diff --git a/conductor/tracks/twitter_threads_extraction_20260705/plan.md b/conductor/tracks/twitter_threads_extraction_20260705/plan.md
index 1d0407c9..7f5312c1 100644
--- a/conductor/tracks/twitter_threads_extraction_20260705/plan.md
+++ b/conductor/tracks/twitter_threads_extraction_20260705/plan.md
@@ -87,11 +87,11 @@ git commit -m "feat(twitter_threads): scaffold package + error types + typed dat
 
 ---
 
-## Phase 2: `render_markdown.py` (the pure-function module; TDD-first)
+## Phase 2: `render_markdown.py` (the pure-function module; TDD-first) [checkpoint: ef98f6d1]
 
 Focus: the Markdown emission module. This is pure (no network, no subprocess), so it's the easiest to TDD and the highest-confidence module.
 
-- [ ] **Task 2.1: Write failing tests for `render_markdown.py`**
+- [x] **Task 2.1: Write failing tests for `render_markdown.py`**
 
 WHERE: `tests/test_twitter_threads_render.py`
 WHAT: 5+ tests:
@@ -104,7 +104,7 @@ WHAT: 5+ tests:
 HOW: Construct `ThreadData` fixtures inline (no network). Assert on the returned Markdown string.
 VERIFY: `uv run pytest tests/test_twitter_threads_render.py` FAILS (module doesn't exist yet).
 
-- [ ] **Task 2.2: Implement `render_markdown.py`**
+- [x] **Task 2.2: Implement `render_markdown.py`**
 
 WHERE: `scripts/twitter_threads/render_markdown.py`
 WHAT: The `render_markdown(thread: ThreadData, media_paths: dict[str, list[Path]], output: Path) -> Result[Path, ErrorInfo]` function.
@@ -117,7 +117,7 @@ HOW:
 - Return `Result.ok(output)` on success; `Result.err(...)` on file-write failure.
 VERIFY: `uv run pytest tests/test_twitter_threads_render.py` PASSES.
 
-- [ ] **Task 2.3: Commit Phase 2**
+- [x] **Task 2.3: Commit Phase 2**
 
 ```bash
 git add scripts/twitter_threads/render_markdown.py tests/test_twitter_threads_render.py