VDD Phase 0: Generate constitution.md at the project root — the immutable tech stack, conventions, security constraints, naming rules, and banned patterns that every later phase obeys. Overwrites any existing constitution.md. Run this first, before vdd_vision; to change a constitution that already exists, use vdd_amend instead of re-running this. projectRoot sets the directory constitution.md is written to and that later phases resolve every vdd/ artifact against (default "."). Parameter relationships: projectRoot defaults to "." and must be the same root every later phase resolves against.

VDD Phase 1: Expand a freeform vision statement into vdd/vision.md — Impact Model (Goal, Actors, Impacts), Stakeholder Map, Success Metrics (leading + lagging), Constraints & Boundaries, and Target Domains. Overwrites any existing vdd/vision.md. Requires statement (freeform 1-3 paragraph intent, not a title) and a prior vdd_init. Run once, after vdd_init and before vdd_strategize; to revise a vision once downstream artifacts exist, use vdd_amend so the change cascades instead of re-running this. Parameter relationships: statement must be freeform prose (1-3 paragraphs), not a title; projectRoot must match the root used by vdd_init.

VDD Phase 2: Produce research-backed strategy into vdd/strategy.md — strategic pillars, competitive analysis, and a risk register, resolved from the vision target-domain primers. Overwrites vdd/strategy.md. Requires vdd/vision.md; run after vdd_vision and before vdd_tactics. Two-pass: call once with availableTools to get the research-subagent dispatch specs, then re-call with researchFindings to synthesize strategy.md (a first call with neither returns only the dispatch specs). To change strategy after artifacts exist, use vdd_amend. Parameter relationships: availableTools and capabilities are aliases (pass one); researchFindings only has an effect on the second call.

VDD Phase 3: Audit the existing codebase into vdd/tactics.md — repo audit, technical-debt assessment, gap analysis, MoSCoW-prioritized action items (A-001, A-002, …), dependency map, and infrastructure requirements. Overwrites vdd/tactics.md. Requires vdd/strategy.md; run after vdd_strategize and before vdd_specify. Needs a filesystem-capable host to scan the repo, so check with vdd_detect_environment first if the host may lack one. Parameter relationships: projectRoot must match the root used by vdd_init, vdd_vision, and vdd_strategize; requires vdd/strategy.md to exist.

VDD Phase 4: Generate vdd/specs//spec.md for one tactical action item — user stories, Always/Ask/Never boundaries, Given/When/Then acceptance criteria (AC), MoSCoW priorities, non-functional requirements, and impact verification. Overwrites the spec file. Pass actionItemId (e.g. "A-001") or a freeform description to skip the V/S/T chain. Use for a NEW spec; to resolve leftover [NEEDS CLARIFICATION] markers in an existing spec use vdd_clarify instead. Parameter relationships: feature names the vdd/specs// directory and must match the feature passed to vdd_clarify, vdd_plan, and vdd_tasks; actionItemId is the A-### id from tactics.md and is optional when authoring from a freeform description.

VDD Phase 4b: Clarify an existing spec — scans vdd/specs//spec.md and returns the items to resolve: every [NEEDS CLARIFICATION] marker, [e.g.] placeholder, and happy-path acceptance criterion (AC) still needing an edge-case counterpart (AC-E*). Read-only; returns the list without editing the file (the host agent then applies the resolutions). Pass feature (spec directory name). Run after vdd_specify when a spec has unresolved markers; to author a brand-new spec use vdd_specify instead. Parameter relationships: feature must be the exact spec directory name created by vdd_specify.

VDD Phase 5: Generate the technical blueprint under vdd/specs// — plan.md (component breakdown, AC coverage map, technology choices, verification toolchain), data-model.md (entities, indexes, migrations), and contracts/ (request/response/error schemas). Overwrites these files. Requires an existing spec for the feature; run after vdd_specify or vdd_clarify and before vdd_tasks — if no spec exists yet, run vdd_specify first. Parameter relationships: feature must match the value passed to vdd_specify and vdd_tasks.

VDD Phase 6: Break the plan into atomic test-first tasks in vdd/specs//tasks.md — each references acceptance criteria (AC) and contracts, is sized S/M/L, and is marked [P] when parallelizable. Overwrites tasks.md. Requires plan.md; run after vdd_plan. To fetch the next uncompleted task from an existing tasks.md use vdd_get_next_task instead of re-running this. Parameter relationships: feature must match the value passed to vdd_plan.

VDD Phase 7a: Read vdd/specs//tasks.md and return the next uncompleted task (or a completion marker when none remain). Read-only; never edits tasks.md. Pass feature (the exact spec directory name). Use before each implementation session to keep context isolated; to regenerate the whole list use vdd_tasks, and to execute the returned task use vdd_implement. Parameter relationships: feature must match the spec directory; the returned taskId (TASK-###) is the argument to vdd_implement.

VDD Phase 7b: Prepare one task for implementation — loads constitution, spec, plan, and contracts and returns the implementation instruction plus the impact-chain commit-message format. Read-only; the tool writes nothing — the host agent performs the code edits, verification, and commit. Pass taskId (e.g. "TASK-003") from the task returned by vdd_get_next_task. Run one task at a time, after vdd_get_next_task; for read-only inspection of tasks use vdd_get_next_task instead. Parameter relationships: taskId comes from vdd_get_next_task (format TASK-###); projectRoot must match the root used by earlier phases.

VDD Phase 8: Validate the full chain — bidirectional traceability matrix, drift detection, orphan detection, uncovered vision goals, impact metrics vs targets, and 28 S&T assumption checks across 7 gates. Writes vdd/impact-report.generated.md and never overwrites a hand-authored vdd/impact-report.md. Run after implementation is complete; for the traceability matrix or per-feature spec metrics use vdd_inspect. Parameter relationships: feature narrows the check to one spec; artifactFiles maps artifact path to content for serverless runs and is omitted when resolving against a local projectRoot.

VDD Cross-phase: Read-only inspection of the current project in one call — scope selects the view. scope="project" (default) returns the bidirectional V→S→T→SP→PL→TK traceability matrix across all vdd/ artifacts; scope="feature" returns per-feature spec metrics (acceptance-criteria count, unresolved [NEEDS CLARIFICATION] markers, [e.g.] placeholder density, and whether plan.md/tasks.md exist). Never modifies files. Pass feature for the feature scope; for release-readiness validation with gates use vdd_validate, and to author a spec use vdd_specify. Output is a structured matrix/metrics object, not prose. Parameter relationships: scope="feature" requires feature, while scope="project" (the default) ignores it; projectRoot must match the root used by earlier phases.

VDD Cross-phase: Plan a requirement-change cascade through the whole chain — identifies the highest affected level and returns the ordered steps to update downward V→S→T→SP→PL→TK and re-run affected gates (G1–G7). Read-only; returns the cascade plan without editing artifacts (the host agent applies the edits and commits). Pass the change as description. Use when a requirement changes after artifacts already exist; to build a phase from scratch the first time, run that phase's own tool instead of vdd_amend. The plan is an ordered step list naming the affected gates, not rewritten artifacts. Parameter relationships: description is the requirement change to cascade through the artifact chain; projectRoot must match the root used by earlier phases.

Crawl and capture a target domain into a clone dataset + manifest — WordPress-aware schema inference, Payload collections, and a Next.js + Payload + Postgres scaffold manifest (vdd/clone-manifest.json). Pass the domain as description. Writes vdd/clone-dataset.json, vdd/clone-manifest.json, and vdd/clone.md, overwriting any existing versions in place. Open-world: makes network requests to the target site and reads its sitemap and same-origin links. Use for cloning an external site; it is not part of the VDD phase pipeline, so for the normal init→validate flow call those phase tools instead. Parameter relationships: description is the target domain and statement is the desired outcome (both optional); maxPages, timeoutMs, concurrency, crawl, and browser tune the crawl and refresh=true bypasses a cached dataset.

VDD Environment Detection: Report which tools/MCPs each VDD phase requires vs treats as optional — across the 8-phase pipeline (init through validate) plus the cross-phase helpers (amend, clone, inspect, get-next-task) — and which of the host agent availableTools are present vs missing. Read-only; returns a capability report without modifying files. Run before vdd_strategize to plan research-subagent dispatch, or when a phase fails for lack of a tool; to inspect artifacts instead of capabilities use vdd_inspect. Returns a fixed-shape capability report; tool-name matching is normalized, so pass names as your host exposes them. Parameter relationships: availableTools and capabilities are aliases; omit both to get the per-phase requirements without a present/missing comparison.