docs(05-03): complete gsd-indexer plan

Tasks completed: 1/1
- Create gsd-indexer agent definition

SUMMARY: .planning/phases/05-subagent-codebase-analysis/05-03-SUMMARY.md

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.planning/phases/05-subagent-codebase-analysis/05-03-SUMMARY.md

@@ -0,0 +1,135 @@
+---
+phase: 05-subagent-codebase-analysis
+plan: 03
+title: gsd-indexer Agent Definition
+subsystem: agents
+tags: [subagent, indexing, file-analysis, context-preservation]
+
+dependency-graph:
+  requires:
+    - 05-01 (gsd-entity-generator pattern reference)
+    - gsd-codebase-mapper.md (agent structure pattern)
+    - analyze-codebase.md Step 3 (regex patterns)
+  provides:
+    - gsd-indexer subagent definition
+    - File indexing via subagent delegation
+    - Context-preserving index generation
+  affects:
+    - 05-04 (analyze-codebase integration)
+    - Steps 2-3 context exhaustion fix
+
+tech-stack:
+  added: []
+  patterns:
+    - Subagent direct-write pattern
+    - Statistics-only return pattern
+    - Regex-based export/import extraction
+
+key-files:
+  created:
+    - agents/gsd-indexer.md
+  modified: []
+
+decisions:
+  - id: absolute-path-keys
+    choice: Use absolute paths as index keys
+    rationale: O(1) lookup, matches existing index.json schema
+
+metrics:
+  duration: 1 min 23 sec
+  completed: 2026-01-21
+---
+
+# Phase 05 Plan 03: gsd-indexer Agent Definition Summary
+
+**One-liner:** Subagent definition for file indexing that extracts exports/imports using validated regex patterns and writes index.json directly to disk.
+
+## What Was Built
+
+Created `agents/gsd-indexer.md` following the `gsd-entity-generator.md` pattern:
+
+**Agent structure:**
+- Frontmatter with name, description, tools (Read, Write, Bash), color
+- Role section explaining spawn context from `/gsd:analyze-codebase`
+- `<why_this_matters>` section explaining index consumers (convention detection, entity generation, PostToolUse hook)
+- 4-step process: parse_input, process_each_file, write_index, return_statistics
+
+**Regex patterns (exact match with analyze-codebase Step 3):**
+
+Export patterns:
+| Pattern | Regex | Purpose |
+|---------|-------|---------|
+| Named exports | `export\s*\{([^}]+)\}` | `export { a, b }` |
+| Declaration | `export\s+(?:const\|let\|var\|function\*?\|async\s+function\|class)\s+(\w+)` | `export const foo` |
+| Default | `export\s+default\s+(?:function\s*\*?\s*\|class\s+)?(\w+)?` | `export default` |
+| CommonJS object | `module\.exports\s*=\s*\{([^}]+)\}` | `module.exports = { }` |
+| CommonJS single | `module\.exports\s*=\s*(\w+)\s*[;\n]` | `module.exports = X` |
+| TypeScript | `export\s+(?:type\|interface)\s+(\w+)` | `export type/interface` |
+
+Import patterns:
+| Pattern | Regex | Purpose |
+|---------|-------|---------|
+| ES6 | `import\s+(?:\{[^}]*\}\|\*\s+as\s+\w+\|\w+)\s+from\s+['"]([^'"]+)['"]` | `import X from 'y'` |
+| Side-effect | `import\s+['"]([^'"]+)['"]` | `import 'styles.css'` |
+| CommonJS | `require\s*\(\s*['"]([^'"]+)['"]\s*\)` | `require('x')` |
+
+**Index schema (matches Step 5):**
+```javascript
+{
+  version: 1,
+  updated: Date.now(),
+  files: {
+    "/absolute/path": {
+      exports: [],
+      imports: [],
+      indexed: Date.now()
+    }
+  }
+}
+```
+
+**Critical rules:**
+- Write index.json directly (never return contents)
+- Use exact regex patterns from Step 3
+- Absolute paths as keys for O(1) lookup
+- Handle read errors gracefully (log, continue)
+- Return statistics only (~10 lines)
+
+## Tasks Completed
+
+| Task | Name | Commit | Key Files |
+|------|------|--------|-----------|
+| 1 | Create gsd-indexer agent definition | 5d03e14 | agents/gsd-indexer.md |
+
+## Deviations from Plan
+
+None - plan executed exactly as written.
+
+## Decisions Made
+
+1. **Absolute path keys**
+   - Continues existing index.json schema decision from 01-01
+   - Enables O(1) lookup for any file path
+   - Consistent with PostToolUse hook expectations
+
+## Verification Results
+
+- [x] File exists at `agents/gsd-indexer.md`
+- [x] Frontmatter valid YAML (name, description, tools, color)
+- [x] Role section explains subagent purpose (spawned by analyze-codebase)
+- [x] Process has 4 steps: parse, process, write, return
+- [x] Export regex patterns match Step 3 exactly (6 patterns)
+- [x] Import regex patterns match Step 3 exactly (3 patterns)
+- [x] Index schema matches Step 5 format (version, updated, files)
+- [x] Critical rules section matches gsd-entity-generator style
+- [x] Returns statistics only (not index contents)
+
+## Next Phase Readiness
+
+**Prerequisites for 05-04:**
+- [x] gsd-indexer.md exists
+- [x] Agent follows expected patterns (direct write, stats return)
+- [x] Regex patterns validated against analyze-codebase Step 3
+- [x] Index schema matches existing expectations
+
+**Ready for:** Integration into `/gsd:analyze-codebase` command Steps 2-3 (Plan 05-04)