diff --git a/skills/do-phase/SKILL.md b/skills/do-phase/SKILL.md
index b4f7470..39d560a 100644
--- a/skills/do-phase/SKILL.md
+++ b/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.
diff --git a/skills/run/SKILL.md b/skills/run/SKILL.md
index 9eb6b2c..daaa244 100644
--- a/skills/run/SKILL.md
+++ b/skills/run/SKILL.md
@@ -245,6 +245,28 @@ After Maker returns:
 
 **Critical:** Verify the Maker committed its changes before proceeding. If uncommitted changes exist, instruct the Maker to commit.
 
+#### 2a-ii. Test-First Validation
+
+After Maker completes, check `do-maker-files.txt` for test files:
+```bash
+TEST_FILES=$(grep -iE '(test|spec)' ".archeflow/artifacts/${RUN_ID}/do-maker-files.txt" || true)
+```
+
+If `TEST_FILES` is empty and domain is not `writing`:
+1. Check if `plan-creator.md` contains a `### Test Strategy` section
+2. If yes: re-run Maker with targeted test instruction (one retry within Do phase)
+3. If no test strategy specified: emit WARNING event and proceed
+
+```bash
+./lib/archeflow-event.sh "$RUN_ID" decision do "" \
+  '{"what":"test_first_gate","chosen":"<pass|warn|retry>","rationale":"<reason>"}' "$SEQ_MAKER_COMPLETE"
+```
+
+The re-run prompt for the retry case:
+> "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. If the retry also produces no tests, emit WARNING and proceed to Check.
+
 #### 2b. Phase Transition: Do to Check
 
 ```bash