core/cli: /config opens plyngent.toml and reloads

Add slash /config to edit the active config path in $EDITOR, then reload
providers/agent settings while keeping a valid provider/model selection.

README.md

@@ -124,6 +124,7 @@ Type `/help` in the REPL for the live list. Common ones:
 | `/stream` `/verbose` `/tools` `/rounds` | Toggles and limits |
 | `/retry` | Re-run incomplete last user turn (after error/cancel) |
 | `/provider` `/model` | Switch without restarting |
+| `/config` | Edit `plyngent.toml` in `$EDITOR` and reload |
 | `/quit` | Leave the REPL |
 
 User messages are saved immediately. On API error or Ctrl+C, partial assistant/tool output is discarded but the user message stays so `/retry` works after resume. Interactive auto-retry uses 10s / 20s / 30s delays.

src/plyngent/cli/slash.py

@@ -293,6 +293,35 @@ def edit_cmd(state: ReplState) -> None:
     click.echo(f"(edit) {len(text)} characters ready to send")
 
 
+@slash.command("config")
+@click.pass_obj
+def config_cmd(state: ReplState) -> None:
+    """Open plyngent.toml in ``$EDITOR``, then reload providers/agent settings.
+
+    Same file as ``plyngent config edit``. After the editor exits, config is
+    re-read; current provider/model are kept when still valid.
+    """
+    from plyngent import config as config_mod
+    from plyngent.cli.editor import open_in_editor
+
+    path = state.config.path
+    try:
+        open_in_editor(path)
+    except click.ClickException as exc:
+        click.echo(f"error: {exc}")
+        return
+    try:
+        state.reload_config_from_disk()
+    except (config_mod.ConfigFormatError, ValueError, OSError) as exc:
+        click.secho(f"error: config reload failed: {exc}", fg="red")
+        click.echo(f"config file: {path}")
+        return
+    if state.config.bad_providers:
+        names = ", ".join(sorted(state.config.bad_providers.keys()))
+        click.secho(f"warning: ignored bad providers: {names}", fg="yellow")
+    click.echo(f"config reloaded from {path}\nprovider={state.provider_name}  model={state.model}")
+
+
 @slash.command("status")
 @click.pass_obj
 def status_cmd(state: ReplState) -> None:

src/plyngent/cli/state.py

@@ -111,6 +111,39 @@ class ReplState:
         self.agent.messages = messages
         self.sync_display_flags()
 
+    def reload_config_from_disk(self) -> None:
+        """Re-read TOML config and re-bind provider/model when still valid."""
+        import click
+
+        from plyngent.cli.selection import select_model, select_provider
+        from plyngent.runtime import ProviderNotSupportedError
+        from plyngent.tools import set_path_denylist
+
+        self.config.reload()
+        set_path_denylist(self.config.agent_config.path_denylist or None)
+
+        preferred_provider = self.provider_name if self.provider_name in self.config.providers else None
+        preferred_model = self.model
+        try:
+            pname, provider = select_provider(
+                self.config.providers,
+                preferred=preferred_provider,
+                interactive=False,
+            )
+        except (click.ClickException, ProviderNotSupportedError) as exc:
+            msg = f"config reloaded but provider selection failed: {exc}"
+            raise ValueError(msg) from exc
+        try:
+            model_id = select_model(provider, preferred=preferred_model, interactive=False)
+        except click.ClickException:
+            # Previous model not on this provider; pick first listed or keep free-form.
+            model_id = next(iter(sorted(provider.models.keys()))) if provider.models else preferred_model
+
+        self.provider_name = pname
+        self.provider = provider
+        self.model = model_id
+        self.rebuild_client()
+
     def _set_workspace(self, path: Path) -> None:
         """Update REPL + tool workspace root."""
         resolved = path.expanduser().resolve()

src/plyngent/config/store.py

@@ -99,6 +99,11 @@ class ConfigStore:
         self._agent = _parse_agent(cast("dict[str, object]", raw.get("agent", {})))
         self._providers, self._bad_providers = _parse_providers(document)
 
+    @property
+    def path(self) -> Path:
+        """Filesystem path of the TOML config file."""
+        return self._path
+
     # -- database (read-only) --
 
     @property

tests/test_cli/test_repl_commands.py

@@ -173,6 +173,26 @@ async def test_rename_slash(state: ReplState) -> None:
     assert row.name == "my-chat"
 
 
+async def test_config_slash_reloads(
+    state: ReplState,
+    monkeypatch: pytest.MonkeyPatch,
+    capsys: pytest.CaptureFixture[str],
+) -> None:
+    path = state.config.path
+    assert path is not None
+    # Fixture ConfigStore may not have written the file yet.
+    state.config.write()
+
+    def fake_open(p: object, **_k: object) -> None:
+        assert str(p) == str(path)
+
+    monkeypatch.setattr("plyngent.cli.editor.open_in_editor", fake_open)
+    assert await handle_slash(state, "/config") is True
+    out = capsys.readouterr().out
+    assert "config reloaded" in out
+    assert state.provider_name
+
+
 async def test_model_switch_persists(state: ReplState) -> None:
     from plyngent.config.models import ModelConfig