feat: add test-first validation gate in Do phase

skills/do-phase/SKILL.md

@@ -165,3 +165,29 @@ Before your final commit, verify:
 - [ ] Every logical step has its own commit
 - [ ] Output summary is complete and accurate
 - [ ] Branch name follows convention
+
+## Test-First Gate
+
+Before the Maker's output is accepted, the orchestrator validates that tests were included.
+
+### Validation Logic
+
+Read `do-maker-files.txt`. Check if any file path matches common test patterns:
+- `*test*`, `*spec*`, `*.test.*`, `*.spec.*`, `*_test.*`, `*_spec.*`
+- Files in directories named `test/`, `tests/`, `__tests__/`, `spec/`
+
+For writing domain projects, this gate is skipped.
+
+### Outcomes
+
+| Result | Action |
+|--------|--------|
+| Test files found | Pass — proceed to Check phase |
+| No test files, code domain | **Warn** — emit WARNING event, note in do-maker.md |
+| No test files + Creator specified tests | **Block** — re-run Maker with test instruction (1 retry) |
+| Writing domain | Skip gate entirely |
+
+The block case triggers a targeted re-run with prompt:
+"The proposal specified these test cases: <test strategy section>. No test files
+were found in your changes. Add the specified tests before finishing."
+This is one retry within the Do phase, not a full PDCA cycle.