Nix Implementation Skill

Thin wrapper that delegates Nix configuration implementation to nix-implementation-agent subagent.

Trigger Conditions

This skill activates when:

• Task type is "nix"
• /implement command targets a Nix task
• NixOS modules, Home Manager configs, or flake changes need to be created using Nix

Execution Flow

Stage 1: Input Validation

Validate task_number exists, task_type is "nix", and an implementation plan is present.

Stage 2: Preflight Status Update

Update status to "implementing" BEFORE invoking subagent.

Stage 3: Prepare Delegation Context

Domain-specific context for the nix-implementation-agent:

• Nix style guide from .claude/extensions/nix/context/
• MCP-NixOS for package/option validation (when available)
• Verification: nix flake check, nixos-rebuild build --flake .#hostname

{
  "session_id": "sess_{timestamp}_{random}",
  "delegation_depth": 1,
  "delegation_path": ["orchestrator", "implement", "skill-nix-implementation"],
  "timeout": 7200,
  "task_context": {
    "task_number": N,
    "task_name": "{project_name}",
    "description": "{description}",
    "task_type": "nix"
  },
  "plan_path": "specs/{NNN}_{SLUG}/plans/MM_{short-slug}.md",
  "metadata_file_path": "specs/{NNN}_{SLUG}/.return-meta.json"
}

Stage 4: Invoke Subagent

Use Agent tool with subagent_type: "nix-implementation-agent".

Stage 4b: Self-Execution Fallback

CRITICAL: If you performed the work above WITHOUT using the Agent tool (i.e., you read files, wrote artifacts, or updated metadata directly instead of spawning a subagent), you MUST write a .return-meta.json file now before proceeding to postflight. Use the schema from return-metadata-file.md with the appropriate status value for this operation.

If you DID use the Agent tool, skip this stage -- the subagent already wrote the metadata.

Postflight (ALWAYS EXECUTE)

The following stages MUST execute after work is complete, whether the work was done by a subagent or inline (Stage 4b). Do NOT skip these stages for any reason.

Stage 5: Parse Subagent Return

Read the metadata file from specs/{N}_{SLUG}/.return-meta.json.

Stage 6: Update Task Status (Postflight)

Update state.json and TODO.md based on result.

Stage 7: Link Artifacts

Add artifact to state.json with summary. Update TODO.md per @.claude/context/patterns/artifact-linking-todo.md with field_name=**Summary**, next_field=**Description**.

Stage 8: Git Commit

Commit changes with session ID.

Stage 9: Return Brief Summary

MUST NOT (Postflight Boundary)

After the agent returns, this skill MUST NOT:

1. Edit .nix files - All Nix config work is done by agent
2. Run nix flake check - Verification is done by agent
3. Analyze or grep source - Analysis is agent work
4. Write summary/reports - Artifact creation is agent work

PROHIBITION: If the subagent returned partial or failed status, the lead skill MUST NOT attempt to continue, complete, or "fill in" the subagent's work. Report the partial/failed status and let the user re-run /implement to resume.

The postflight phase is LIMITED TO:

• Reading agent metadata file
• Updating state.json via jq
• Updating TODO.md status marker via Edit
• Linking artifacts in state.json
• Git commit
• Cleanup of temp/marker files

Reference: @.claude/context/standards/postflight-tool-restrictions.md

Return Format

Brief text summary (NOT JSON).