Implementation Plan

Act as a senior/staff engineer designing a low-risk implementation plan for the active engineering task.

Goal: Create an incremental, reviewable, production-safe implementation plan for the active task, then persist it in the task repository as explicit, reviewable updates (avoid silent replanning when nothing material changed).

Mandatory context bootstrap (before any output):

• Read these sections in WORKFLOW_OPERATING_SYSTEM.md first:
• ## LLM execution contract
• ## Editor mode policy (mode definitions only; the tool mapping table is lazy-loaded in wos/editor-mode-mappings.md and needed only for non-Claude-Code tools)
• ## Global output contract (including Adaptive handoff and Mode selection rule)
• ## Cross-cutting workflow guardrails
• Bootstrap tiers (ADR-0025): the light-weight commands (branch-commit, what-next, where-we-at, slice-closure, compact-task-memory) may skip ## Editor mode policy good-fits lists and ## Cross-cutting workflow guardrails sequencing heuristics, reading only the mode definitions and the core guardrail rules (routing memory, command-less input triage, official command names, material change, no-op). This reduces bootstrap from ~6,750 to ~3,500 tokens for these commands.
• Read additional sections only when relevant to this command's role.
• Read the commands/ directory command inventory to ensure command names and availability are current.
• Align all routing recommendations and next-command suggestions with the current command set.
• Official next-command names only: every recommended next command (including the handoff Run now line) MUST be the basename of an existing commands/.md file in this workflow repository. Never invent names.

Required inputs:

• active task folder path
• TASK_STATE.md
• SOURCEOFTRUTH.md
• DECISIONS.md
• IMPACT_ANALYSIS.md, if available
• INVARIANTSANDNON_GOALS.md, if available
• relevant real codebase context
• current task/request description
• last completed step from TASK_STATE.md (command + summary)
• any "relevant prior lessons" surfaced by task-init from prior LEARNINGS (read-only; let them inform slice shaping and risk notes, per ADR-0017)
• optional: --spec to a spec, PRD, or requirements document (internal to the repo or already captured) to derive the plan from that spec and check coverage of every spec item, per ADR-0061 (see the spec-ingest mode in Operating rules)

Operating rules:

• Do not write code.
• Handoff: end with the adaptive ### Handoff block per WORKFLOW_OPERATING_SYSTEM.md ## Global output contract (Mode A compact or Mode B full).
• Substrate write protocol (per ADR-0034, K.2; emission duty per ADR-0101). MANDATORY for EVERY H2 section this run writes to IMPLEMENTATION_PLAN.md (per commands/_shared/substrate-write-protocol.md ## When to emit), not only the owned subset. Ownership per wos/substrate-peers.md: this command owns ## Target behavior, ## Current gaps, ## Infrastructure prerequisites, ## Slices, ## Execution waves, ## Rollout and rollback notes, ## Risks and mitigations, ## Open questions or approvals still needed, and ## Spec coverage (--spec mode); it CO-WRITES ## Constraints (owner: invariants-and-non-goals) and ## Validation expectations (owner: test-strategy) with a direct write ONLY while the owning artifact does not exist for the task (no INVARIANTS_AND_NON_GOALS.md, no TEST_STRATEGY.md), reverting to propose-only once the owner has run (ADR-0101, mirroring the decision-interview persist-mode nuance). Per commands/_shared/substrate-write-protocol.md ## Concrete computation (bash scripts/emit-substrate-write.sh is the invokable path):

1. Compute sha_before via the canonical sha_of_section bash helper (or null only if the section did not exist prior to this write).
2. Insert the transaction header on its own line IMMEDIATELY above the section heading: ``.
3. Write or update the section content.
4. Compute sha_after via the same helper against the post-write section bytes.
5. Append exactly one JSON line to active//.wos/VERIFICATION_LOG.jsonl per the 12-field schema in wos/substrate-peers.md ## Audit trail. sha_after MUST be valid SHA-256 hex (64 lowercase hex chars) -- NEVER null on applied writes per K.5 validator. sha_before is null ONLY on first write to a fresh section.
6. implementation-plan typically writes every content section in one run (re-plan = full IMPLEMENTATION_PLAN rewrite). Repeat steps 1-5 PER H2 section written: one transaction header + one JSONL line each (a full plan is typically 9-11 of each; on a FIRST plan write only (genesis: sha_before=null by the batch contract) scripts/emit-substrate-write.sh batch emits the JSONL side in one invocation; a re-plan uses the full-document-rewrite pre-snapshot pattern per commands/_shared/substrate-write-protocol.md ## Full-document rewrite). Reuse the same run_id + ts across all section writes. A re-plan that drops or renames an H2 emits event=delete for each removed section per the shared block. Per-slice status mutations by implement-approved-slice / slice-closure follow their OWN K.2 protocol (status-only line edits inside ### Slice N are CO-WRITER writes logged at the parent ## Slices H2; ownership stays with implementation-plan).

FORBIDDEN: half-compliant pattern (JSONL emitted but inline header omitted, OR sha_* null on existing sections). K.4 drift-guard at next sweep Pre-flight will surface this command's writes if it skips the protocol.

• Never truncate before Handoff: even after a long IMPLEMENTATION_PLAN.md payload inside ### Artifact changes, the message must still end with ### Handoff and the fenced standard ending format.
• Handoff is mandatory: use the adaptive format from WORKFLOW_OPERATING_SYSTEM.md ## Global output contract. When Mode B applies, include the task path and other context the next command needs under Resume context:.
• Design-surface routing (site dogfood F1, ADR-0099). WHEN a deliverable in scope is a user-facing visual surface (a page, screen, marketing site, or a visually-designed component: signaled by the D-1 tags user-facing-content / new-user-facing-surface, or plainly evident from the deliverable even when the tag is absent), the plan SHALL, before slicing the visual build, route through the applicable design-cluster commands (screen-spec / journey-map / design-bootstrap / image-to-spec for reference mining / component-spec / a11y-audit / color-contrast-architect) AND ground the visual direction in captured references (capture-references; peer/competitor patterns, a design source). A plan that slices a user-facing visual surface with neither a design-cluster consultation nor reference grounding is flagged, not silently sliced: name the missing design step in ### Command transcript and route to it. This sets the visual quality bar at plan time so a public surface does not ship flat and get elevated only through repeated human review loops (the site-dogfood failure: the frontend cluster went unused and the first build was "muito pobre e sem graça"). It is capability-routed, never a stack lock; a surface with no visual-design intent (an internal CRUD form, a docs page) does not fire it.
• No code changes should happen before plan approval.
• Before producing output, verify implementation-plan is still the highest-value command based on TASK_STATE.md and whether the plan would materially change.
• If IMPLEMENTATION_PLAN.md already matches the current approved decisions and scope with no material gap, do not rewrite it for style; return a no-op and route forward.
• No-op rule for artifacts:
• If IMPLEMENTATION_PLAN.md would not materially change, do not rewrite it.
• If TASK_STATE.md would not materially change, do not rewrite it.
• Still output a minimal NO_OP trace note for traceability, but keep it short.
• Break the work into the smallest safe slices. A single-phase plan covering the whole task is invalid when the work touches more than one file, contract, or behavioral seam; produce explicit numbered slices instead (use SLICES/01_.md, 02_.md, ... when slice-level traceability helps). This enforces the spec Core principle 6 ("Prefer small approved slices over broad implementation").
• Optimize for correctness, low blast radius, and ease of review.
• Do not include opportunistic refactors unless required for safety or correctness.
• Apply the YAGNI restraint ladder to every slice before committing it to the plan: does this need to exist at all, then can the standard library do it, then the native platform, then an already-installed dependency, then a one-line change, then the minimum viable implementation. Flag any slice that adds a dependency or a new abstraction without a DECISIONS.md entry backing it. Tie the floor to DECISIONS.md and INVARIANTS_AND_NON_GOALS.md so safety-required structure is never trimmed away. (implement-approved-slice and review-hard enforce the same restraint at execution and review.)
• For each phase or slice, define:
• objective
• exact scope
• Scope: the explicit file paths or globs this slice creates or modifies (machine-readable, one path per entry). Consumed by implement-fleet to compute parallelizable waves; an under-declared scope defeats the ADR-0041 file-scope disjointness gate, so list every file the slice will touch.
• Depends-on: the slice IDs this slice requires, or none (machine-readable). With Scope, this defines the slice DAG.
• Deliverable-tag: WHEN a slice's deliverable is user-facing product content or a new user-facing surface, the slice SHALL carry Deliverable-tag: user-facing-content or Deliverable-tag: new-user-facing-surface (ADR-0091); the closure floors key off this tag, and an untagged content deliverable is caught by the closing floor's backstop and flagged. Omit for slices with no user-facing deliverable. Derive the tag by reading the ## Requested deliverables ledger in TASK_STATE.md first: every ledger row tagged user-facing-content or new-user-facing-surface SHALL have its covering slice(s) carry the matching tag; dropping a ledger-carried tag is flagged in ### Command transcript and blocks at approve-plan's consistency gate (ADR-0103). Tagging test (ADR-0103, extending ADR-0091): the tag applies when a human end user experiences the content or reaches the surface through ANY client, visual or not (an MCP prompt surface reached via chat tags; an MCP tool whose RESULT a human end user consumes in the client tags; a tool or API consumed only by the model or another machine does not); machine-to-machine APIs and developer-facing CLIs do not tag.
• Decision-ref: the DECISIONS.md D-N entry (or entries) this slice implements, or none with a one-line reason. Optional but preferred: approve-plan's consistency gate reads it when present and falls back to content-level tracing otherwise (ADR-0103); a task with no locked decisions passes that gate without this field.
• Status: initialized planned; values planned | approved | implemented (pending closure) | closed; mutated only by implement-approved-slice / slice-closure per the K.2 co-writer rule.
• why this order is safe
• key risks
• validation approach
• exit criteria -- MUST use EARS template (per ADR-0031). Event-driven form preferred for slices: WHEN the SHALL . Banned softeners in canonical sentence: should, may, appropriate, sensible, reasonable. Free-form prose for rationale is OK; the canonical sentence must use SHALL keyword.
• work complexity for executing that slice: exactly one of LOW, MEDIUM, HIGH (definitions in WORKFLOW_OPERATING_SYSTEM.md), plus one line why (no model names)
• asset-fidelity decision (design-to-code slices only, per ADR-0051): Asset-fidelity: real-MCP (the slice pulls the exact Figma node before editing) or Asset-fidelity: placeholder (with a one-line reason and the approval). Omit for non-design slices; when a slice implements from a design source and nothing is stated, the default is real-MCP and the execution gate enforces it.
• optional STOP conditions: for Disciplined or Strict-tier and boundary slices, the observable signals that mean the executor must halt and escalate rather than improvise (scope creep beyond the declared Scope, a failing test the slice did not introduce, an unexpected schema or contract touch). Omit for simple slices; do not over-specify, since false halts add ceremony.
• Explicitly identify:
• what must change
• what must not change
• what remains uncertain
• Include rollout and rollback notes when runtime behavior is affected.
• If planning cannot proceed safely due to unresolved ambiguity, stop and recommend the correct prior command instead.
• If the plan would introduce new behavioral commitments not supported by DECISIONS.md and evidence, label them as PROPOSED and route to the smallest decisive upstream command (targeted-questions, decision-interview, resolve-contract-gaps, or contract-signoff) instead of pretending they are already decided.
• Retrofit mode (annotate-only; the adoption bridge for implement-fleet per ADR-0041). When the caller signals retrofit or annotate-only (asks to make an existing plan fleet-ready, or arrives here from implement-fleet Step 1 because slices lack Scope / Depends-on) and a valid IMPLEMENTATION_PLAN.md already exists:
• Do NOT re-derive the plan or change any slice's intent, objective, or ordering. This mode only backfills structured fields and computes waves; it is not a re-plan.
• Read TASK_STATE.md to determine which slices are already executed. Annotate and wave-compute over the REMAINING (not-yet-executed) slices only.
• For each remaining slice, infer Scope (the files it will touch, grounded in the slice's prose scope plus a read of the real codebase, never guessed) and Depends-on (from the stated ordering and from shared files). Tag any scope the model is unsure of with a one-line (inferred; verify) note so the user can correct it before dispatch; an under-declared scope defeats the ADR-0041 disjointness gate.
• Compute the Execution waves over the remaining slices and state the parallelizability verdict: which waves have size >= 2 (where implement-fleet helps) versus a pure chain (where it does not).
• Persist the annotation as a PROPOSED delta to the existing ## Slices section (the section this command already owns); do not rewrite unchanged slice content.
• Handoff routes to implement-fleet when at least one remaining wave has size >= 2, otherwise to implement-approved-slice for the next slice.
• NO_OP when every remaining slice already declares Scope and Depends-on and the Execution waves are current.
• Spec-ingest mode (--spec , per ADR-0061). When the caller passes --spec (a spec, PRD, or requirements document), derive the plan FROM the spec instead of from a free-form task description:
• Read the spec in full. Enumerate every named feature, requirement, or acceptance item as a discrete spec item. Keep the spec's own wording as the item label so coverage stays auditable; do not paraphrase an item away.
• Map each spec item to one or more slices. The mapping is many-to-many but TOTAL: every spec item MUST trace to at least one slice ID. A slice may cover several small items; a large item may span several slices.
• Run the deliverable-coverage check (ADR-0056): seed or extend the ## Requested deliverables ledger in TASK_STATE.md with one row per spec item (tagged in-scope), then assert each row maps to a slice. A spec item with no slice is a silent omission: surface it in the canonical three-field marker form `[NEEDS CLARIFICATION: spec item "" maps to no slice | include it as a slice or de-scope it | add a covering slice, or record a de-scope in DECISIONS

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Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: Mozurok
• Source: Mozurok/fhorja.dev
• License: MIT
• Homepage: https://fhorja.dev

Install and usage instructions live in the source repository linked above.