RPI Implement

Goal

Deliver the approved outcome using the current task-centered plan as evidence. Keep task completion, implementation evidence, plan maintenance, and validation trustworthy for the caller.

Flow

1. Resolve the exact plan at .copilot-tracking/plans/{{YYYY-MM-DD}}/{{task_slug}}-plan.md and declared invocation scope: the full plan, one Pxx phase, or one Pxx-Txx task. Read each in-scope task's Goals:, Requirements:, Details:, Guidance: when present, References:, and Dependencies: blocks, follow the linked references, and check the plan's decision and risk tables for rows that name the task. The declared scope limits completion claims and active implementation.
2. Create or continue .copilot-tracking/changes/{{YYYY-MM-DD}}/{{task_slug}}-changes.md using templates/changes-log.md. Record material evidence under descriptive headings tied to plan areas or markers, not per-entry formal IDs.
3. Before substantive source edits or implementation, update the plan checklist, changes record, and any related state tracking artifacts.
   • Send the implementation opening defined in references/implementation.md.
4. Start with the first unchecked dependency-ready plan item in declared scope, then execute eligible items in plan order.
   • Survey available skills and subagents whose stable name contains implement or implementation, or whose description explicitly says they are used during implementation, and retain only candidates whose descriptions fit the current task. Exclude this skill and other RPI lifecycle phase entrypoints from helper selection. Activate useful matching skills as scoped implementation guidance.
   • Delegate only a whole Pxx phase when it is in declared scope, dependency-ready, independent, parallelizable, and write-disjoint. Prefer a matching implementation subagent. When none fits, dispatch an unnamed general-purpose subagent by omitting the agent selection. Its prompt must state the implementation purpose, exact phase, dependencies, approved disjoint source-write boundary, validation expectations, and evidence return, and prohibit scope expansion, parent plan, state, and changes-record edits, user decisions, and nested delegation. The primary implementation agent executes individual Pxx-Txx tasks, consumes phase returns, and retains plan order, reconciliation, implementation-time plan updates, and completion markers.
   • When a task's Requirements: hold and its evidence is recorded in the changes record, immediately check the completed Pxx-Txx marker in scope. Check a Pxx phase immediately only when that phase is in scope and every task in the phase is checked. Do not check markers outside declared scope.
5. When declared scope finishes, ensure its changes, blockers, completion markers, remaining work, and validation state are current. Report active plan markers outside the scope as remaining work. Report full-plan completion only when the full plan was declared and all of its markers have completion evidence.
6. Classify new implementation information using references/implementation.md: retain ordinary local judgment, apply immediately relevant current-state updates that preserve approved intent, record unrelated work as follow-up-only, and treat a discovery as material only when it requires a new user decision or planning reconsideration.
   • When completed work creates something a later task needs that the plan does not already name, such as a class, API, contract, helper, fixture, or path, add a Guidance: block immediately after that task's Details: with the concrete pointer. This is an immediately relevant update and needs no user decision.
   • Keep the Phase Checklist diagrams current when a plan update adds, merges, splits, or removes phases or tasks.
7. Ask for the smallest decision-critical user input only when available evidence cannot support a responsible user-owned decision. Persist the result in current planning state and the changes record. If the accepted plan must change, pause only affected dependent work and return the current evidence to planning. The confirmed user decision remains authoritative; do not run another critique.
8. After the approved source or correction batch is complete, run the checks the task's Requirements: or Details: name and whatever validation the changed behavior warrants; the implementer chooses how to verify. Record checks, results, and explicit skip reasons in the changes record without treating validation alone as permission to resume paused dependent work.
9. Before handing a full-plan or review-ready scope to Review, reconcile plan markers and task-local context, completed-work evidence, handoff prose, blockers, remaining work, follow-up items, and validation state.
10. Return the current implementation result to the caller using the return contract below.

Inputs

• Approved plan path or task context
• Optional declared scope: full plan, exact Pxx phase, or exact Pxx-Txx task
• Task-local plan context, supplied evidence, latest critique disposition, and prior changes record when available

Success criteria

• The implementation follows the approved plan or records a material discovery and its current state explicitly.
• The first unchecked dependency-ready item in declared scope starts execution, and later dependent work does not bypass plan order.
• Completed Pxx-Txx tasks are checked immediately after completion evidence exists. A Pxx phase is checked immediately after every task in that in-scope phase has completion evidence.
• A bounded Pxx or Pxx-Txx result confirms only its declared scope and reports remaining active-plan markers without claiming full-plan completion.
• Only a whole declared-scope Pxx phase that is dependency-ready, independent, parallelizable, and write-disjoint may be delegated. The worker is selected by phase-and-task fit or is an unnamed general-purpose fallback with explicit implementation restrictions. It returns expected evidence for primary-agent reconciliation, and individual Pxx-Txx tasks are never delegated.
• The changes record uses descriptive evidence headings and plan or task markers, with no second per-entry identity scheme.
• Implementation discoveries are classified as local judgment, immediately relevant current-state update, follow-up-only work, or material decision, with the detailed record required by the reference.
• A later task that depends on something earlier work created receives a Guidance: block naming it when the plan did not already do so.
• Affected dependent work resumes after the significant or divergent user decision is reflected in the current plan. The task's critique is not repeated.
• Validation evidence or an explicit skip reason is available for changed behavior.
• A later invocation may implement applicable Review findings as ordinary work without a correction run type or mandatory second Review.
• Plan markers and task-local context, changes evidence, handoff prose, blockers, remaining work, follow-up items, and validation state are reconciled before Review.
• The caller receives the current execution status, evidence paths, current plan state, validation coverage, blockers, remaining work, and follow-up items.

Constraints

• Use references/implementation.md for detailed execution evidence, current-state reconciliation, material-discovery handling, questions, resumption, and rendered conversation mechanics.
• Do not expand active scope. Place unrelated work in an explicit follow-up item.
• Do not use line numbers or separate legacy log artifacts.
• In the plan and changes record, wrap code, commands, and symbols in backticks and link existing files and folders with the workspace-relative path as the link text and a path relative to the artifact file as the destination. Keep a not-yet-created path in backticks.
• Keep .copilot-tracking/ references out of production code, code comments, documentation strings, and commit messages.

Conversation guidance

• Follow the detailed opening, continual-update, pre-question, and closeout protocol in references/implementation.md. That reference is the authority for the rendered message templates.
• Persist canonical state before the opening, any material update, decision question, handoff, or closeout. Chat is a concise projection of that state, never a second history or delivery log.
• At closeout, report implementation execution status separately from review readiness. Qualify every status by the declared scope and list remaining active-plan markers so bounded completion is not mistaken for task completion.
• Advise /compact only when stale tool output, superseded reasoning, or completed task detail outweighs useful current context and the plan and changes record are current. When advising it, name the state and artifact pointers to retain. Otherwise omit compaction guidance.
• In a standalone invocation, do not invoke rpi-review. State /rpi-review only when review prerequisites are met. In an active rpi-quick or confirmed automatic RPI Agent context, return current artifacts and scope facts to the parent for eligible continuation.
• For every relevant existing artifact, use the two-cell row | [actual/workspace-relative/path.ext](https://github.com/microsoft/hve-core/blob/main/.github/skills/rpi/rpi-implement/actual/workspace-relative/path.ext) | Short description |, using that artifact's actual workspace-relative path as both link text and destination; omit unavailable files and render the table immediately before the final ## Next Steps section. End with ## Next Steps: state the exact eligible user command, active-parent action, blocker-clearing action, or that no user action is required. When compaction is warranted, tell the user to run /compact before the next RPI command; otherwise omit compaction guidance.

Stop rules

• Stop as Blocked when the approved plan, required details, or a dependency prevents credible execution.
• Stop as Blocked when a decision-critical user answer needed for a major plan change, blocker, or workaround is unavailable.
• Pause affected dependent work only when a significant or divergent decision changes assessed requirements, scope, architecture, dependency model, or evidence boundary. Return current artifacts to planning when needed, preserve the existing critique as historical evidence, and resume after the user decision and plan state are current.
• Stop after a caller-bounded Pxx phase or Pxx-Txx task once its declared-scope plan state and changes evidence are current. Do not require or imply completion of work outside that scope.

Return to Caller

Return the changes-record path, implementation execution status, completed and remaining Pxx or Pxx-Txx items, validation coverage, blockers, current plan updates, follow-up items, and review readiness or the explicit reason affected work awaits a user decision. Follow the Conversation guidance section for standalone or parent-orchestrated continuation, conditional compaction advice, the linked artifact table, and final next steps.