writing-plans

Authoritative format boundary

For a new full-lane HTML spec, load {{PLUGIN_ROOT}}/includes/artifacts.md and use the installed structured-artifact engine for every spec and plan read or write. The resulting pair is .codearbiter/specs/<slug>.html and .codearbiter/plans/<slug>.html. Missing or invalid HTML capability is a STOP before writing and must not fall back to Markdown. An existing authoritative Markdown spec continues through the legacy Markdown path without conversion. HTML --farm dispatch remains blocked.

Turn an approved spec into an executable plan, or prepare a ready draft plan for initial combined HTML sprint review. Draft preparation is not execution authority. Routed to by /feature (after spec approval) and /sprint under its explicit call mode.

Pre-flight

Read these, or STOP and surface the gap. Missing specs always block. Ordinary planning requires approval; only initial full-lane HTML sprint-pair preparation accepts an exact ready draft:

• The authoritative approved spec selected by /feature: for HTML, resolve it through the installed engine and verify its ready approval and exact identity; for legacy Markdown, read {{PROJECT_DIR}}/.codearbiter/specs/<slug>.md. Absent → STOP. Unapproved → STOP except the explicit initial sprint draft_for_pair mode, which verifies ready/current draft identity through the private preflight and never grants execution. Route a genuine missing prerequisite back to the active caller, not an unrelated feature interview.
• {{PROJECT_DIR}}/.codearbiter/CONTEXT.md — the stage: frontmatter (the maturity value) and project context.
• {{PROJECT_DIR}}/.codearbiter/tech-stack.md — file layout, build/test/lint invocations. A verification step cites a real command from here, never a guess.
• {{PROJECT_DIR}}/.codearbiter/coding-standards.md — structure and naming, so a task names the right path.

If --farm was requested: check that FARM_API_KEY is set in the environment{{IF:pi}} of the Pi parent process{{ELSE}} (or .env at {{PLUGIN_ROOT}}/tools/.env){{END}}. If absent, BLOCK immediately — cite {{PLUGIN_ROOT}}/includes/farm.md for setup instructions. Do not proceed; the farm dispatcher cannot run without an API key. Model selection happens later (at dispatch time in subagent-driven-development), so no model research is needed here.

Phase 1 — Criterion extraction · gate: BLOCK

Lift every acceptance criterion from the spec and retain its stable ID (AC-01, AC-02, …). For HTML, obtain criterion records through typed engine reads and retain their typed IDs; rendered document text is not an authority source. This list is the coverage ledger for the whole plan — Phase 4 checks the task set against it.

A criterion the spec leaves ambiguous is a [CONFIRM-NN] against {{PROJECT_DIR}}/.codearbiter/open-questions.md — surface it, do not invent the intent.

Backstop the ledger against the spec's own stated intent, mechanically, before trusting it — this runs even when brainstorming already ran the same check, because a hole that survived Phase 3 survives Phase 4's bijection too, silently (#566): run "$PY" "{{PLUGIN_ROOT}}/hooks/_intentlib.py" uncovered-intent <spec-path> [--issue-body <scratch-file>], where <spec-path> is the authoritative .html or legacy .md spec selected above — <scratch-file> holds the linked issue's body when one exists (gh issue view <N> --json body -q .body > <scratch-file>, written outside the working tree), omitted when none does. A non-empty result names an in-scope bullet or an acceptance checkbox the criteria never cited — BLOCK and route back to brainstorming ({{PLUGIN_ROOT}}/skills/brainstorming/SKILL.md) to add the missing criterion or record a [CONFIRM-NN]; never paper over a missing criterion by authoring a task for it here instead. This is the LAST point before a hole gets laundered through Phase 4's bijection, which only checks the ledger against itself and cannot see past it.

Then ask the half this tool cannot mechanize: if every AC-NN passed and nothing else changed, what would still be broken? A real answer names a criterion the ledger is missing even though every scope bullet and checkbox is technically cited — judgment, not mechanizable, and not satisfied by a rhetorical "nothing." Finding nothing broken is a reportable result, stated in one line, never a silent skip.

Gate: every acceptance criterion in the spec captured as a numbered AC-NN; the uncovered_intent backstop above returns empty or every finding is resolved; and the negative question has been asked and answered. A partial ledger does not pass.

Phase 2 — Task decomposition · gate: BLOCK

Break the work into the smallest honest units. Each task is ~2–5 minutes of work and carries:

• id — T-01, T-02, … stable.
• path(s) — the exact file(s) the task touches, resolved against coding-standards.md. "Some files" is not a path.
• verification — one concrete command or observable that proves the task done (e.g., <test cmd> -k test_token_expiry passes, endpoint returns 401 on missing header). It cites a real tech-stack.md invocation or a directly observable behavior — never "looks right".
• maps-to — the tdd obligation this verification corresponds to. The verification maps to a tdd obligation; it does NOT replace tdd's own gates. tdd Phase 1 still derives and Phase 4 still verifies obligations against passing tests.
• covers — the AC-NN(s) this task advances.

Split anything that won't fit ~5 minutes or touches unrelated paths. Reject the trap of one monolithic "implement the feature" task — that defeats the plan.

Gate: every task has at least one path AND a verification AND a maps-to. A task missing any of the three blocks the plan.

Phase 3 — Order & MVP slice · gate: BLOCK

Order tasks so each runs only after what it depends on. Flag every dependency explicitly (T-07 depends on T-03). A cycle is a decomposition error — return to Phase 2 and split.

Group the ordered tasks so the MVP slice is identifiable: the minimal contiguous task set that satisfies the spec's core acceptance criteria and is shippable on its own. Everything past the slice is incremental.

Gate: a complete dependency order with no cycle, and an explicitly marked MVP slice.

Phase 4 — Bijection proof & write · gate: BLOCK

Cross the ledger against the task set, both directions. This proves the plan and the ledger AGREE with each other — it does not prove the ledger itself is COMPLETE relative to the spec's stated intent. A criterion missing from the ledger entirely was never a candidate for either check below; that completeness gap is caught earlier, by Phase 1's uncovered_intent backstop (and by brainstorming Phase 3 before that) — never re-derived here, and never implied by this phase's name (#566: a prior version of this gate read "coverage proof", which a bijective check does not earn).

• Every AC-NN is covered by at least one task's covers. An uncovered criterion blocks — author the missing task.
• Every task advances at least one AC-NN. A task that covers nothing is scope creep — cut it or surface it.

For an HTML source, pass the selected route, installed client, and the spec identity just read from the engine through _preflight_plan_authoring. Initial full-lane sprint pair preparation alone sets draft_for_pair: true; the ordinary default still requires approval. Only its returned same-slug .codearbiter/plans/<slug>.html target may be created. Create that plan through the installed structured-artifact engine as draft_preview, using the source spec's exact artifact ID and normative digest. For ordinary sequential planning, this must be the approved spec's exact artifact ID and normative digest. Populate it only with typed operations and validate it at the ready gate. Before presenting either ordinary or combined review, call the private _approvallib._preflight_plan_verification(client, identity) with the current engine identity. It reads every task through bounded engine pages, checks each declared runner's supported named-outcome format, snapshots current inputs, and rejects identity drift. Resolve the complete reported set of command/input diagnostics before asking for approval. It does not run commands, discover or import tests, or require proposed test files and test names to exist. Input roots must already exist: choose an existing containing directory for files the plan will create. Roots and excluded directories are exact repository-relative paths, not basenames, globs, or paths relative to each root; for root site, use site/node_modules, site/dist, and other reviewed output paths. The ordinary and paired approval adapters repeat this preflight before arming their user reply. This admission check is not verification evidence; execution still binds actual commands and requires current named outcomes. For initial combined review, retain draft_preview and return both ready identities to the caller: sprint-approve owns the binding and both approvals after one actual host-observed reply. Do not separately plan-bind or approve that pair. On ordinary approved-spec planning, use plan-bind to bind it to the approved spec before plan approval. This path must not create .codearbiter/plans/<slug>.md; that would be a shadow authority.

For an existing authoritative Markdown source, write {{PROJECT_DIR}}/.codearbiter/plans/<slug>.md — <slug> matching the spec — with the AC-NN ledger, the ordered task table (id · path(s) · verification · maps-to · covers · depends-on · status, initialized PENDING), the marked MVP slice, and any out-of-scope item tagged inline [NEEDS-TRIAGE].

The status column is the pipeline's resume ledger: subagent-driven-development flips a task to ACCEPTED the moment it accepts it, so an interrupted run (crash, compaction, closed session) is re-entered by /feature at the first non-ACCEPTED task instead of restarted from brainstorming.

Gate: bijection proven between the plan and the ledger — no criterion without a task, no task without a criterion — and the plan written to disk. This proves the two are mutually consistent, nothing more; completeness of the ledger itself was Phase 1's gate, not this one. Initial combined-review drafts return for arm-sprint, never execution. Only verified approved spec-and-plan authority clears execution: executing-plans (checkpointed, via /feature) or subagent-driven-development (autonomous, via /sprint) — each routes every task through tdd. The plan never hands off to tdd directly.

Phase 4-farm extension (only when --farm was requested)

When --farm was requested for a legacy Markdown workflow, after the bijective coverage gate passes and the .md plan is written, produce the farm artifact (plan.json) — one MVP slice at a time — per {{PLUGIN_ROOT}}/skills/writing-plans/references/farm-plan.md. Load that leaf and follow it; it owns the per-task failing-test + schema-valid plan.json procedure.

Gate: all failing tests written and confirmed failing; plan.json written and schema-valid. Both artifacts exist before handing off to subagent-driven-development ({{PLUGIN_ROOT}}/skills/subagent-driven-development/SKILL.md).

Hard rules

• MUST NOT execute or approve work against an absent or unapproved spec. Only explicit initial full-lane HTML draft_for_pair planning accepts a ready draft and must return for combined approval; other unapproved inputs route back to their actual caller.
• MUST NOT write or parse rendered HTML directly, create a Markdown shadow for an HTML spec, or bind a plan from a caller-supplied identity.
• MUST NOT emit a task without an exact path AND a concrete verification step.
• MUST NOT let a task's verification stand in for a tdd gate — it maps to a tdd obligation, it does not replace one.
• MUST NOT write the plan while any acceptance criterion is uncovered or any task covers nothing.
• MUST NOT guess a verification command — cite tech-stack.md or STOP.
• MUST NOT resolve an ambiguous criterion by guessing — raise a [CONFIRM-NN].
• MUST run the uncovered_intent backstop and ask the negative-judgment question in Phase 1, and MUST NOT treat Phase 4's bijection proof as a substitute — bijection proves the plan and the ledger agree with each other, never that the ledger is complete (#566).
• MUST NOT emit plan.json in --farm mode without writing and confirming each failing test first.
• MUST NOT set meta.model or meta.apiBaseUrl in plan.json — these belong to the dispatch step.
• MUST NOT proceed with --farm if FARM_API_KEY is absent — cite {{PLUGIN_ROOT}}/includes/farm.md and BLOCK.
• MUST, at exit, run the follow-up harvest ({{PLUGIN_ROOT}}/includes/harvest.md) over any [NEEDS-TRIAGE] out-of-scope items — batch-confirm promoting them to open-tasks.md (work) or open-questions.md (decisions) so they don't die in the plan file.