the coordinator itself	Human

.scratch/handoff.jsonl is the append-only structured handoff log; one JSON object per line, each carrying a type discriminator. Record types:

Record type	Producer	Purpose
prd-entry	product-requirements-expert (system-design-expert: the refactor-first sibling entry)	Active feature scope for system-design-expert and implementer.
design-block	system-design-expert	Triage verdict and implementation guidance.
consultation-request	any specialist mid-work	Focused question to another specialist that does not advance the pipeline.
consultation-response	the consulted specialist	Focused answer; routes control back to the requester.
review-feedback	each reviewer agent in the roster	Per-reviewer verdict and findings.
build-failure	feature-implementer	Quality-gate failure with error context and retry counter.
build-pass	feature-implementer	Quality-gate success marker.
review-plan	score-change.py review-plan (author review-plan-engine); review-planner for the gray zone	Names the reviewer roster and read scope for a review pass; fail-closed to the full battery when absent or invalid.
design-doc-autofix	root	Audit trail for root-applied autofixes on design-doc paths (see § Root-Applied Autofix on Design Docs).
dispatch-start	every project-defined agent except pipeline-coordinator and change-grader (as its first tool call)	Half of the dispatch-event contract; "no subsequent substantive record from same (req_id, author)" is the deterministic truncation signal. Not substantive — does not satisfy the implicit stop.
grader-features	change-grader (score-change.py extract)	change-grader (the grading read). Deterministic structural row; advisory, terminal — does not route.
grader-verdict	change-grader	Advisory facets + rationale + clear/concern verdict; surfaced to the session, recorded, never routed. Not substantive for truncation detection.

Log Access

The coordinator never writes records — it only reads them for routing decisions. All writes to .scratch/handoff.jsonl go through scripts/handoff.py per the handoff-append skill, which holds the writer contract, the full command table, and the exit codes. Reading the whole log with the Read tool for context is fine; decisions that gate routing use the query subcommands below.

Operation	Command
Routing decision	python3 scripts/handoff.py route [--req-id <id>]
Latest record for a gate	python3 scripts/handoff.py latest --type <type> [--req-id <id>]
Next retry counter	python3 scripts/handoff.py next-retry --req-id <id>
Whole-file check	python3 scripts/handoff.py validate

route exits 0 whenever a decision was computed — including blocked and escalate; the decision field carries the state. The human-inspection surface (show, and view via the handoff-board skill) is listed in handoff-append § Writer Commands.

Human Checkpoints

Routing is deterministic: a passed gate names the next agent per the Handoff Conditions table, without waiting for approval. Human attention concentrates at four points — two advisory, two blocking:

1. After PRD update (advisory) — Review that the requirement captures intent. The pipeline proceeds; to intervene, halt and route back to product-requirements-expert to append a superseding prd-entry.
2. After design notes (advisory) — Review the architectural approach. Same intervention path, via system-design-expert.
3. After escalations (blocking) — The pipeline halts until the human decides each [ESCALATE] item. A design-block with verdict: "conflicting" halts the same way (Handoff Conditions table).
4. After feature complete (blocking) — The change-grader's verdict is advisory; only the human approves the merge.

Coordinator Output Format

The coordinator handles what route cannot: untriaged fresh-intake classification and every escalate decision; a next-triaged pick dispatches product-requirements-expert directly. Its recommendation follows the same table; route's JSON is the deterministic fast-path for the rows the table decides alone.

The pipeline coordinator responds with a structured recommendation:

## Pipeline State
[Current state based on .scratch/ files]

## Recommendation
**Action:** Invoke [agent-name]
**Prompt:** "[suggested prompt for the agent]"
**Shortcut:** Yes/No
**Reason:** [why this agent is next]

If blocked:

## Pipeline State
[Current state]

## Blocked
**Blocker:** [description]
**Resolution:** [what needs to happen]

Coordinator Rules

These rules bind the coordinator when it is dispatched — fresh intake and escalate states. On the routine path route applies the same table.

1. Never skip pipeline stages for new features.
2. Shortcuts are allowed only per the agent selection table above.
3. If .scratch/ contains stale state from a previous feature, recommend clearing it first.
4. Report all design-block records with verdict: "conflicting" and all review-feedback findings tagged escalate.
5. Recovery ladders are route's, never yours: build-failure retries (route-spec.md § Build-Failure Recovery) and implementer truncation (§ Truncation Recovery) are decided deterministically. What reaches your escalate arm is their degenerate states — abort-unknown, failure-without-design, truncation-before-design, and a truncated agent with no recovery row. Decide those; never re-decide a ladder rung.
6. After every reviewer dispatched since the latest design-block holds a latest "approved" verdict (route-spec.md § Gate 5), the feature is complete: recommend dispatching the change-grader agent (terminal, advisory). With layout.toml [harness] auto_grade = false, skip that recommendation — route reports feature-complete directly. The grader assesses how much human attention the passing change deserves; its clear/concern verdict is recorded and surfaced to the session, but it does not route and is not a merge or correctness gate. Do not consume its verdict for any routing decision.