List all available thinking chains: built-ins (master router, default freeform sequential thinking) plus file-defined chains from the global (~/.claude/kata), pack (/packs/, declared in /.claude/kata.json) and project (/.claude/kata) layers. Shadowing: project > pack > global. Also reports invalid chain files (with reasons), missing packs, pack conflicts and shadowing.

Start a thinking chain by name. When the task shape clearly matches a chain, call that chain directly; when nothing matches or the task needs multi-step reasoning, call run_chain("master") to route between PASS (no chains), "default" (freeform step-by-step thinking) and custom chains. Checklist chains return one complete checklist (single-shot). Staged/freeform chains open a session; continue with advance_chain.

Submit the current stage's result and receive the next stage. Staged chains: pass exactly one of stage_output (work done for this stage) or skip_reason (why the stage was skipped). Freeform default chain: pass each thought as stage_output; set done: true with your final verified thought. expected_stage_index guards against retries: re-sending the previous index returns the same response idempotently.

Create or update a custom thinking chain as a Markdown file with YAML frontmatter (fields: name, description, mode: checklist|staged, optional domain/language/schema_version). The content is fully validated before writing; nothing is written on validation failure. name must equal the frontmatter name. Existing chains are only replaced when overwrite: true.

Export a chain's raw Markdown source for sharing (returns content, sha256, suggested filename). To import a shared chain, read its file and call save_chain with the content. If the name exists in both global and project scope, pass scope to disambiguate.