fix(agent-codex): fix token double-counting and spawn error handling

- Remove additive cached_tokens/reasoning_tokens from cost calculation
  (they are subsets of input_tokens/output_tokens per OpenAI API convention)
- Wrap entire connect() body in try/catch so connecting flag resets if
  spawn() throws synchronously (EMFILE, ENOMEM)
- Add test for spawn-throws-synchronously recovery
- Update cost assertions to reflect correct non-additive token counting

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/plugins/agent-codex/src/app-server-client.test.ts

@@ -983,6 +983,27 @@ describe("CodexAppServerClient", () => {
       expect(client.isConnected).toBe(true);
       await closeClient(client, proc);
     });
+
+    it("resets connecting flag if spawn throws synchronously", async () => {
+      // Make spawn throw (e.g. EMFILE, ENOMEM)
+      mockSpawn.mockImplementationOnce(() => {
+        throw new Error("spawn EMFILE");
+      });
+
+      const client = new CodexAppServerClient({ requestTimeout: 500 });
+      await expect(client.connect()).rejects.toThrow("spawn EMFILE");
+
+      // connecting flag should be reset — a retry should not throw "already connecting"
+      const proc = createFakeProcess();
+      const connectPromise = client.connect();
+      await new Promise((r) => setTimeout(r, 10));
+      const initReq = findRequest(proc, "initialize");
+      proc.sendLine(JSON.stringify({ id: initReq!["id"], result: {} }));
+      await connectPromise;
+
+      expect(client.isConnected).toBe(true);
+      await closeClient(client, proc);
+    });
   });
 
   describe("readline cleanup on process exit/error", () => {

packages/plugins/agent-codex/src/app-server-client.ts

@@ -174,37 +174,34 @@ export class CodexAppServerClient extends EventEmitter {
 
     this.connecting = true;
 
-    this.process = spawn(this.binaryPath, ["app-server"], {
-      cwd: this.cwd,
-      env: this.env ? { ...process.env, ...this.env } : undefined,
-      stdio: ["pipe", "pipe", "pipe"],
-    });
-
-    if (!this.process.stdout || !this.process.stdin) {
-      this.connecting = false;
-      throw new Error("Failed to open stdio pipes for codex app-server");
-    }
-
-    // Drain stderr to prevent the child process from blocking when
-    // the pipe buffer fills up.
-    this.process.stderr?.resume();
-
-    // Set up line-based reading from stdout
-    this.readline = createInterface({ input: this.process.stdout });
-    this.readline.on("line", (line) => this.handleLine(line));
-
-    // Handle process exit
-    this.process.once("exit", (code, signal) => {
-      this.handleProcessExit(code, signal);
-    });
-
-    this.process.once("error", (err) => {
-      this.handleProcessError(err);
-    });
-
-    // Perform initialization handshake. On failure, clean up the spawned
-    // process so the caller doesn't need to call close() explicitly.
     try {
+      this.process = spawn(this.binaryPath, ["app-server"], {
+        cwd: this.cwd,
+        env: this.env ? { ...process.env, ...this.env } : undefined,
+        stdio: ["pipe", "pipe", "pipe"],
+      });
+
+      if (!this.process.stdout || !this.process.stdin) {
+        throw new Error("Failed to open stdio pipes for codex app-server");
+      }
+
+      // Drain stderr to prevent the child process from blocking when
+      // the pipe buffer fills up.
+      this.process.stderr?.resume();
+
+      // Set up line-based reading from stdout
+      this.readline = createInterface({ input: this.process.stdout });
+      this.readline.on("line", (line) => this.handleLine(line));
+
+      // Handle process exit
+      this.process.once("exit", (code, signal) => {
+        this.handleProcessExit(code, signal);
+      });
+
+      this.process.once("error", (err) => {
+        this.handleProcessError(err);
+      });
+
       await this.initialize();
     } catch (err) {
       this.connecting = false;

packages/plugins/agent-codex/src/index.test.ts

@@ -638,10 +638,11 @@ describe("getSessionInfo", () => {
     expect(result!.summary).toBe("Codex session (o3-mini)");
     expect(result!.summaryIsFallback).toBe(true);
     expect(result!.cost).toBeDefined();
-    // input: 1000 + 200 (cached) + 2000 + 0 = 3200
-    // output: 500 + 100 (reasoning) + 300 + 0 = 900
-    expect(result!.cost!.inputTokens).toBe(3200);
-    expect(result!.cost!.outputTokens).toBe(900);
+    // cached_tokens/reasoning_tokens are subsets, not additive
+    // input: 1000 + 2000 = 3000
+    // output: 500 + 300 = 800
+    expect(result!.cost!.inputTokens).toBe(3000);
+    expect(result!.cost!.outputTokens).toBe(800);
     expect(result!.cost!.estimatedCostUsd).toBeGreaterThan(0);
   });
 

packages/plugins/agent-codex/src/index.ts

@@ -443,9 +443,9 @@ function extractCodexCost(lines: CodexJsonlLine[]): CostEstimate | undefined {
   for (const line of lines) {
     if (line.type === "event_msg" && line.msg?.type === "token_count") {
       inputTokens += line.msg.input_tokens ?? 0;
-      inputTokens += line.msg.cached_tokens ?? 0;
+      // cached_tokens is a subset of input_tokens (not additive)
       outputTokens += line.msg.output_tokens ?? 0;
-      outputTokens += line.msg.reasoning_tokens ?? 0;
+      // reasoning_tokens is a subset of output_tokens (not additive)
     }
   }