feat(cli): add --json to slm runs list

CHANGELOG.md

@@ -8,6 +8,8 @@ interfaces; each entry says what moved. Milestones (M0, M1, …) are described i
 ## [Unreleased]
 
 ### Added
+- `slm runs list --json` prints the runs as a JSON array (run ID plus the fields of `status.json`) for
+  scripts and notebooks. Works with `--project`.
 - Model cards open with Hugging Face Hub metadata (licence, library, task, tags), so an export can be
   uploaded as is. A new optional Project API hook, `model_card_info()`, gives the licence, subject tags
   and data statement; `abc_music` and `shakespeare_char` state theirs (ADR 0010). Export code version 4.

src/slmkit/cli.py

@@ -352,8 +352,11 @@ def _short(n: float) -> str:
 @_friendly_errors
 def runs_list(
     project: str | None = typer.Option(None, "--project", help="Only show runs for this project."),
+    as_json: bool = typer.Option(False, "--json", help="Print the runs as a JSON array."),
 ) -> None:
     """Every run: progress, GPU-hours used and left, best validation loss, last checkpoint."""
+    import json
+
     from slmkit.train.run import list_runs
 
     rows = list_runs()
@@ -364,6 +367,9 @@ def runs_list(
             if isinstance(st.get("experiment"), str)
             and st["experiment"].partition("/")[0] == project
         ]
+    if as_json:
+        typer.echo(json.dumps([{**st, "run_id": path.name} for path, st in rows], indent=2))
+        return
     if not rows:
         message = (
             "no runs yet under $SLM_HOME/runs"

tests/unit/test_runs.py

@@ -43,3 +43,24 @@ def test_runs_list_can_filter_by_project(slm_home: Path) -> None:
     assert filtered.exit_code == 0, filtered.output
     assert "abc run" in all_runs.output and "chess run" in all_runs.output
     assert "abc run" in filtered.output and "chess run" not in filtered.output
+
+
+def test_runs_list_json(slm_home: Path) -> None:
+    _write_status(slm_home, "run-abc123456789", "abc_music/micro_v1", "abc run")
+    _write_status(slm_home, "run-chess123456", "chess/nano", "chess run")
+
+    all_runs = CliRunner().invoke(app, ["runs", "list", "--json"])
+    filtered = CliRunner().invoke(app, ["runs", "list", "--json", "--project", "chess"])
+
+    assert all_runs.exit_code == 0, all_runs.output
+    runs = json.loads(all_runs.output)
+    assert {r["run_id"] for r in runs} == {"run-abc123456789", "run-chess123456"}
+    assert runs[0]["tokens_seen"] == 1000
+    assert [r["name"] for r in json.loads(filtered.output)] == ["chess run"]
+
+
+def test_runs_list_json_empty(slm_home: Path) -> None:
+    result = CliRunner().invoke(app, ["runs", "list", "--json"])
+
+    assert result.exit_code == 0, result.output
+    assert json.loads(result.output) == []