feat: run qrate from PATH when qrate did not start Pi

README.md

@@ -10,6 +10,14 @@ uses `SYSTEM.md`, not the external-agent skill. The extension is not a qrate Lua
 not write archive cells: `qrate_stage_findings` only publishes drafts that the archivist may accept
 from qrate's existing Problems panel and Fixes menu.
 
+## Use it in your own Pi
+
+Inside qrate you install nothing: the Agent panel loads this package for you. To use the same tools
+in a Pi you installed yourself, you need qrate with its `qrate` command on `PATH` (check with
+`qrate version`; the [command-line guide](https://qrate.dvnl.work/docs/cli) covers each platform).
+Then load this package as a Pi extension and open your project in qrate. The tools call `qrate` from
+`PATH` and show up in qrate's Agent panel under the name `pi`; set `QRATE_AGENT` to use another.
+
 ## Development
 
 ```sh
@@ -20,6 +28,7 @@ npm test
 
 The runtime contract is qrate's `qrate agent` command. qrate starts Pi with `QRATE_CLI` (the
 `qrate-cli` shipped beside the app) and `QRATE_AGENT=pi`; each tool runs
-`$QRATE_CLI agent <command>` with its parameters as JSON on stdin. Exit `1` is a refusal with JSON
-on stdout, and any other failure reports the CLI's stderr. A change to that command's contract
+`$QRATE_CLI agent <command>` with its parameters as JSON on stdin. Without those variables the tools
+run `qrate` from `PATH` as `pi`. Exit `1` is a refusal with JSON on stdout, and any other failure
+reports the CLI's stderr. A change to that command's contract
 needs a new extension release and a new pin in qrate's `scripts/fetch-agent-runtime.*`.

src/cli.ts

@@ -18,16 +18,21 @@ function refusal(stdout: string): string {
   return detail ? `${code}: ${detail}` : code;
 }
 
-/** Runs `$QRATE_CLI agent <method>` with the params on stdin. qrate sets QRATE_CLI and QRATE_AGENT. */
+/**
+ * Runs `qrate agent <method>` with the params on stdin. qrate sets QRATE_CLI and QRATE_AGENT for
+ * its own Pi; a Pi you installed yourself finds `qrate` on PATH and is named `pi`.
+ */
 export async function callQrate(
   method: string,
   params: Record<string, unknown> | undefined,
   signal?: AbortSignal,
 ): Promise<unknown> {
-  const cli = process.env.QRATE_CLI;
-  if (!cli) throw new QrateError("qrate did not provide its CLI path");
-
-  const child = spawn(cli, ["agent", method.replaceAll("_", "-")], { signal, windowsHide: true });
+  const cli = process.env.QRATE_CLI || "qrate";
+  const child = spawn(cli, ["agent", method.replaceAll("_", "-")], {
+    signal,
+    windowsHide: true,
+    env: { ...process.env, QRATE_AGENT: process.env.QRATE_AGENT || "pi" },
+  });
   let stdout = "";
   let stderr = "";
   child.stdout.setEncoding("utf8").on("data", (chunk: string) => (stdout += chunk));
@@ -36,7 +41,9 @@ export async function callQrate(
   child.stdin.end(JSON.stringify(params ?? {}));
 
   const code = await new Promise<number | null>((resolve, reject) => {
-    child.on("error", (error) => reject(new QrateError(`qrate's CLI could not run: ${String(error)}`)));
+    child.on("error", (error) =>
+      reject(new QrateError(`could not run \`${cli}\`; install qrate and put its command on PATH: ${String(error)}`)),
+    );
     child.on("close", resolve);
   });
   if (code === 1) throw new QrateError(`qrate refused the request: ${refusal(stdout)}`);

test/cli.test.ts

@@ -47,9 +47,27 @@ describe("qrate CLI client", () => {
     expect(JSON.parse(child.input)).toEqual({ revision: 3, findings: [] });
   });
 
-  it("refuses to run without qrate's CLI path", async () => {
-    await expect(callQrate("overview", undefined)).rejects.toThrow(QrateError);
-    expect(spawn).not.toHaveBeenCalled();
+  it("finds qrate on PATH and names itself when qrate did not start it", async () => {
+    delete process.env.QRATE_AGENT;
+    spawn.mockReturnValue(fakeCli(0, "{}"));
+    await callQrate("overview", undefined);
+    expect(spawn.mock.calls[0]?.[0]).toBe("qrate");
+    expect(spawn.mock.calls[0]?.[2].env.QRATE_AGENT).toBe("pi");
+
+    process.env.QRATE_AGENT = "pi/review-2";
+    spawn.mockReturnValue(fakeCli(0, "{}"));
+    await callQrate("overview", undefined);
+    expect(spawn.mock.calls[1]?.[2].env.QRATE_AGENT).toBe("pi/review-2");
+    delete process.env.QRATE_AGENT;
+  });
+
+  it("says how to fix a command that is not installed", async () => {
+    const child = fakeCli(0, "");
+    spawn.mockReturnValue(child);
+    const call = callQrate("overview", undefined);
+    child.emit("error", new Error("spawn qrate ENOENT"));
+    await expect(call).rejects.toThrow(QrateError);
+    await expect(call).rejects.toThrow("put its command on PATH");
   });
 
   it("reports qrate's structured refusal code", async () => {