docs(adr): Add ADR-009 slash command file organization

Documents the finding that:
- Claude Code follows symlinks during command discovery
- Non-command files must be moved outside commands/ to hide from picker
- Schema specs go in docs/src/context/
- Test/example files go in tests/

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

Author: aRustyDev

docs/src/adr/009-slash-command-file-organization.md

@@ -0,0 +1,81 @@
+# ADR-009: Slash Command File Organization
+
+## Status
+
+Accepted
+
+## Context
+
+Claude Code discovers slash commands by scanning `.claude/commands/` for markdown files. This project symlinks `.claude/commands/` to `context/commands/` to organize commands alongside other context components (agents, rules, skills).
+
+We encountered an issue where non-command files (schema specifications, example plans) were appearing in the slash command autocomplete menu. These files:
+
+- `context/commands/context/plan/SCHEMA.md` - Schema specification document
+- `context/commands/context/plan/examples/*.md` - Example/test plan files
+
+We needed to hide these from the command picker while keeping them accessible for reference.
+
+## Decision
+
+**Move non-command markdown files outside the commands directory.**
+
+### File Organization
+
+| Content Type | Location | Appears in `/` menu |
+|--------------|----------|---------------------|
+| Slash commands | `context/commands/**/*.md` | Yes |
+| Schema specifications | `docs/src/context/*/schema.md` | No |
+| Test/example files | `tests/**/*.md` | No |
+
+### Tested Approaches
+
+| Approach | Result |
+|----------|--------|
+| Symlinks pointing outside commands/ | **Failed** - symlinks ARE followed |
+| Files without YAML frontmatter | **Failed** - still discovered |
+| `user-invocable: false` frontmatter | Not tested - would require adding frontmatter to non-commands |
+| Move files out of commands/ | **Works** - files not discovered |
+
+### Key Finding
+
+Claude Code follows symlinks during command discovery. A symlink at `context/commands/foo/bar.md` pointing to `../../docs/bar.md` will still include `bar.md` in the command picker.
+
+## Consequences
+
+### Positive
+
+- Clean separation between commands and reference documentation
+- Slash command autocomplete only shows actual commands
+- Test files live in `tests/` following standard conventions
+- Documentation lives in `docs/` for mdbook integration
+
+### Negative
+
+- Commands must use longer paths to reference schema/examples
+- Moving files requires updating cross-references
+
+### Implementation
+
+```bash
+# Schema specifications
+docs/src/context/
+└── plan/
+    └── schema.md
+
+# Test/example files
+tests/
+└── plans/
+    ├── valid-plan.md
+    ├── invalid-missing-objectives.md
+    ├── invalid-missing-phases.md
+    └── invalid-phase-missing-files.md
+
+# Commands reference these locations
+context/commands/context/plan/create.md → refs docs/src/context/plan/schema.md
+context/commands/context/plan/review.md → refs docs/src/context/plan/schema.md
+```
+
+## Related
+
+- ADR-001: Primary Data Store (project organization context)
+- `.claude/commands/` symlink to `context/commands/`