feat(processes): inject session PI_* env vars into started processes

.changeset/late-lobsters-inject.md

@@ -0,0 +1,5 @@
+---
+"@aliou/pi-processes": patch
+---
+
+Inject the session `PI_*` variables (`PI_SESSION_ID`, `PI_SESSION_FILE`, `PI_PROVIDER`, `PI_MODEL`, `PI_REASONING_LEVEL`) into processes started via the `process` tool's `start` action, mirroring the environment pi's bash tool exposes.

extensions/processes/tools/start/index.test.ts

@@ -25,7 +25,13 @@ const processInfo: ProcessInfo = {
   errorMessage: null,
 };
 
-const ctx = { cwd: "/repo" } as ExtensionContext;
+const ctx = {
+  cwd: "/repo",
+  sessionManager: {
+    getSessionId: () => "session-123",
+    getSessionFile: () => "/tmp/session-123.jsonl",
+  },
+} as ExtensionContext;
 
 function createFakeRegistry(): NotificationRegistry {
   return createNotificationRegistry();
@@ -71,7 +77,12 @@ describe("executeStart", () => {
       registry,
     );
 
-    expect(start).toHaveBeenCalledWith("dev", "pnpm dev", "/repo");
+    expect(start).toHaveBeenCalledWith(
+      "dev",
+      "pnpm dev",
+      "/repo",
+      expect.anything(),
+    );
     expect(details.notify).toEqual({
       onSuccess: "turn",
       onFailure: "turn",
@@ -154,7 +165,12 @@ describe("executeStart", () => {
       registry,
     );
 
-    expect(start).toHaveBeenCalledWith("dev", "pnpm dev", "/explicit");
+    expect(start).toHaveBeenCalledWith(
+      "dev",
+      "pnpm dev",
+      "/explicit",
+      expect.anything(),
+    );
     expect(details.process.cwd).toBe("/explicit");
   });
 
@@ -174,7 +190,33 @@ describe("executeStart", () => {
       registry,
     );
 
-    expect(start).toHaveBeenCalledWith("dev", "pnpm dev", "/repo");
+    expect(start).toHaveBeenCalledWith(
+      "dev",
+      "pnpm dev",
+      "/repo",
+      expect.anything(),
+    );
+  });
+
+  it("starts with PI_* session variables injected into the child env", () => {
+    const start = vi.fn((..._args: unknown[]) => processInfo);
+    const manager = { start } as unknown as ProcessManager;
+    const registry = createFakeRegistry();
+
+    executeStart(
+      {
+        action: "start",
+        name: "dev",
+        command: "pnpm dev",
+      },
+      manager,
+      ctx,
+      registry,
+    );
+
+    const env = start.mock.calls[0]?.[3] as NodeJS.ProcessEnv;
+    expect(env.PI_SESSION_ID).toBe("session-123");
+    expect(env.PI_SESSION_FILE).toBe("/tmp/session-123.jsonl");
   });
 });
 

extensions/processes/tools/start/index.ts

@@ -5,6 +5,7 @@ import type { NotificationRegistry } from "../../notifications/registry";
 import { normalizeNotifyConfig } from "../notify";
 import type { ProcessesParamsType, StartDetails } from "../schema";
 import { formatMatcherForModel } from "../watch-format";
+import { buildSessionEnv } from "./session-env";
 
 export function executeStart(
   params: ProcessesParamsType,
@@ -23,7 +24,12 @@ export function executeStart(
   const notify = normalizeNotifyConfig(params.notify);
 
   const cwd = params.cwd ?? ctx.cwd;
-  const process = manager.start(params.name, params.command, cwd);
+  const process = manager.start(
+    params.name,
+    params.command,
+    cwd,
+    buildSessionEnv(ctx),
+  );
   notifications.register(process.id, notify);
 
   return {

extensions/processes/tools/start/session-env.test.ts

@@ -0,0 +1,62 @@
+import type { ExtensionContext } from "@earendil-works/pi-coding-agent";
+import { describe, expect, it } from "vitest";
+import { buildSessionEnv } from "./session-env";
+
+function makeCtx(overrides: Partial<ExtensionContext> = {}): ExtensionContext {
+  return {
+    sessionManager: {
+      getSessionId: () => "session-123",
+      getSessionFile: () => "/tmp/session-123.jsonl",
+    },
+    model: { provider: "neuralwatt", id: "glm-5.3-flash-flex" },
+    thinkingLevel: "high",
+    ...overrides,
+  } as unknown as ExtensionContext;
+}
+
+describe("buildSessionEnv", () => {
+  it("injects the same PI_* session variables as pi's bash tool", () => {
+    const env = buildSessionEnv(makeCtx());
+
+    expect(env.PI_SESSION_ID).toBe("session-123");
+    expect(env.PI_SESSION_FILE).toBe("/tmp/session-123.jsonl");
+    expect(env.PI_PROVIDER).toBe("neuralwatt");
+    expect(env.PI_MODEL).toBe("glm-5.3-flash-flex");
+    expect(env.PI_REASONING_LEVEL).toBe("high");
+  });
+
+  it("copies the parent environment instead of mutating process.env", () => {
+    const before = { ...process.env };
+    const env = buildSessionEnv(makeCtx());
+
+    env.PI_SESSION_ID = "changed";
+    expect({ ...process.env }).toEqual(before);
+    expect(env.PI_CODING_AGENT).toBe(process.env.PI_CODING_AGENT);
+  });
+
+  it("leaves PI_SESSION_FILE to the ambient env when the session has no file", () => {
+    const env = buildSessionEnv(
+      makeCtx({
+        sessionManager: {
+          getSessionId: () => "session-123",
+          getSessionFile: () => undefined,
+        },
+      } as unknown as Partial<ExtensionContext>),
+    );
+
+    expect(env.PI_SESSION_ID).toBe("session-123");
+    // Passthrough: an ambient value is not ours to replace.
+    expect(env.PI_SESSION_FILE).toBe(process.env.PI_SESSION_FILE);
+  });
+
+  it("leaves provider, model, and reasoning level to the ambient env when no model is set", () => {
+    const env = buildSessionEnv(
+      makeCtx({ model: undefined, thinkingLevel: undefined }),
+    );
+
+    expect(env.PI_SESSION_ID).toBe("session-123");
+    expect(env.PI_PROVIDER).toBe(process.env.PI_PROVIDER);
+    expect(env.PI_MODEL).toBe(process.env.PI_MODEL);
+    expect(env.PI_REASONING_LEVEL).toBe(process.env.PI_REASONING_LEVEL);
+  });
+});

extensions/processes/tools/start/session-env.ts

@@ -0,0 +1,18 @@
+import type { ExtensionContext } from "@earendil-works/pi-coding-agent";
+
+/**
+ * Env for a spawned process: the parent env plus the same PI_* session
+ * variables pi's bash tool exposes.
+ */
+export function buildSessionEnv(ctx: ExtensionContext): NodeJS.ProcessEnv {
+  const env = { ...process.env };
+  env.PI_SESSION_ID = ctx.sessionManager.getSessionId();
+  const sessionFile = ctx.sessionManager.getSessionFile();
+  if (sessionFile) env.PI_SESSION_FILE = sessionFile;
+  if (ctx.model) {
+    env.PI_PROVIDER = ctx.model.provider;
+    env.PI_MODEL = ctx.model.id;
+  }
+  if (ctx.thinkingLevel) env.PI_REASONING_LEVEL = ctx.thinkingLevel;
+  return env;
+}

src/manager/index.ts

@@ -54,8 +54,13 @@ export class ProcessManager {
     return () => this.events.off("event", listener);
   }
 
-  start(name: string, command: string, cwd: string): ProcessInfo {
-    const managed = this.runtime.start(name, command, cwd);
+  start(
+    name: string,
+    command: string,
+    cwd: string,
+    env?: NodeJS.ProcessEnv,
+  ): ProcessInfo {
+    const managed = this.runtime.start(name, command, cwd, env);
     return formatProcess(managed);
   }
 

src/manager/process-runtime-controller.ts

@@ -50,8 +50,18 @@ export class ProcessRuntimeController {
     this.getConfiguredShellPath = deps.getConfiguredShellPath;
   }
 
-  start(name: string, command: string, cwd: string): ManagedProcessRecord {
-    const child = spawnCommand(command, cwd, this.getConfiguredShellPath());
+  start(
+    name: string,
+    command: string,
+    cwd: string,
+    env?: NodeJS.ProcessEnv,
+  ): ManagedProcessRecord {
+    const child = spawnCommand(
+      command,
+      cwd,
+      this.getConfiguredShellPath(),
+      env,
+    );
     return this.register(name, command, cwd, child, {});
   }