benbrastmckie/nvim/skill-books-implementation

Books Implementation Skill

Thin wrapper that delegates books implementation to books-implementation-agent subagent. This skill also serves the books:certify sub-route: no dedicated lifecycle skill exists for it, since books:certify maps to the same base agents as books in the manifest's routing_agents block (the lean4:lake precedent) — a certification-focused implementation task routes here, not to a separate skill.

Trigger Conditions

This skill activates when:

• Task type is "books" (or the books:certify sub-route)
• /implement command targets a books task
• Plan exists and task is ready for implementation

Execution Flow

Stage 1: Input Validation

Validate task_number exists and task type is "books" (or "books:certify").

Stage 2 + Stage 3: Preflight Status Update and Postflight Marker

Source skill-base.sh once, then follow @.claude/context/patterns/skill-preflight-flow.md in full for Stage 2 (preflight status update) and Stage 3 (marker creation):

source .claude/scripts/skill-base.sh
padded_num=$(printf "%03d" "$task_number")
skill_name="skill-books-implementation"
operation="implement"

Stage 4a: Memory Retrieval and Literature Detection

Skip memory retrieval if: clean_flag is true (from --clean).

if [ "$clean_flag" != "true" ]; then
  memory_context=$(bash .claude/scripts/memory-retrieve.sh "$description" "$task_type" "" 2>/dev/null) || memory_context=""
fi

Follow @.claude/context/patterns/lit-stage4a-flow.md in full to resolve --lit and set lit_context, exactly as skill-orchestrate does. This skill supplies the shared block's preconditions: lit_flag, description, orchestrator_mode (default "false" when unset).

Stage 4: Prepare Delegation Context

Include task_context, plan_path, metadata_file_path, and gate_flag (forwarded unchanged from the dispatch context, defaulting to false when absent — the advisory gate tier is opt-in and this skill never decides it). If memory_context and/or lit_context from Stage 4a are non-empty, include them in the prompt (memory context first, then literature briefing). Do NOT inject an empty block for either.

Stage 5: Invoke Subagent

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

Stage 5b: Self-Execution Fallback

Follow @.claude/context/patterns/skill-self-execution-fallback.md in full. This skill's success status value for that block's write obligation is "implemented".

Self-review before writing metadata: if this fallback path authors or modifies any book module, book.toml, or Lean file directly (rather than wholesale re-delegating to another skill/agent), it bypasses books-implementation-agent's own Stage 4C entirely — so before writing .return-meta.json with status: "implemented", re-read every file this inline path touched, by path, against rules/books.md's six non-negotiables. A successful lake build does NOT satisfy this check.

Postflight (ALWAYS EXECUTE)

The following stages MUST execute after work is complete, whether the work was done by a subagent or inline (Stage 5b). Do NOT skip these stages for any reason.

Stage 6: Parse Subagent Return

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

Stage 6d: Advisory Gate Tier Surface (Read from Metadata)

Read the agent-recorded gate block, if any, from metadata and surface it. The gate invocation itself was performed by the agent in its Stage 5 Final Verification — this stage reads that recorded result and MUST NOT re-run it, per @.claude/context/standards/postflight-tool-restrictions.md and this skill's own "MUST NOT (Postflight Boundary)" section below. This stage does not invoke books-gate.sh, does not run a build, and does not grep source.

gate_ran=$(jq -r '.gate.ran // false' "$metadata_file" 2>/dev/null)
gate_lint_status=$(jq -r '.gate.layer_lint.status // ""' "$metadata_file" 2>/dev/null)
gate_rules_matched=$(jq -r '.gate.layer_lint.rules_matched // 0' "$metadata_file" 2>/dev/null)
gate_rules_total=$(jq -r '.gate.layer_lint.rules_total // 0' "$metadata_file" 2>/dev/null)
gate_violation_count=$(jq -r '.gate.layer_lint.violation_count // 0' "$metadata_file" 2>/dev/null)
gate_closure_status=$(jq -r '.gate.books_meta_closure.status // ""' "$metadata_file" 2>/dev/null)
 
if [ "$gate_ran" = "false" ] && [ -z "$gate_lint_status" ]; then
    echo "Stage 6d: INFO — no gate block recorded (--gate not requested, or the agent stopped before invocation); proceeding"
elif [ "$gate_lint_status" = "pass" ] && [ "$gate_closure_status" = "pass" ]; then
    echo "Stage 6d: Advisory gate tier PASS — layer_lint=pass (${gate_rules_matched}/${gate_rules_total} rules matched), books_meta_closure=pass"
else
    echo "Stage 6d: *** ADVISORY GATE FINDING ***"
    echo "  layer_lint.status: ${gate_lint_status} (rules matched: ${gate_rules_matched}/${gate_rules_total}, violations: ${gate_violation_count})"
    echo "  books_meta_closure.status: ${gate_closure_status}"
    if [ "$gate_lint_status" = "pass_vacuous" ]; then
        echo "  NOTE: pass_vacuous is NOT a pass — the lint reported no violations while matching 0 rules, so nothing was actually checked."
    fi
    echo "  This is ADVISORY ONLY — completion is proceeding regardless. See the implementation"
    echo "  summary's gate section for full detail."
fi

Asymmetry note (deliberate, not an omission): unlike a compliance_check == "failed" branch, which sets status="partial", this stage MUST NOT assign status on any gate status, however severe. The tier is advisory-only by binding design decision — see ### gate (optional) in @.claude/context/formats/return-metadata-file.md. It ADDS a cheap intermediate tier below the existing fail-closed one; it relaxes nothing.

Gate-tier background — plain pointers, read on demand, never eager imports: context/project/books/domain/gate-tiers.md and context/project/books/tools/certify-guide.md.

Stage 7, 7a, 8, 8a, 9: Postflight Status, Memory Candidates, Artifact Linking, Notify, Cleanup

Follow @.claude/context/patterns/skill-postflight-flow.md in full: field_name=**Summary**, next_field=**Description**.

Error Handling

Input Validation Errors

Return immediately if task not found or wrong task type.

Metadata File Missing

Keep status as "implementing", report error.

Git Commit Failure

Non-blocking: Log failure but continue.

MUST NOT (Postflight Boundary)

After the agent returns, this skill MUST NOT:

1. Edit book/Lean/TOML files - All books work is done by agent
2. Run `lake build` or `books-tool` - 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).