stata-code

stata-code Skill

stata-code is an agent-native Stata bridge. This skill briefs Claude on how to drive Stata efficiently through it. Do not regress to log-grepping; the schema is the contract.

1. When this skill applies

Activate this skill whenever the user mentions Stata in a way that implies execution, inspection, or repair, e.g.:

• "Run this regression in Stata."
• "Why does summarize mpgg fail?"
• "Fix this do-file and rerun it until it passes."
• "Open analysis.ipynb cell 3 and replace it with a robust SE specification."
• "Pull e(b) and the residual variance after my last regress."
• "What does r2_a look like across these three specifications?"

Confirm the MCP server is wired up with stata_info() once per session. If it returns available: false, surface the install hint (pip install "stata-code[mcp]") and stop — do not try to shell out to Stata directly.

2. The 15 MCP tools (cheat sheet)

Tool	Use it when…
stata_run(code, session_id?, …)	The user wants Stata code executed. Default to session_id="main".
stata_info()	At session start, or when capabilities / Stata edition matter.
get_log(ref)	A prior stata_run returned log.truncated: true and you need the full log.
get_graph(ref, format?)	The user wants graph bytes (export, display, embed).
get_matrix(ref)	A matrix in results.r.matrices or results.e.matrices came back with values: null (over 10k cells).
list_sessions()	The user mentions multiple parallel Stata "tabs" or you need to find a session by id.
cancel_session(session_id)	A run is hung or the user said "stop". Subprocess workers terminate; in-flight code is killed.
reset_session(session_id?)	The user wants clear all-style fresh state for a session.
notebook_outline(path)	The user references a .ipynb and you need to know which cells exist.
notebook_get_cell(path, cell_id)	Read one cell's source plus a compact outputs summary.
notebook_locate(path, snippet/regex/error_text)	Find which cell contains a given snippet or the cell that produced an error message.
notebook_edit_cell(path, cell_id, source, expected_source?)	Atomic cell replace. Pass expected_source for optimistic concurrency.
notebook_insert_cell(path, after_cell_id, source, cell_type?)	Insert a new cell with a fresh nbformat 4.5 uuid.
notebook_delete_cell(path, cell_id)	Remove a cell.
list_runs(log_dir or origin_path, cell_id?, session_id?, ok?, since?, limit?, offset?)	Search the on-disk run-bundle index — "show me my last failed run on this file". Use offset to page through long histories.

There are also MCP resources (stata://schema/run-result, log://..., graph://..., matrix://...) and prompts (run_do_file_and_report, debug_stata_error, fix_and_rerun_until_passes, replication_audit, summarize_estimation_results).

3. The v1.0 RunResult schema (read this once)

Every stata_run reply has this shape (full spec: stata://schema/run-result or SCHEMA.md in the repo):

{
  "ok": true,                      // ← branch on this first
  "rc": 0,                         // Stata _rc; -1 adapter crash, -2 timeout, -3 cancelled
  "session_id": "main",
  "request_id": "01HX…",
  "started_at": "2026-…Z",
  "elapsed_ms": 234,
  "stata_elapsed_ms": 198,
  "stata": {"version": "18.0", "edition": "MP", "backend": "pystata"},

  "log": {
    "head": "...",                 // first 20 lines by default
    "tail": "...",                 // last 20 lines (empty when not truncated)
    "lines_total": 42,
    "bytes_total": 2380,
    "truncated": true,
    "error_window": null,          // ~10 lines around the failure on errors
    "ref": "log://run-7f3a9b"      // fetch full via get_log(ref)
  },

  "results": {
    "r": {"scalars": {…}, "macros": {…}, "matrices": {…}},
    "e": {"scalars": {…}, "macros": {…}, "matrices": {"b": {rows, cols, values, ref}, …}},
    "last_estimation_cmd": "regress"
  },

  "dataset": {"frame": "default", "n_obs": 74, "n_vars": 12, "changed": false, …},
  "graphs":   [{"ref": "graph://…", "format": "png", "source_command": "scatter …", "source_line": 5}],
  "warnings": [{"kind": "convergence", "message": "…"}],

  "error": null,                   // populated iff ok=false; see §5
  "origin": null,                  // echoes origin_* request fields
  "schema_version": "1.0",
  "capabilities": ["log_truncation", "graph_ref", "matrix_ref", "multi_session", …]
}

Key invariants:

• Branch on ok first; never grep log.head to decide success.
• Scalars are native numbers. Missing is JSON null, not ".".
• Matrices over ~10k cells arrive with values: null + a matrix:// ref — call get_matrix lazily.
• Graphs default to refs, not base64 bytes. Only ask for include_graphs: "inline" if you genuinely need the bytes.

4. Token-economy defaults — keep responses small

stata-code is already aggressive about this; do not undo its work:

• Do not pass include_full_log: true unless the user asked for the full log or the head/tail clearly miss the relevant content.
• Do not pass include_graphs: "inline" unless the agent needs the bytes (rare; usually you want to surface the ref so the editor / user can fetch it).
• Do not read get_log(ref) proactively; only when you actually need lines beyond head + tail + error_window.
• Do quote specific numbers from results.e.scalars / results.r.scalars rather than dumping JSON.

5. The typed-error taxonomy (32 kinds)

On failure, the error block looks like:

{
  "kind": "varname_not_found",      // ← branch on this, not on rc or message
  "rc": 111,
  "rc_label": "variable not found",
  "message": "variable mpgg not found",
  "command": "summarize mpgg",
  "line": 3,
  "context": {"before": ["use auto"], "failing": "summarize mpgg", "after": []},
  "commands_executed": 1,
  "varname": "mpgg",               // populated for varname_* / file_* / name_* kinds
  "suggestions": [{"action": "Did you mean `mpg`?", "command": "describe"}]
}

Kinds you will see most often:

• varname_not_found (rc 111) — varname is filled; check dataset.variables for the right name.
• syntax (rc 9/100/198) — usually a typo; inspect context.failing.
• command_not_found (rc 199) — often needs ssc install <pkg> or net install.
• file_not_found / file_exists / file_corrupt (rc 322/601/602/604) — path is filled.
• not_sorted (rc 119) — append sort <var> before the failing command.
• name_conflict (rc 110) — use replace or pick a fresh name.
• convergence / infeasible (rc 430/491) — model issue, not code typo.
• no_estimation_results (rc 301) — likely predict/margins before any regress.
• timeout (synthetic rc -2) / cancelled (-3) / adapter_crash (-1) — system-level; do not retry blindly.

Use error.suggestions as hints, not directives. Apply a fix automatically only if the user explicitly asked you to repair and rerun.

6. The two big workflows

6.1 Diagnose-only (default)

1. stata_run(code)
2. If ok: report scalars/warnings. Done.
3. If not ok:
   - State error.kind, error.line, error.context.failing.
   - List error.suggestions verbatim.
   - Ask the user how to proceed (do not edit source files).

6.2 Fix-and-rerun-until-passes (only when the user said so)

loop:
  result = stata_run(current_code)
  if result.ok: break
  apply minimal fix derived from result.error (kind + varname/path/context):
    - varname_not_found → use error.varname / dataset.variables to suggest the closest match
    - file_not_found    → fix the path or generate the missing file
    - syntax            → fix the line in result.error.line
    - not_sorted        → prepend `sort <var>`
    - name_conflict     → add `replace` or drop the conflicting object first
  rewrite the .do file or notebook cell
  guard against infinite loops (cap at ~5 iterations; bail with a summary if stuck)

For notebook repair, use notebook_edit_cell(path, cell_id, source, expected_source=<old>) with optimistic-concurrency so a user-side edit aborts your write rather than silently overwriting it.

7. Multi-session etiquette

• Default session is "main". Long analyses with conflicting state belong in named sessions (session_id="model_a" or "model-a"). Valid ids match [A-Za-z0-9_-]+; the backend maps ids that are not legal Stata frame names to private frames and still echoes the public id.
• The VS Code extension calls sessions "tabs". A new session lazily spawns or maps to a Stata frame; data does not cross.
• After heavy state changes, prefer reset_session(session_id) over rerunning the file with clear all — it is cheaper and clears refs.

8. Origin metadata (helpful for run-bundle audit)

When the user supplies a source file or notebook cell, pass:

• origin_path: absolute path of the .do / .ipynb
• origin_kind: "file", "selection", "line", "cell", "section", "code"
• origin_label: "analysis/main.do:42" or similar
• origin_cell_id: nbformat 4.5 cell uuid when it's a notebook cell

The runner echoes these into result.origin and writes them to the on-disk run-bundle manifest. list_runs then finds prior runs by cell or by file.

9. Things to NOT do

• Do not shell out to stata / do-file editor / pystata directly. Use stata_run.
• Do not parse English from log.head to detect success — use ok / rc / error.kind.
• Do not retry a failing command unchanged. The taxonomy tells you why it failed; act on it or report it.
• Do not assume e() is populated after a non-estimation command. Check results.last_estimation_cmd first.
• Do not rewrite a .do file or .ipynb cell unless the user asked for repair. Diagnostics first.
• Do not paste graph base64 into chat unless the user explicitly asked for bytes; graphs go through get_graph(ref).

10. Reference

• Full schema: SCHEMA.md in the repo or the MCP resource stata://schema/run-result.
• Server capabilities + tool list: MCP resource stata://server/capabilities.
• Examples (DiD, IV, graphs, multi-session, large matrices): examples/ in the repo.
• License: MIT (stata-code itself); Stata is a registered trademark of StataCorp LLC.