codex-sdd:implement

OpenSpec Implement

Context

Implement is the third phase of the OpenSpec workflow. It executes the tasks from tasks.md one by one, tracking progress and updating the state machine. This is the "execute with discipline" step.

Trigger

Any of these patterns triggers this skill:

• User says "openspec implement" or "openspec:implement"
• User says "start implementation" or "execute tasks"
• openspec_get_status shows phase is implement
• openspec_get_status shows phase is plan with design confirmed

Prerequisites

• An approved openspec/changes/<changeId>/design.md for full preset changes
• A generated openspec/changes/<changeId>/tasks.md with tasks listed
• User has confirmed readiness to implement

Workflow

Step 1: Read Tasks

Call openspec_read_artifact({ artifactId: "tasks" }) to understand the full task list and identify incomplete tasks.

Step 2: Check Status

Call openspec_get_status to confirm the project is in the implement phase.

Step 3: Execute Next Task

Work through tasks one at a time:

1. Find the first incomplete task (marked [ ] in tasks.md)
2. Read design, specs, and implementation_notes artifacts when present
3. Implement the required code changes
4. Run focused verification for the task
5. Call openspec_record_validation_evidence with the check result
6. Call openspec_record_iteration with changed files, commands, test results, errors, and evidence references
7. After implementation is done, ask user to verify the change when the task has medium/high risk, external side effects, or ambiguous acceptance criteria
8. Call openspec_update_task({ taskId: "T1", done: true }) only after passed evidence exists or the user explicitly approves pending validation
9. Repeat for the next incomplete task

Step 4: Validation Checkpoints

After each task, provide a brief summary:

• What was implemented
• Related files changed
• Any notable decisions or deviations from the design

Gate: Destructive Changes — Auto-pause and ask before:

• Deleting or renaming files
• Changing public API signatures
• Modifying database schemas
• Large refactors affecting existing tests
• Writing to external systems
• Security-sensitive or permission-sensitive changes
• Flag these in the summary and ask for confirmation before proceeding with openspec_request_human_review.