diff --git a/plugins/codex/scripts/lib/app-server.mjs b/plugins/codex/scripts/lib/app-server.mjs
index 127c8376..263791e0 100644
--- a/plugins/codex/scripts/lib/app-server.mjs
+++ b/plugins/codex/scripts/lib/app-server.mjs
@@ -186,11 +186,16 @@ class SpawnedCodexAppServerClient extends AppServerClientBase {
   }
 
   async initialize() {
+    // Pin to cmd.exe on Windows (NOT $SHELL) so the .cmd shim for codex is
+    // resolved via PATHEXT but no MSYS path translation kicks in on Git Bash.
+    // The original code used `process.env.SHELL || true`, which under Git Bash
+    // mangled Windows-style command flags. On POSIX, codex is a JS shebang
+    // file so direct spawn (shell:false) works.
     this.proc = spawn("codex", ["app-server"], {
       cwd: this.cwd,
       env: this.options.env ?? process.env,
       stdio: ["pipe", "pipe", "pipe"],
-      shell: process.platform === "win32" ? (process.env.SHELL || true) : false,
+      shell: process.platform === "win32" ? "cmd.exe" : false,
       windowsHide: true
     });
 
diff --git a/plugins/codex/scripts/lib/codex.mjs b/plugins/codex/scripts/lib/codex.mjs
index f2fe88bd..baf4bd76 100644
--- a/plugins/codex/scripts/lib/codex.mjs
+++ b/plugins/codex/scripts/lib/codex.mjs
@@ -44,6 +44,17 @@ const TASK_THREAD_PREFIX = "Codex Companion Task";
 const DEFAULT_CONTINUE_PROMPT =
   "Continue from the current thread state. Pick the next highest-value step and follow through until the task is resolved.";
 
+// Permanent auth-fail patterns from the OpenAI API. The underlying Codex CLI's
+// app-server retries indefinitely on these, but they never recover without
+// re-authenticating, so we abort the captureTurn early.
+const PERMANENT_AUTH_ERROR_RE = /\b(?:401\s+Unauthorized|403\s+Forbidden|Missing\s+bearer|invalid\s+api\s+key|authentication[_-]?failed)\b/i;
+
+function isPermanentAuthError(error) {
+  if (!error) return false;
+  const message = typeof error === "string" ? error : (error.message ?? "");
+  return PERMANENT_AUTH_ERROR_RE.test(message);
+}
+
 function cleanCodexStderr(stderr) {
   return stderr
     .split(/\r?\n/)
@@ -531,6 +542,12 @@ function applyTurnNotification(state, message) {
     case "error":
       state.error = message.params.error;
       emitProgress(state.onProgress, `Codex error: ${message.params.error.message}`, "failed");
+      // Short-circuit on permanent auth failures so we don't waste API quota
+      // in the underlying CLI's reconnect loop (it retries 5x by default).
+      // 401/403 from OpenAI never recovers without re-authenticating.
+      if (isPermanentAuthError(message.params.error)) {
+        completeTurn(state, { id: state.turnId ?? "auth-failure", status: "failed" });
+      }
       break;
     case "turn/completed":
       if ((message.params.threadId ?? null) !== state.threadId) {
diff --git a/plugins/codex/scripts/lib/git.mjs b/plugins/codex/scripts/lib/git.mjs
index 1749cfc8..99328a70 100644
--- a/plugins/codex/scripts/lib/git.mjs
+++ b/plugins/codex/scripts/lib/git.mjs
@@ -140,6 +140,16 @@ export function resolveReviewTarget(cwd, options = {}) {
   const supportedScopes = new Set(["auto", "working-tree", "branch"]);
 
   if (baseRef) {
+    // Verify the ref exists locally before we kick off a Codex thread; without
+    // this check the user gets a confusing "Reconnecting..." API error several
+    // seconds later instead of the actual root cause (typo or unfetched ref).
+    const verify = git(cwd, ["rev-parse", "--verify", "--quiet", `${baseRef}^{commit}`]);
+    if (verify.status !== 0) {
+      throw new Error(
+        `Base ref "${baseRef}" does not resolve to a commit in this repository. ` +
+        `Did you mean a different branch, or do you need to fetch it first (e.g. \`git fetch origin ${baseRef}\`)?`
+      );
+    }
     return {
       mode: "branch",
       label: `branch diff against ${baseRef}`,
diff --git a/plugins/codex/scripts/lib/process.mjs b/plugins/codex/scripts/lib/process.mjs
index af28d1cf..eca6042d 100644
--- a/plugins/codex/scripts/lib/process.mjs
+++ b/plugins/codex/scripts/lib/process.mjs
@@ -2,6 +2,13 @@ import { spawnSync } from "node:child_process";
 import process from "node:process";
 
 export function runCommand(command, args = [], options = {}) {
+  // On Windows we MUST go through a shell to resolve npm-installed CLIs, which
+  // are .cmd shims (PATHEXT lookup is shell-only). The previous code used
+  // `process.env.SHELL || true`, which under Git Bash resolved to /usr/bin/bash
+  // and rewrote args like `/PID 123 /T /F` as Unix paths
+  // (`/c/Program Files/Git/PID 123 /T /F`), breaking taskkill. Pin to cmd.exe
+  // so we keep .cmd resolution but skip MSYS path translation. On POSIX
+  // shell:false is fine.
   const result = spawnSync(command, args, {
     cwd: options.cwd,
     env: options.env,
@@ -9,7 +16,7 @@ export function runCommand(command, args = [], options = {}) {
     input: options.input,
     maxBuffer: options.maxBuffer,
     stdio: options.stdio ?? "pipe",
-    shell: process.platform === "win32" ? (process.env.SHELL || true) : false,
+    shell: process.platform === "win32" ? "cmd.exe" : false,
     windowsHide: true
   });