| name | skill-implementer |
| description | Execute general implementation tasks following a plan. Invoke for general implementation work. |
| allowed-tools | Agent, AskUserQuestion, Bash, Edit, Read, Write |
Implementer Skill
Thin wrapper that delegates general implementation to general-implementation-agent subagent.
IMPORTANT: This skill implements the skill-internal postflight pattern. After the subagent returns,
this skill handles all postflight operations (status update, artifact linking, git commit) before returning.
This eliminates the "continue" prompt issue between skill return and orchestrator.
Context References
Reference (do not load eagerly):
- Path:
.claude/context/formats/return-metadata-file.md - Metadata file schema
- Path:
.claude/context/patterns/postflight-control.md - Marker file protocol
- Path:
.claude/context/patterns/subagent-continuation-loop.md - Continuation loop pattern
- Path:
.claude/context/patterns/context-exhaustion-detection.md - Context exhaustion heuristics
- Path:
.claude/context/patterns/file-metadata-exchange.md - File I/O helpers
- Path:
.claude/context/patterns/jq-escaping-workarounds.md - jq escaping patterns (Issue #1132)
Note: This skill is a thin wrapper with internal postflight. Context is loaded by the delegated agent.
Trigger Conditions
This skill activates when:
- Task type is "general", "meta", or "markdown"
- /implement command is invoked
- Plan exists and task is ready for implementation
Execution Flow
Stage 1: Input Validation
Validate required inputs:
task_number - Must be provided and exist in state.json
- Task status must allow implementation (planned, implementing, partial)
task_data=$(jq -r --argjson num "$task_number" \
'.active_projects[] | select(.project_number == $num)' \
specs/state.json)
if [ -z "$task_data" ]; then
return error "Task $task_number not found"
fi
task_type=$(echo "$task_data" | jq -r '.task_type // "general"')
status=$(echo "$task_data" | jq -r '.status')
project_name=$(echo "$task_data" | jq -r '.project_name')
description=$(echo "$task_data" | jq -r '.description // ""')
if [ "$status" = "completed" ] || [ "$status" = "abandoned" ] || [ "$status" = "expanded" ]; then
return error "Task is in terminal state [$status]"
fi
Stage 2: Preflight Status Update
Update task status to "implementing" BEFORE invoking subagent.
Run the centralized status update script, which atomically updates state.json, TODO.md (task entry + Task Order), and the plan file:
bash .claude/scripts/update-task-status.sh preflight "$task_number" implement "$session_id"
Note: The script handles all three updates (state.json status/timestamps/session_id, TODO.md [PLANNED] -> [IMPLEMENTING] in both task entry and Task Order, and plan file status -> [IMPLEMENTING]) in a single call. No additional Edit or jq operations are needed.
Stage 3: Create Postflight Marker
Create the marker file to prevent premature termination:
padded_num=$(printf "%03d" "$task_number")
mkdir -p "specs/${padded_num}_${project_name}"
cat > "specs/${padded_num}_${project_name}/.postflight-pending" << EOF
{
"session_id": "${session_id}",
"skill": "skill-implementer",
"task_number": ${task_number},
"operation": "implement",
"reason": "Postflight pending: status update, artifact linking, git commit",
"created": "$(date -u +%Y-%m-%dT%H:%M:%SZ)",
"stop_hook_active": false
}
EOF
Stage 3a: Calculate Artifact Number
Read next_artifact_number from state.json and use (current-1) since summary stays in the same round as research/plan:
next_num=$(jq -r --argjson num "$task_number" \
'.active_projects[] | select(.project_number == $num) | .next_artifact_number // 1' \
specs/state.json)
if [ "$next_num" -le 1 ]; then
artifact_number=1
else
artifact_number=$((next_num - 1))
fi
if [ "$next_num" = "null" ] || [ -z "$next_num" ]; then
padded_num=$(printf "%03d" "$task_number")
count=$(ls "specs/${padded_num}_${project_name}/summaries/"*[0-9][0-9]*.md 2>/dev/null | wc -l)
artifact_number=$((count + 1))
fi
artifact_padded=$(printf "%02d" "$artifact_number")
Note: Implement does NOT increment next_artifact_number. Only research advances the sequence.
Stage 4a: Memory Retrieval (Auto)
Retrieve relevant memories from the memory system to inject into the delegation context.
Skip if: clean_flag is true in the delegation context (from --clean command flag).
if [ "$clean_flag" != "true" ]; then
memory_context=$(bash .claude/scripts/memory-retrieve.sh "$description" "$task_type" "" 2>/dev/null) || memory_context=""
fi
If memory_context is non-empty, it will be injected into the Stage 5 prompt alongside the format specification from Stage 4b. If empty, no memory block is injected.
lit_context=""
if [ "$lit_flag" = "true" ] && [ ! -f "specs/literature-index.json" ]; then
LIT_DIR="${LITERATURE_DIR:-$HOME/Projects/Literature}"
GLOBAL_INDEX="$LIT_DIR/index.json"
if [ ! -f "$GLOBAL_INDEX" ]; then
echo "Note: --lit flag used but no global Literature index found at $GLOBAL_INDEX. Continuing without literature context." >&2
else
:
fi
fi
Stage 4a-fork: Inline population (option "Create task and run now")
When the user selects "Create task and run now", after calling literature-create-setup-task.sh:
-
Invoke the Agent tool with subagent_type: "fork" and a prompt instructing the fork to:
-
After the fork returns, check if specs/literature-index.json was created:
- If yes: run
lit_context=$(bash .claude/scripts/literature-briefing.sh 2>/dev/null) || lit_context=""
- If no (fork failed or timed out): log a warning, report the task number, suggest
/orchestrate N, set lit_context=""
if [ "$lit_flag" = "true" ] && [ -f "specs/literature-index.json" ]; then
lit_context=$(bash .claude/scripts/literature-briefing.sh 2>/dev/null) || lit_context=""
fi
Note: lit_flag is independent of clean_flag. Using --clean --lit suppresses memory retrieval but still injects literature briefing. Literature briefing is gated solely on lit_flag == "true".
Stage 4: Prepare Delegation Context
Prepare delegation context for the subagent:
{
"session_id": "sess_{timestamp}_{random}",
"delegation_depth": 1,
"delegation_path": ["orchestrator", "implement", "skill-implementer"],
"timeout": 7200,
"task_context": {
"task_number": N,
"task_name": "{project_name}",
"description": "{description}",
"task_type": "{task_type}"
},
"artifact_number": "{artifact_number from Stage 3a}",
"effort_flag": "{effort_flag from command, null if not set}",
"model_flag": "{model_flag from command, null if not set}",
"plan_path": "specs/{NNN}_{SLUG}/plans/MM_{short-slug}.md",
"metadata_file_path": "specs/{NNN}_{SLUG}/.return-meta.json"
}
Note: The artifact_number field tells the agent which sequence number to use for artifact naming (e.g., 01, 02). Summary uses the same round number as the research and plan that preceded it.
Model/Effort Flags: If model_flag is set (haiku, sonnet, opus), pass it as the model parameter on the Agent tool to override the agent's frontmatter default. If effort_flag is set (fast, hard), include it as prompt context for reasoning depth guidance.
CRITICAL: No Source Reading Before Delegation -- Between preparing the delegation context (Stage 4) and spawning the sub-agent (Stage 5), the lead skill MUST NOT read, grep, glob, or analyze source files. The plan file and state.json are the only files the lead reads. All codebase exploration (reading source files, grepping for patterns, using MCP tools) is the exclusive responsibility of the sub-agent after it is spawned.
Stage 4b: Read and Inject Format Specification
Read the summary format file and prepare it for injection into the subagent prompt. This ensures the subagent always has the full format specification in its context, regardless of whether it reads the file itself.
format_content=$(cat .claude/context/formats/summary-format.md)
The format content will be included as a delimited section in the Stage 5 prompt (see below).
Stage 5: Invoke Subagent
CRITICAL: You MUST use the Agent tool to spawn the subagent.
Required Tool Invocation:
Tool: Agent (NOT Skill, NOT Plan)
Parameters:
- subagent_type: "general-implementation-agent"
- prompt: [Include task_context, delegation_context, plan_path, metadata_file_path,
AND the format specification from Stage 4b as shown below]
- description: "Execute implementation for task {N}"
Format Injection: Include the format specification from Stage 4b in the prompt as a clearly-delimited section:
<artifact-format-specification>
## CRITICAL: Summary Format Requirements
You MUST follow this format specification exactly when writing the implementation summary.
Non-compliance will be caught by postflight validation.
{format_content from Stage 4b}
</artifact-format-specification>
Place this section AFTER the delegation context JSON and BEFORE any other instructions.
Memory Context Injection: If memory_context from Stage 4a is non-empty, include it in the prompt as a separate block:
{memory_context from Stage 4a -- already wrapped in <memory-context> tags}
Place the memory context block AFTER the format specification and BEFORE the task-specific instructions. Do NOT inject an empty <memory-context> block when no memories were retrieved.
Literature Briefing Injection: If lit_context from Stage 4a is non-empty, include it in the prompt as a separate block:
{lit_context from Stage 4a -- already wrapped in <literature-briefing> tags}
Place the literature briefing block AFTER the memory context block (if any) and BEFORE the task-specific instructions. Do NOT inject an empty <literature-briefing> block when no literature briefing was generated.
DO NOT use Skill(general-implementation-agent) - this will FAIL.
The subagent will:
- Load implementation context files
- Parse plan and find resume point
- Execute phases sequentially
- Create/modify files as needed
- Create implementation summary
- Write metadata to
specs/{NNN}_{SLUG}/.return-meta.json
- Return a brief text summary (NOT JSON)
Stage 5a: Validate Subagent Return Format
If the subagent's text return parses as valid JSON, log a warning (v1 pattern instead of v2 file-based pattern). Non-blocking -- continue to read metadata file regardless.
Stage 5b: 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 status value "implemented" and the appropriate artifact information.
If you DID use the Agent tool (Stage 5), skip this stage -- the subagent already wrote the metadata.
Stage 5c: Continuation Loop Init
Initialize continuation tracking before entering the postflight loop:
continuation_count=0
max_continuations=3
task_dir="specs/${padded_num}_${project_name}"
cat > "${task_dir}/.continuation-loop-guard" << EOF
{
"session_id": "${session_id}",
"continuation_count": 0,
"max_continuations": 3,
"created": "$(date -u +%Y-%m-%dT%H:%M:%SZ)"
}
EOF
Note: The loop guard ensures that even if the skill is interrupted between iterations, the next invocation can read the count and enforce the limit.
Postflight (ALWAYS EXECUTE)
The following stages MUST execute after work is complete, whether the work was done by a
subagent (Stage 5) or inline (Stage 5b). Do NOT skip these stages for any reason.
Continuation Loop
The postflight stages below run inside a loop. Each iteration processes the return from one
subagent execution. If the subagent returns partial with a handoff_path, a successor
subagent is spawned and the loop continues (up to max_continuations).
while true; do
Stage 6: Parse Subagent Return (Read Metadata File)
Read the metadata file:
metadata_file="specs/${padded_num}_${project_name}/.return-meta.json"
if [ -f "$metadata_file" ] && jq empty "$metadata_file" 2>/dev/null; then
status=$(jq -r '.status' "$metadata_file")
artifact_path=$(jq -r '.artifacts[0].path // ""' "$metadata_file")
artifact_type=$(jq -r '.artifacts[0].type // ""' "$metadata_file")
artifact_summary=$(jq -r '.artifacts[0].summary // ""' "$metadata_file")
phases_completed=$(jq -r '.metadata.phases_completed // 0' "$metadata_file")
phases_total=$(jq -r '.metadata.phases_total // 0' "$metadata_file")
completion_summary=$(jq -r '.completion_data.completion_summary // ""' "$metadata_file")
roadmap_items=$(jq -c '.completion_data.roadmap_items // []' "$metadata_file")
memory_candidates=$(jq -c '.memory_candidates // []' "$metadata_file")
handoff_path=$(jq -r '.partial_progress.handoff_path // ""' "$metadata_file")
else
echo "Error: Invalid or missing metadata file"
status="failed"
fi
Stage 6a: Validate Artifact Content
If subagent status indicates success ("implemented" or "partial") and artifact_path is non-empty, validate the summary artifact against format requirements. This is non-blocking -- warnings are logged but do not prevent postflight from completing.
if [ "$status" = "implemented" ] || [ "$status" = "partial" ]; then
if [ -n "$artifact_path" ] && [ -f "$artifact_path" ]; then
echo "Validating summary artifact..."
if ! bash .claude/scripts/validate-artifact.sh "$artifact_path" summary --fix; then
echo "WARNING: Summary artifact has format issues (non-blocking). Review output above."
fi
fi
fi
Note: The --fix flag attempts auto-repair of missing metadata fields. Validation failures are logged but do not block status update or git commit.
Stage 6b: Commit Phase Progress (Inside Loop)
After each subagent completes (whether implemented, partial, or failed), commit the work:
git add -A
git commit -m "task ${task_number} phase ${phases_completed}: implementation progress
Session: ${session_id}
" || echo "Note: Nothing to commit or commit failed (non-blocking)"
This ensures each subagent's progress is checkpointed in git before proceeding.
Stage 7: Update Task Status (Postflight)
If status is "implemented":
Step 1: Run the centralized status update script to update state.json (status -> "completed", timestamps), TODO.md ([IMPLEMENTING] -> [COMPLETED] in task entry + Task Order), and plan file (status -> [COMPLETED]):
bash .claude/scripts/update-task-status.sh postflight "$task_number" implement "$session_id"
Step 2: Add completion_summary to state.json (implementer-specific, not covered by centralized script):
if [ -n "$completion_summary" ]; then
jq --arg summary "$completion_summary" \
'(.active_projects[] | select(.project_number == '$task_number')).completion_summary = $summary' \
specs/state.json > specs/tmp/state.json && mv specs/tmp/state.json specs/state.json
fi
Step 3: Add roadmap_items for non-meta tasks (implementer-specific):
if [ "$task_type" != "meta" ] && [ "$roadmap_items" != "[]" ] && [ -n "$roadmap_items" ]; then
jq --argjson items "$roadmap_items" \
'(.active_projects[] | select(.project_number == '$task_number')).roadmap_items = $items' \
specs/state.json > specs/tmp/state.json && mv specs/tmp/state.json specs/state.json
fi
Step 4: Propagate memory candidates (if any) with append semantics:
if [ "$memory_candidates" != "[]" ] && [ -n "$memory_candidates" ]; then
jq --argjson new_candidates "$memory_candidates" \
'(.active_projects[] | select(.project_number == '$task_number')).memory_candidates =
((.active_projects[] | select(.project_number == '$task_number')).memory_candidates // []) + $new_candidates' \
specs/state.json > specs/tmp/state.json && mv specs/tmp/state.json specs/state.json
fi
Note: Uses // [] fallback and + append so research candidates (from skill-researcher) and implementation candidates coexist on the same task entry.
Break loop — proceed to Stage 8 (Link Artifacts).
If status is "partial":
Keep status as "implementing" but update resume point. This path remains inline because the centralized update-task-status.sh maps postflight:implement to "completed" only -- it has no "partial" mapping.
jq --arg ts "$(date -u +%Y-%m-%dT%H:%M:%SZ)" \
--argjson phase "$phases_completed" \
'(.active_projects[] | select(.project_number == '$task_number')) |= . + {
last_updated: $ts,
resume_phase: ($phase + 1)
}' specs/state.json > specs/tmp/state.json && mv specs/tmp/state.json specs/state.json
TODO.md stays as [IMPLEMENTING].
Update plan file (if exists): Update the Status field to [PARTIAL]:
.claude/scripts/update-plan-status.sh "$task_number" "$project_name" "PARTIAL"
Continuation decision:
if [ -n "$handoff_path" ] && [ -f "$handoff_path" ] && [ "$continuation_count" -lt "$max_continuations" ]; then
continuation_count=$((continuation_count + 1))
jq --argjson count "$continuation_count" \
--arg ts "$(date -u +%Y-%m-%dT%H:%M:%SZ)" \
'.continuation_count = $count | .last_updated = $ts' \
"${task_dir}/.continuation-loop-guard" > "${task_dir}/.continuation-loop-guard.tmp" \
&& mv "${task_dir}/.continuation-loop-guard.tmp" "${task_dir}/.continuation-loop-guard"
echo "Spawning successor subagent (continuation $continuation_count/$max_continuations)"
echo "Handoff: $handoff_path"
continue
else
if [ -z "$handoff_path" ]; then
echo "Partial return with no handoff_path. User must re-run /implement to resume."
else
echo "Max continuations ($max_continuations) reached. Returning partial."
fi
break
fi
If no handoff_path: Break loop, report partial (user must resume).
If continuation_count >= max_continuations: Break loop, report partial (max reached).
If status is "failed":
Keep status as "implementing" for retry. Do not update plan file (leave as [IMPLEMENTING] for retry).
Break loop — proceed to Stage 8.
done # End Continuation Loop
Stage 8: Link Artifacts
Add artifact to state.json with summary.
IMPORTANT: Use two-step jq pattern to avoid Issue #1132 escaping bug. See jq-escaping-workarounds.md.
if [ -n "$artifact_path" ]; then
jq '(.active_projects[] | select(.project_number == '$task_number')).artifacts =
[(.active_projects[] | select(.project_number == '$task_number')).artifacts // [] | .[] | select(.type == "summary" | not)]' \
specs/state.json > specs/tmp/state.json && mv specs/tmp/state.json specs/state.json
jq --arg path "$artifact_path" \
--arg type "$artifact_type" \
--arg summary "$artifact_summary" \
'(.active_projects[] | select(.project_number == '$task_number')).artifacts += [{"path": $path, "type": $type, "summary": $summary}]' \
specs/state.json > specs/tmp/state.json && mv specs/tmp/state.json specs/state.json
fi
Update TODO.md (if implemented): Regenerate from state.json (state.json artifact update was done in the previous step):
bash .claude/scripts/generate-todo.sh || echo "WARNING: generate-todo.sh failed (non-fatal)" >&2
If the script exits non-zero, log a warning but continue (regeneration errors are non-blocking).
Stage 8a: Lifecycle TTS Notification
Fire TTS and WezTerm tab coloring after artifact linking is complete:
lifecycle_script=".claude/scripts/lifecycle-notify.sh"
if [ -f "$lifecycle_script" ]; then
bash "$lifecycle_script" "$STATE_STATUS" &
fi
Non-blocking: called in background after artifacts are linked. Speaks "Tab N STATUS"
(e.g., "Tab 3 completed") to announce the lifecycle transition.
Stage 9: Git Commit
Commit changes with session ID:
git add -A
git commit -m "task ${task_number}: complete implementation
Session: ${session_id}
Stage 10: Cleanup
Cleanup runs after the continuation loop exits. The .postflight-pending marker persists across loop iterations to ensure the SubagentStop hook fires correctly.
Remove marker, metadata, and loop-guard files:
rm -f "specs/${padded_num}_${project_name}/.postflight-pending"
rm -f "specs/${padded_num}_${project_name}/.postflight-loop-guard"
rm -f "specs/${padded_num}_${project_name}/.continuation-loop-guard"
rm -f "specs/${padded_num}_${project_name}/.return-meta.json"
Stage 11: Return Brief Summary
Return a brief text summary (NOT JSON). Example:
Implementation completed for task {N}:
- All {phases_total} phases executed successfully
- Key changes: {summary of changes}
- Created summary at specs/{NNN}_{SLUG}/summaries/MM_{short-slug}-summary.md
- Status updated to [COMPLETED]
- Changes committed
Error Handling
See rules/error-handling.md for general patterns. Skill-specific behaviors:
- Input validation errors: Return immediately with error message
- Metadata file missing: Keep status as "implementing", do not cleanup marker, report to user
- Git commit failure: Non-blocking (log and continue)
- Subagent timeout: Return partial status, keep "implementing" for resume
Pre-Delegation Boundary
Before spawning the implementation sub-agent, this skill MUST NOT:
- Read source files - Source files are read by the sub-agent, not the lead
- Grep or glob the codebase - Codebase exploration is sub-agent work
- Use MCP tools - Domain tools (LSP, build, etc.) are for sub-agent use only
- Analyze source code - Code analysis belongs to the implementation agent
- Run build or test commands - Verification is done by the sub-agent
The pre-delegation phase is LIMITED TO:
- Reading the plan file to locate phases and extract the plan path
- Reading state.json and TODO.md for status updates
- Preparing the delegation context JSON
- Reading the summary format file for injection (Stage 4b)
- Spawning the sub-agent with the Agent tool
MUST NOT (Postflight Boundary)
After the agent returns -- whether with status implemented, partial, or failed -- this skill MUST proceed immediately to Stage 6 (read metadata file). The skill MUST NOT:
- Read source files - Source files were the subagent's responsibility
- Edit source files - All implementation work is done by the subagent
- Run build/test commands - Verification is done by the subagent
- Use MCP tools - Domain tools are for subagent use only
- Grep or glob the codebase - Analysis is subagent work
- Write summary/reports - Artifact creation is done by the subagent
Continuation Policy: If the subagent returned partial status WITH a handoff_path in its metadata, the lead skill MAY spawn a successor subagent to continue the work automatically (see Continuation Loop in Postflight). This is the preferred path for context exhaustion recovery.
If the subagent returned partial status WITHOUT a handoff_path, the lead skill MUST report partial and let the user re-run /implement to resume.
If the subagent returned failed status, the lead skill MUST NOT attempt to continue or "fill in" the subagent's work. Report the failure and let the user investigate.
The postflight phase is LIMITED TO:
- Reading agent metadata file (.return-meta.json)
- Updating state.json via jq
- Updating TODO.md status marker via Edit or script
- Linking artifacts in state.json
- Git commit
- Cleanup of temp/marker files
Reference: @.claude/context/standards/postflight-tool-restrictions.md