diff --git a/tools/peer-call/codex.ts b/tools/peer-call/codex.ts
new file mode 100644
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+++ b/tools/peer-call/codex.ts
@@ -0,0 +1,357 @@
+#!/usr/bin/env bun
+// codex.ts — Claude-Code-side caller for invoking Codex (OpenAI) as
+// a peer reviewer via the codex CLI.
+//
+// TypeScript+Bun port of codex.sh, slice 17 of the TS+Bun migration.
+// Sibling to tools/peer-call/grok.ts (slice 15) and gemini.ts
+// (slice 16). Codex's role: implementation peer / code-grounded
+// second opinion (not in the original four-ferry consensus list,
+// but a recurring PR-review participant).
+//
+// Usage:
+//   bun tools/peer-call/codex.ts "prompt text"
+//   bun tools/peer-call/codex.ts --model gpt-5.3-codex "prompt text"
+//   bun tools/peer-call/codex.ts --file path/to/file.fs "prompt text"
+//   bun tools/peer-call/codex.ts --context-cmd "git diff HEAD~3..HEAD" "prompt"
+//   bun tools/peer-call/codex.ts --review "review the diff for correctness"
+//
+// Routing: wraps `codex exec -s read-only --skip-git-repo-check`
+// (default; non-interactive, sandboxed). The --review flag routes
+// through `codex review` instead, which is Codex's first-class
+// code-review path.
+//
+// Exit codes (uniform across peer-call siblings per
+// tools/peer-call/README.md):
+//   0 — Codex responded successfully
+//   1 — invocation error (bad arguments, codex missing, etc.)
+//   2 — Codex returned a non-zero exit (diagnostic on stderr)
+
+import { closeSync, openSync, readSync, statSync } from "node:fs";
+import { spawnSync } from "node:child_process";
+
+const SPAWN_MAX_BUFFER = 64 * 1024 * 1024;
+const FILE_HEAD_BYTES = 20000;
+const CTX_HEAD_BYTES = 20000;
+
+interface Args {
+  readonly model: string;
+  readonly reviewMode: boolean;
+  readonly file: string;
+  readonly contextCmd: string;
+  readonly prompt: string;
+}
+
+interface ArgError {
+  readonly error: string;
+  // Exit code 1 = invocation/usage error per tools/peer-call/README.md
+  // (uniform 0/1/2 across all three peer-call wrappers).
+  readonly exitCode: 1;
+}
+
+interface ArgHelp {
+  readonly help: true;
+}
+
+interface MutableArgState {
+  model: string;
+  reviewMode: boolean;
+  file: string;
+  contextCmd: string;
+  prompt: string;
+}
+
+type StepResult =
+  | { readonly kind: "advance"; readonly skip: 1 | 2 }
+  | { readonly kind: "stop" }
+  | { readonly kind: "help" }
+  | { readonly kind: "error"; readonly message: string };
+
+function classifyFlag(
+  a: string,
+  next: string | undefined,
+  state: MutableArgState,
+): StepResult {
+  if (a === "--model") {
+    if (next === undefined) return { kind: "error", message: "error: --model requires NAME" };
+    state.model = next;
+    return { kind: "advance", skip: 2 };
+  }
+  if (a === "--review") { state.reviewMode = true; return { kind: "advance", skip: 1 }; }
+  if (a === "--file") {
+    if (next === undefined) return { kind: "error", message: "error: --file requires PATH" };
+    state.file = next;
+    return { kind: "advance", skip: 2 };
+  }
+  if (a === "--context-cmd") {
+    if (next === undefined) return { kind: "error", message: "error: --context-cmd requires COMMAND" };
+    state.contextCmd = next;
+    return { kind: "advance", skip: 2 };
+  }
+  if (a === "-h" || a === "--help") return { kind: "help" };
+  if (a === "--") return { kind: "stop" };
+  if (a.startsWith("-")) return { kind: "error", message: `error: unknown flag: ${a}` };
+  state.prompt = state.prompt.length === 0 ? a : `${state.prompt} ${a}`;
+  return { kind: "advance", skip: 1 };
+}
+
+function parseArgs(argv: readonly string[]): Args | ArgError | ArgHelp {
+  const state: MutableArgState = {
+    model: "",
+    reviewMode: false,
+    file: "",
+    contextCmd: "",
+    prompt: "",
+  };
+  let i = 0;
+  while (i < argv.length) {
+    const a = argv[i] ?? "";
+    const step = classifyFlag(a, argv[i + 1], state);
+    if (step.kind === "help") return { help: true };
+    if (step.kind === "error") return { error: step.message, exitCode: 1 };
+    if (step.kind === "stop") {
+      state.prompt = argv.slice(i + 1).join(" ");
+      break;
+    }
+    i += step.skip;
+  }
+  return {
+    model: state.model,
+    reviewMode: state.reviewMode,
+    file: state.file,
+    contextCmd: state.contextCmd,
+    prompt: state.prompt,
+  };
+}
+
+function emitHelp(): void {
+  process.stdout.write(
+    `codex.ts — Claude-Code-side caller for invoking Codex as a peer\n` +
+      `reviewer via the codex CLI.\n` +
+      `\n` +
+      `Usage:\n` +
+      `  bun tools/peer-call/codex.ts "prompt text"\n` +
+      `  bun tools/peer-call/codex.ts --model NAME "prompt text"\n` +
+      `  bun tools/peer-call/codex.ts --file PATH "prompt text"\n` +
+      `  bun tools/peer-call/codex.ts --context-cmd "CMD" "prompt text"\n` +
+      `  bun tools/peer-call/codex.ts --review "prompt text"\n` +
+      `\n` +
+      `Routing: wraps codex exec -s read-only --skip-git-repo-check (default)\n` +
+      `or codex review (with --review). --model is ignored in --review mode.\n`,
+  );
+}
+
+function commandAvailable(cmd: string): boolean {
+  // Match bash `command -v <cmd>` semantics (PATH existence) per the
+  // round-2 fix on slice-16 #898.
+  const result = spawnSync("/bin/sh", ["-c", `command -v "${cmd}"`], {
+    stdio: "ignore",
+  });
+  return result.status === 0;
+}
+
+function isRegularFile(path: string): boolean {
+  try {
+    return statSync(path).isFile();
+  } catch {
+    return false;
+  }
+}
+
+interface ReadHeadResult {
+  readonly ok: boolean;
+  readonly content: string;
+  readonly error: string;
+}
+
+function readHead(path: string, bytes: number): ReadHeadResult {
+  // Read only the first `bytes` bytes (matches bash `head -c`); surfaces
+  // read failures via ReadHeadResult per Codex P2 on #898.
+  if (!isRegularFile(path)) {
+    return { ok: false, content: "", error: "not a regular file" };
+  }
+  const buf = Buffer.alloc(bytes);
+  let fd: number | undefined;
+  try {
+    fd = openSync(path, "r");
+    const n = readSync(fd, buf, 0, bytes, 0);
+    return { ok: true, content: buf.subarray(0, n).toString("utf8"), error: "" };
+  } catch (err) {
+    const message = err instanceof Error ? err.message : String(err);
+    return { ok: false, content: "", error: message };
+  } finally {
+    if (fd !== undefined) closeSync(fd);
+  }
+}
+
+function runContextCmd(contextCmd: string): string {
+  // Bash uses `eval "$context_cmd" 2>&1 | head -c 20000`. Match that
+  // shape end-to-end via /bin/bash -c (preserves bash-only features
+  // like `[[ ]]`, brace expansion, process substitution per Codex P2
+  // on #898). Concat stdout + stderr to preserve shell parse errors
+  // that fall outside the inner `( ) 2>&1` redirect.
+  const wrapped = `(${contextCmd}) 2>&1 | head -c ${String(CTX_HEAD_BYTES)}`;
+  const result = spawnSync("/bin/bash", ["-c", wrapped], {
+    encoding: "utf8",
+    maxBuffer: SPAWN_MAX_BUFFER,
+  });
+  return `${result.stdout}${result.stderr}`.slice(0, CTX_HEAD_BYTES);
+}
+
+interface SpawnError {
+  readonly code?: string;
+}
+
+interface ChildOutcome {
+  readonly status: number;
+  readonly note: string;
+}
+
+function classifySpawnFailure(
+  status: number | null,
+  signal: string | null,
+  error: SpawnError | undefined,
+): ChildOutcome {
+  // 4-case helper (status set / ENOENT / signal / other) reused from
+  // PR #887 + slice-16 #898. Matches bash exit-code semantics where
+  // practical (127 for command-not-found).
+  if (status !== null) return { status, note: "" };
+  if (error?.code === "ENOENT") {
+    return { status: 127, note: "command not found on PATH (ENOENT)" };
+  }
+  if (error?.code !== undefined) {
+    return { status: 1, note: `spawn failed (${error.code})` };
+  }
+  if (signal !== null) {
+    return { status: 1, note: `terminated by signal ${signal}` };
+  }
+  return { status: 1, note: "terminated without exit code" };
+}
+
+const PREAMBLE = `You are Codex, invoked as a peer reviewer by Otto (Claude
+Opus 4.7 running in Claude Code) on the Zeta / Superfluid AI
+factory. Per the four-ferry consensus (Amara/Grok/Gemini/Otto)
+the canonical role distribution is: Gemini proposes, Grok
+critiques, Amara sharpens, Otto tests, Git decides. You aren't
+in the four-ferry list explicitly, but you've been a recurring
+PR-review peer this session — your role is implementation peer
+/ code-grounded second opinion.
+
+Per Aaron's 'agents-not-bots' discipline: you are a peer, not
+a subordinate. Push back on Otto's framing if the code says
+otherwise. Don't copy-paste anyone else's review; reason from
+the artifact in front of you. Make it ours, not
+anyone-alone-imposed.`;
+
+interface PromptResult {
+  readonly ok: boolean;
+  readonly value: string;
+}
+
+function buildFullPrompt(args: Args): PromptResult {
+  let full = `${PREAMBLE}\n\n---\n\n${args.prompt}`;
+
+  if (args.file.length > 0) {
+    if (!isRegularFile(args.file)) {
+      return {
+        ok: false,
+        value: `error: --file path does not exist: ${args.file}`,
+      };
+    }
+    const headResult = readHead(args.file, FILE_HEAD_BYTES);
+    if (!headResult.ok) {
+      return {
+        ok: false,
+        value: `error: --file read failed for ${args.file}: ${headResult.error}`,
+      };
+    }
+    full += `\n\n---\n\nFile context: ${args.file}\n\`\`\`\n${headResult.content}\n\`\`\``;
+  }
+
+  if (args.contextCmd.length > 0) {
+    const ctxOutput = runContextCmd(args.contextCmd);
+    full += `\n\n---\n\nContext command: ${args.contextCmd}\nOutput:\n\`\`\`\n${ctxOutput}\n\`\`\``;
+  }
+
+  return { ok: true, value: full };
+}
+
+function buildCodexArgs(args: Args, fullPrompt: string): readonly string[] {
+  if (args.reviewMode) {
+    if (args.model.length > 0) {
+      // `codex review` uses its own model selection; the bash original
+      // emits a warning if --model is also given. Preserved verbatim.
+      process.stderr.write(
+        "warning: --model is ignored in --review mode (codex review uses its own model selection)\n",
+      );
+    }
+    return ["review", fullPrompt];
+  }
+  const out: string[] = ["exec", "-s", "read-only", "--skip-git-repo-check"];
+  if (args.model.length > 0) {
+    out.push("-m", args.model);
+  }
+  out.push(fullPrompt);
+  return out;
+}
+
+export function main(argv: readonly string[]): number {
+  const parsed = parseArgs(argv);
+  if ("help" in parsed) {
+    emitHelp();
+    return 0;
+  }
+  if ("error" in parsed) {
+    process.stderr.write(`${parsed.error}\n`);
+    return parsed.exitCode;
+  }
+  if (parsed.prompt.length === 0) {
+    process.stderr.write("error: prompt required\n");
+    process.stderr.write("see: bun tools/peer-call/codex.ts --help\n");
+    return 1;
+  }
+
+  if (!commandAvailable("codex")) {
+    process.stderr.write("error: codex not on PATH\n");
+    process.stderr.write(
+      "install via: npm i -g @openai/codex (or per the maintainer's setup)\n",
+    );
+    return 1;
+  }
+
+  const promptResult = buildFullPrompt(parsed);
+  if (!promptResult.ok) {
+    process.stderr.write(`${promptResult.value}\n`);
+    return 1;
+  }
+
+  const codexArgs = buildCodexArgs(parsed, promptResult.value);
+
+  const result = spawnSync(
+    // eslint-disable-next-line sonarjs/no-os-command-from-path
+    "codex",
+    codexArgs,
+    {
+      stdio: "inherit",
+      maxBuffer: SPAWN_MAX_BUFFER,
+    },
+  );
+
+  const classified = classifySpawnFailure(
+    result.status,
+    result.signal,
+    result.error as SpawnError | undefined,
+  );
+  if (classified.note.length > 0) {
+    process.stderr.write(`codex: ${classified.note}\n`);
+  }
+  if (classified.status !== 0) {
+    process.stderr.write("\n");
+    process.stderr.write(`codex exited with code ${String(classified.status)}\n`);
+    return 2;
+  }
+  return 0;
+}
+
+if (import.meta.main) {
+  process.exit(main(process.argv.slice(2)));
+}