POK-91: Fix pluck's broken file ops and import-time crash

CHANGELOG.md

@@ -566,6 +566,13 @@ Newest entries on top, within each tool.
 - Added end-to-end `get`/`set` round-trip characterization tests across all four
   formats so the dispatch → handler → load/save path is covered (the prior suite
   pinned only pure helpers + `--help`).
+- Made the default `get`/`diff` TOML *display* writer-free: it no longer calls the
+  `tomli-w` writer on a pure read (which failed in the `tomli-w`-absent venv), and
+  a bare scalar/list value now renders as JSON instead of crashing (`tomli_w.dumps`
+  requires a top-level table — `get config.toml a.scalar.path` used to raise). TOML
+  tables still render as TOML when the writer is present. Pinned the default
+  (non-`--json`) display path in the characterization tests, including with the
+  writer absent.
 
 ### 1.1.0 — 2026-06-26
 - Added the brand emoji 🪶 to the identity banner (`ICON` now wired into the parser).

pluck

@@ -704,8 +704,18 @@ def show_value(title: str, loaded: LoadedConfig, value: Any) -> None:
             text = json.dumps(value, indent=2, default=str)
             lexer = "json"
         elif loaded.format == ConfigFormat.TOML:
-            text = toml_writer().dumps(value).rstrip() or "(empty)"
-            lexer = "toml"
+            # Render as TOML only when we actually can: a bare scalar/list has no
+            # standalone TOML representation (a TOML document is always a table),
+            # and serializing a table back needs the optional tomli-w writer.
+            # Otherwise fall back to JSON — it needs no writer and reads fine for
+            # a `get`, so a pure read never requires tomli-w (stdlib tomllib does
+            # the reading).
+            if isinstance(value, dict) and tomli_w is not None:
+                text = tomli_w.dumps(value).rstrip() or "(empty)"
+                lexer = "toml"
+            else:
+                text = json.dumps(value, indent=2, default=str)
+                lexer = "json"
         else:
             text = str(value)
             lexer = "bash"

tests/test_tools_characterization.py

@@ -140,13 +140,45 @@ def _require_writer(fmt):
 
 @pytest.mark.parametrize("fmt", ["json", "env", "yaml", "toml"])
 def test_pluck_get_reads_value(tmp_path, fmt):
-    """`pluck get` resolves a path in every format (reading needs no writer)."""
+    """`pluck get` resolves a path in every format, via both output modes."""
     body, key, expected = _PLUCK_SAMPLES[fmt]
     cfg = tmp_path / f"config.{fmt}"
     cfg.write_text(body)
+    # machine-readable mode: exact value on stdout
     proc = _run_pluck("get", "--json", str(cfg), key)
     assert proc.returncode == 0, proc.stderr
     assert json.loads(proc.stdout) == expected
+    # default (rich panel) display mode must also succeed and show the value
+    proc = _run_pluck("get", str(cfg), key)
+    assert proc.returncode == 0, proc.stderr
+    assert str(expected) in proc.stdout
+
+
+def test_pluck_get_toml_display_needs_no_writer(tmp_path):
+    """Default (panel) `get` on TOML must not require the tomli-w *writer*.
+
+    Reading TOML uses stdlib ``tomllib``; only rendering the value back as TOML
+    needed ``tomli_w``. Simulate the writer's absence by shadowing it with a
+    module that fails to import, and assert a plain `get` (no ``--json``) still
+    succeeds — the exact tomli-w-absent venv this issue targets. (``--json``
+    renders via ``json.dumps`` and never needed the writer.)
+    """
+    shim = tmp_path / "no_writer"
+    shim.mkdir()
+    (shim / "tomli_w.py").write_text('raise ImportError("simulated: tomli-w absent")\n')
+    cfg = tmp_path / "config.toml"
+    cfg.write_text('model = "gpt-4o"\n[web]\nport = 8080\n')
+    env = {
+        **os.environ,
+        "NO_COLOR": "1",
+        "PYTHONPATH": str(shim) + os.pathsep + os.environ.get("PYTHONPATH", ""),
+    }
+    proc = subprocess.run(
+        [sys.executable, str(REPO_ROOT / "pluck"), "get", str(cfg), "web.port"],
+        capture_output=True, text=True, timeout=60, env=env,
+    )
+    assert proc.returncode == 0, proc.stderr
+    assert "8080" in proc.stdout
 
 
 @pytest.mark.parametrize("fmt", ["json", "env", "yaml", "toml"])