Rebuild the vocabulary step on embeddings and drop the screen track

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -6,27 +6,35 @@
   Messages API: model `claude-sonnet-4-6`, `temperature=0`,
   thinking disabled, Batch API where possible.
 - Prompt definition files live in
-  `prompts/<track>-<step>-<task>.md` (e.g. 01-01-tag.md; no
+  `prompts/<step>-<substep>-<task>.md` (e.g. 01-tag.md; no
   version suffix -- versions live in git history) and are
-  passed verbatim as the system prompt.
-- Per-song LLM judgments (coding, screening) run the same
-  definition file twice, then a separate arbitration step
-  settles only the script-computed disagreements
+  passed verbatim as the system prompt.  The number names a
+  step of the research procedure, not the file: the
+  deterministic vocabulary step (step 2) has no definition
+  file yet holds its own number.  Zero padding is for
+  sorting only -- prose says "step 1", "step 3-2".
+- Per-song LLM judgments (coding) run the same definition
+  file twice, then a separate arbitration step settles only
+  the script-computed disagreements
   ("2 runs + 1 arbitration").  Free-generation steps run
-  twice and both outputs are pooled, unarbitrated.
-  Vocabulary-building steps (convergence) run once as a
-  recorded pass.  If an arbitration or validation outcome is
-  unexpected, revise the definition file and repeat that
-  cycle; never patch results by hand.
+  twice and both outputs are pooled, unarbitrated.  The
+  vocabulary is built by a deterministic subcommand
+  (embedding + clustering), not by an LLM.  If an arbitration
+  or validation outcome is unexpected, revise the definition
+  file and repeat that cycle; never patch results by hand.
 - Each run of a step is archived self-contained under the
   destination directory given explicitly on the `run-llm`
-  command line (by convention `runs/<definition-file>/run<N>/`):
+  command line (by convention `runs/<step>/run<N>/`):
   prompt snapshot, raw output, and `meta.json` (model ID,
   parameters, timestamps, batch ID).  The two runs of a step
   are two separate invocations of `run-llm`.  An arbitration
   pass is a step of its own with its own archive.  Replacing
   an existing run archive requires an explicit flag;
-  superseded runs live in git history.
+  superseded runs live in git history.  Deterministic steps
+  archive under `runs/<step>/` with no `run<N>` level.
+- Token usage and cost of every `run-llm` execution are
+  recorded in `docs/run-costs.md` in the same commit as the
+  run archive.
 - Scripts read the API key from the `ANTHROPIC_API_KEY`
   environment variable (`.env`, gitignored).