/**
 * lib/providers/codex.mjs — OpenAI Codex provider plugin
 *
 * Authority: OLP ALIGNMENT.md § Authority 1 — openai plugin governed by
 *   `codex exec --json` from `@openai/codex` CLI.
 *
 * Governing ADRs:
 *   ADR 0002 — Plugin architecture, Provider contract v1.0
 *   ADR 0003 — IR design, lossy-translation documentation requirement
 *   ADR 0006 — OpenAI Codex classified Tier D (permissive, Candidate eligible)
 *              Authority pin: Codex GitHub Discussion #8338 (maintainer
 *              confirmed permissive OSS-project posture; not a formal ToS
 *              blessing — see ADR 0006 § Classification table, row "OpenAI Codex").
 *
 * Status at D6: CANDIDATE. Not yet Enabled per ALIGNMENT.md § Provider Inventory.
 * The plugin is present in STATIC_REGISTRY but enabled: false is the default.
 * POST /v1/chat/completions returns 503 until D7 E2E audit passes and the
 * enabled flag is flipped in ~/.olp/config.json.
 *
 * ── Authority pin (D6) ──────────────────────────────────────────────────────
 *
 * Primary authority: Codex CLI reference page
 *   URL: https://developers.openai.com/codex/cli/reference
 *   Sections used:
 *     § "codex exec [flags] PROMPT" — exec subcommand syntax
 *     § "--json / --experimental-json" — NDJSON output flag
 *     § "--model, -m" — model override flag
 *     § "codex e [flags] PROMPT" — short-form alias
 *
 * Secondary authority (features page):
 *   URL: https://developers.openai.com/codex/cli/features
 *   Sections used:
 *     § "Supported Models" — gpt-5.5 as recommended frontier model,
 *       GPT-5.3-Codex-Spark as research-preview fast model
 *     § "Automation" — exec subcommand described for scripting
 *
 * Auth authority:
 *   URL: https://developers.openai.com/codex/cli/reference
 *   § "Authentication" — credentials stored in $CODEX_HOME (default: ~/.codex/)
 *   The exact auth.json field names (access_token, etc.) are not pinned by D6
 *   docs — see Assumption A4 below.
 *
 * ── Lossy translations (per ADR 0003 § Lossy-translation documentation) ────
 *
 *   - `top_p` — not mapped to a `codex exec` flag; dropped silently.
 *     The Codex CLI reference (§ flag list) does not expose --top-p.
 *     ALIGNMENT.md Rule 2 forbids inventing a flag not in the docs.
 *
 *   - `temperature` — not mapped; Codex CLI reference does not expose
 *     --temperature at the exec subcommand level. Dropped silently.
 *
 *   - `stop` (stop sequences) — not a `codex exec` flag; dropped.
 *
 *   - `max_tokens` — not a `codex exec` flag; dropped silently. The CLI
 *     does not expose a --max-tokens flag per the reference.
 *
 *   - `tools[]` + `tool_choice` — `codex exec --json` is a text-in / NDJSON-out
 *     CLI; structured tool definitions are not passed on the wire. Dropped.
 *     If a caller wants tool use, pre-prompt the model via system message.
 *     ALIGNMENT.md Rule 2 applies.
 *
 *   - Assistant-message `tool_calls` / `tool_call_id` (prior-turn metadata) —
 *     same reason as `tools[]`; structured metadata dropped, textual content
 *     preserved in prompt serialization.
 *
 *   - `response_format: json_object` — Codex CLI does not natively honor this
 *     field. A system-prompt augmentation is injected ("Reply with valid JSON
 *     only."), mirroring the Anthropic plugin's approach (ADR 0003 § Lossy).
 *
 * ── Codex NDJSON event type assumptions (D6) ────────────────────────────────
 *
 * The Codex CLI reference (§ "--json") states: "Outputs newline-delimited JSON
 * events rather than formatted text, enabling machine-readable progress
 * tracking." It does not enumerate specific event type schemas. D6 therefore
 * defines a defensive parsing convention (see codexChunkToIR) that:
 *   - Treats any line with a `content` string field as a delta event
 *   - Treats any line with `type === 'stop'` or `done === true` as a stop event
 *   - Treats any line with `error` field or `type === 'error'` as an error event
 *   - Silently ignores other events (progress, tool_call, shell, etc.)
 * D7 E2E will observe real events and correct this convention if wrong.
 *
 * ── Canonical Codex docs URLs (authority per ALIGNMENT.md Authority 1) ─────
 *   Reference: https://developers.openai.com/codex/cli/reference
 *   Features:  https://developers.openai.com/codex/cli/features
 *   Auth:      https://developers.openai.com/codex/auth/   (canonical for auth.json)
 *   Models:    https://developers.openai.com/codex/models  (canonical for accepted --model IDs)
 *
 * ── D6 spec assumptions (revised after D6 review-2) ─────────────────────────
 *
 * A1 (command shape — CONFIRMED): `codex exec --json --model <model> PROMPT`.
 *    Reference § "codex exec" states: "Use '-' to pipe the prompt from stdin."
 *    Stdin path uses `args.push('-')` followed by `proc.stdin.write(prompt)`.
 *    Earlier D6 draft used "no positional + write stdin" — corrected here per
 *    reviewer round-2 finding citing the canonical reference page.
 *
 * A2 (auth file — CONFIRMED): `~/.codex/auth.json` is the documented auth
 *    artifact path. Per https://developers.openai.com/codex/auth/ : "Codex
 *    caches login details locally in a plaintext file at ~/.codex/auth.json
 *    or in your OS-specific credential store." $CODEX_HOME env overrides the
 *    base dir. OPENAI_CODEX_AUTH_PATH overrides the full path for testing.
 *
 * A3 (access token field — UNPINNED, D7 will probe): Auth doc does not
 *    enumerate the JSON field name. Defensive try-order: `access_token`,
 *    `token`, `accessToken`. D7 captures the real auth.json after `codex login`
 *    and pins the field name; the others can be removed.
 *
 * A4 (NDJSON delta events — UNPINNED, D7 will probe): Reference docs say
 *    "Outputs newline-delimited JSON events" without enumerating event schemas.
 *    Defensive 4-shape parser: `content` field → delta, `type:'stop'` or
 *    `done:true` → stop, `type:'error'` or `error` field → error, anything else
 *    ignored. D7 captures real stdout and corrects codexChunkToIR if events
 *    use different field names.
 *
 * A5 (env override — CONFIRMED NOT APPLICABLE): The auth doc mentions
 *    `OPENAI_API_KEY` only as input to `codex login --with-api-key`
 *    (login-time, not runtime). The plugin does NOT inject any access-token
 *    env var into the spawn env. `codex exec` reads its auth artifact directly
 *    from $CODEX_HOME/auth.json or the OS credential store.
 *
 * ── Known D7 follow-ups (not bugs at D6, but to verify) ─────────────────────
 * - OS credential store / keyring path. Per auth doc, credentials may live in
 *   an OS-specific credential store rather than auth.json. The Anthropic plugin
 *   supports macOS keychain via `security find-generic-password`; the Codex
 *   equivalent is unknown without a real install. D7 will inspect the live
 *   `codex login` artifact and add keyring support if needed.
 * - Exact `access_token` field name (A3).
 * - Real NDJSON event schema (A4).
 */

import { spawn as defaultSpawn } from 'node:child_process';
import { execSync } from 'node:child_process';
import { existsSync, readFileSync } from 'node:fs';
import { join } from 'node:path';
import { homedir } from 'node:os';
import { ProviderError } from './base.mjs';

// ── Binary resolution ─────────────────────────────────────────────────────
// OLP_CODEX_BIN env takes priority, then falls back to 'codex' from PATH.
// Mirrors the OLP_CLAUDE_BIN pattern in anthropic.mjs (same env-override-first
// approach). Using OLP_CODEX_BIN to avoid colliding with any system-level
// CODEX_BIN if other tools use that name.
function resolveCodexBin() {
  return process.env.OLP_CODEX_BIN || 'codex';
}

// ── Auth artifact reading ─────────────────────────────────────────────────
// Reads the Codex auth artifact from disk.
//
// Auth authority: Codex CLI reference § "Authentication"
//   "Credentials are stored in $CODEX_HOME (typically ~/.codex/)"
//   CODEX_HOME default: ~/.codex/
//
// Priority order:
//   1. OPENAI_CODEX_AUTH_PATH env override — testing convenience + custom install
//   2. $CODEX_HOME/auth.json where CODEX_HOME = process.env.CODEX_HOME ?? ~/.codex/
//
// D6 assumption A2: auth file is named auth.json (unconfirmed — D7 will pin).
// D6 assumption A3: access token field is `access_token` or `token` (unconfirmed).
//
// ── D75 (v0.4.2) F1 — codex CLI v0.133.0 schema pin ─────────────────────────
//
// Real codex CLI v0.133.0 auth.json (verified empirically on PI231 / Mac mini,
// 2026-05-26 E2E session):
//
//   {
//     "auth_mode": "chatgpt",
//     "OPENAI_API_KEY": null | "<key>",
//     "tokens": {
//       "id_token":      "<JWT>",
//       "access_token":  "<opaque-or-JWT>",   <-- THIS is the access token
//       "refresh_token": "<opaque>",
//       "account_id":    "<uuid>"
//     },
//     "last_refresh":    "<ISO8601>"
//   }
//
// D6 assumption A3 originally tried `creds.access_token` at TOP level. Under
// codex v0.133.0 this field does not exist at the top level → readAuthArtifact()
// returned null even when the user had fully completed `codex login`. OLP then
// reported "auth artifact missing" via /health and `olp doctor`, and refused
// to spawn codex — false negative blocking the entire openai provider.
//
// Fix: prepend `creds?.tokens?.access_token` to the precedence chain. Keep all
// existing fallbacks unchanged so older codex CLI versions (pre-v0.133) and any
// future shape variants still resolve.
//
// Authority pin: codex CLI v0.133.0 source + on-disk auth.json captured during
// PI231 E2E. See D75 commit body for the verification transcript.
//
// Returns { accessToken: string } or null (never throws).
export function readAuthArtifact() {
  // 1. Explicit test override — always takes precedence.
  const authPathOverride = process.env.OPENAI_CODEX_AUTH_PATH;
  if (authPathOverride) {
    try {
      const raw = readFileSync(authPathOverride, 'utf8');
      const creds = JSON.parse(raw);
      // D75 F1: codex CLI v0.133.0 nests the token under `tokens.access_token`.
      // Preserve top-level fallbacks for backward / forward compat.
      const token = creds?.tokens?.access_token
        ?? creds?.access_token
        ?? creds?.token
        ?? creds?.accessToken;
      if (token && typeof token === 'string') return { accessToken: token };
    } catch { /* fall through */ }
    return null; // explicit path set but file missing / malformed
  }

  // 2. $CODEX_HOME/auth.json (default: ~/.codex/auth.json)
  // Codex CLI reference § "Authentication": credentials in $CODEX_HOME (default ~/.codex/).
  const codexHome = process.env.CODEX_HOME ?? join(homedir(), '.codex');
  const authPath = join(codexHome, 'auth.json');
  try {
    const raw = readFileSync(authPath, 'utf8');
    const creds = JSON.parse(raw);
    // D75 F1: codex CLI v0.133.0 nests the token under `tokens.access_token`.
    // Try the nested location FIRST, then fall back to legacy top-level fields.
    const token = creds?.tokens?.access_token
      ?? creds?.access_token
      ?? creds?.token
      ?? creds?.accessToken;
    if (token && typeof token === 'string') return { accessToken: token };
  } catch { /* file missing or malformed */ }

  return null;
}

// ── IR → prompt text serialization ───────────────────────────────────────
// Translates an IR request into the { args, prompt } shape that spawn() needs.
//
// Authority: Codex CLI reference § "codex exec [flags] PROMPT"
//   Prompt is the final positional argument to `codex exec`.
//   Multi-line or large prompts: passed via stdin when prompt contains newlines
//   (D6 assumption A1 — stdin fallback unconfirmed; D7 will verify).
//
// Message serialization mirrors anthropic.mjs's irToAnthropic() pattern:
//   system → "[System] <text>", assistant → "[Assistant] <text>",
//   tool → "[Tool Result] <text>", user → plain text.
//
// ADR 0003 § Translation direction model: the plugin owns irToNative.
export function irToCodex(irRequest) {
  const parts = [];

  for (const msg of irRequest.messages) {
    const text = typeof msg.content === 'string'
      ? msg.content
      : JSON.stringify(msg.content);

    if (msg.role === 'system') {
      // System prompt — annotate so the model understands context.
      parts.push(`[System] ${text}`);
    } else if (msg.role === 'assistant') {
      // Prior assistant turn — preserve for conversation context.
      // tool_calls / tool_call_id metadata dropped (lossy — see file header).
      parts.push(`[Assistant] ${text}`);
    } else if (msg.role === 'tool') {
      // Tool result turn — annotate with name if available.
      // Structured tool_call_id dropped (lossy — see file header).
      const nameAnnotation = msg.name ? ` (${msg.name})` : '';
      parts.push(`[Tool Result${nameAnnotation}] ${text}`);
    } else {
      // user role — plain text, no annotation.
      parts.push(text);
    }
  }

  // Lossy: response_format json_object → system-prompt augmentation.
  // Codex CLI does not natively honor response_format; inject a system message
  // to request JSON output. ADR 0003 § Lossy-translation documentation.
  if (irRequest.response_format?.type === 'json_object') {
    parts.unshift('[System] Reply with valid JSON only. Do not include any prose outside the JSON structure.');
  }

  const prompt = parts.join('\n\n');

  // Authority: Codex CLI reference § "codex exec [flags] PROMPT"
  //   https://developers.openai.com/codex/cli/reference
  //   --json / --experimental-json: "Print newline-delimited JSON events instead
  //     of formatted text"
  //   --model, -m: "Override the configured model for this run." Accepts the
  //     model string (e.g., gpt-5.5, gpt-5.4, gpt-5.3-codex).
  //   PROMPT: "Initial instruction for the task. Use '-' to pipe the prompt
  //     from stdin."
  //
  // ── D75 (v0.4.2) F2 — codex CLI v0.133.0 trusted-directory sandbox ─────────
  // codex CLI v0.133.0 added a trusted-directory sandbox: invocations outside
  // a git repo (or outside any directory explicitly trusted via
  // `codex config trusted-directories`) refuse with:
  //   "Not inside a trusted directory and --skip-git-repo-check was not specified."
  // and exit non-zero with zero NDJSON output → OLP surfaces SPAWN_FAILED with
  // no usable chunks → fallback engine advances to next hop unnecessarily.
  //
  // The CWD that OLP spawns from is typically the server install dir (`~/olp/`
  // on Pi231) which is a git repo on maintainer workstations but is NOT a git
  // repo on most operator hosts. We bypass the sandbox unconditionally because
  // OLP is the trusted caller (it is the operator's own server invoking its own
  // configured Codex subscription via the documented `codex exec` automation
  // entry point). The trusted-directory sandbox is a foot-gun safeguard for
  // interactive users; OLP's spawn is non-interactive and pre-authorized.
  //
  // Authority: codex CLI v0.133.0 release notes / `codex exec --help` output
  // documenting `--skip-git-repo-check`. Verified empirically on PI231 E2E
  // 2026-05-26.
  const args = [
    'exec',
    '--json',
    '--skip-git-repo-check',
    '--model', irRequest.model,
  ];

  // Prompt passing strategy:
  // Short prompts (no newlines) → final argv positional per CLI synopsis.
  // Multi-line prompts → pipe via stdin using the documented `-` positional
  // (reference: "Use '-' to pipe the prompt from stdin."). The earlier D6
  // draft assumed stdin worked with no positional; codex-d6 review caught
  // that the documented stdin trigger is the literal `-` positional.
  const useStdin = prompt.includes('\n');

  if (useStdin) {
    args.push('-');
  } else {
    args.push(prompt);
  }

  return { args, prompt, useStdin };
}

// ── Codex NDJSON chunk → IR ResponseChunk ────────────────────────────────
// Parses one NDJSON line emitted by `codex exec --json` into an IR ResponseChunk.
//
// D6 assumption A4 (event schema — unconfirmed, D7 will pin from real output):
//   Content/delta event: line with a `content` string field
//     → { type: 'delta', content: <string> }
//   Stop event: line with type === 'stop' OR done === true
//     → { type: 'stop', finish_reason: 'stop' }
//   Error event: line with type === 'error' OR error field present
//     → { type: 'error', error: <string> }
//   Other (progress, shell_exec, tool_call, etc.) → null (caller skips)
//
// Returns null for lines that should be silently ignored (progress events, etc.).
export function codexChunkToIR(rawNDJSONLine) {
  if (!rawNDJSONLine || !rawNDJSONLine.trim()) return null;

  let event;
  try {
    event = JSON.parse(rawNDJSONLine.trim());
  } catch {
    // Malformed JSON line — skip silently (alignment with Rule 2: don't invent)
    return null;
  }

  if (!event || typeof event !== 'object') return null;

  // ── D75 (v0.4.2) F3 — codex CLI v0.133.0 event shape pin ─────────────────
  // Real codex CLI v0.133.0 NDJSON event stream (verified empirically on PI231
  // / Mac mini, 2026-05-26 E2E session):
  //   {"type":"thread.started","thread_id":"019e..."}
  //   {"type":"turn.started"}
  //   {"type":"item.started","item":{"id":"item_0","type":"reasoning","text":""}}
  //   {"type":"item.completed","item":{"id":"item_0","type":"agent_message","text":"<response>"}}
  //   {"type":"turn.completed","usage":{"input_tokens":..,"output_tokens":..}}
  //
  // The D6 defensive parser recognized `content`/`delta`/`text` fields at the
  // top level and `type === 'stop'`/`done === true`. None of these match
  // v0.133.0's actual shape → every chunk was silently dropped → response body
  // had `content: null`. F3 adds three NEW recognizers (item.completed →
  // agent_message; turn.completed → stop; turn.failed → error) BEFORE the
  // legacy fallback chain. Legacy recognizers preserved for forward/backward
  // compat (older codex versions; future shape variants).

  // F3-a: agent_message item completion.
  // codex v0.133.0 emits assistant text as a single item.completed event whose
  // item.type is 'agent_message' and item.text carries the full text. There
  // are no incremental deltas — the entire response arrives in one chunk.
  if (event.type === 'item.completed'
      && event.item?.type === 'agent_message'
      && typeof event.item?.text === 'string') {
    return { type: 'delta', content: event.item.text };
  }

  // F3-b: turn completion → stop chunk.
  // codex v0.133.0 emits turn.completed with a usage block when the model
  // finishes. We map this to IR stop with finish_reason 'stop'.
  if (event.type === 'turn.completed') {
    return { type: 'stop', finish_reason: 'stop' };
  }

  // F3-c: turn failure → error chunk.
  // codex v0.133.0 emits turn.failed with an embedded error object when the
  // turn cannot complete. Extract a human-readable message for the IR error.
  if (event.type === 'turn.failed') {
    const errMsg = (typeof event.error === 'string')
      ? event.error
      : (event.error?.message ?? 'codex turn.failed');
    return { type: 'error', error: errMsg };
  }

  // ── Legacy/fallback recognizers (kept for backward + forward compat) ────
  // Error event: type === 'error' or error field present
  // A4: defensive — error shape unconfirmed; D7 will pin actual field names
  if (event.type === 'error' || (event.error && typeof event.error === 'string')) {
    const errMsg = event.error ?? event.message ?? 'codex error';
    return { type: 'error', error: errMsg };
  }

  // Stop event: type === 'stop' or done === true
  // A4: defensive — stop shape unconfirmed; D7 will pin whether 'done' field exists
  if (event.type === 'stop' || event.done === true) {
    return { type: 'stop', finish_reason: 'stop' };
  }

  // Delta/content event: has a content string field
  // A4: defensive — primary delta shape assumed from Codex CLI § --json docs
  if (typeof event.content === 'string') {
    return { type: 'delta', content: event.content };
  }

  // delta field (alternative shape): { type: 'delta', delta: '...' }
  // A4: defensive — alternative shape not confirmed; D7 will probe real stdout
  if (event.type === 'delta' && typeof event.delta === 'string') {
    return { type: 'delta', content: event.delta };
  }

  // Output_text event shape (possible alternative): { type: 'output_text', text: '...' }
  // A4: defensive — text field shape not confirmed; D7 will probe real stdout
  if (typeof event.text === 'string') {
    return { type: 'delta', content: event.text };
  }

  // All other event types (progress, shell_exec, tool_call, etc.) → ignore
  return null;
}

// ── CLI args builder + env setup ──────────────────────────────────────────
// Builds the spawn environment. We do NOT inject the auth token as an env var
// because the Codex CLI manages OAuth state in its own auth.json file
// (CLI reference § "Authentication"). We simply ensure env is clean.
function buildSpawnEnv() {
  const env = { ...process.env };
  // Propagate CODEX_HOME if set (auth path resolution uses it).
  // Clean up any conflicting OpenAI env vars that might override CLI behavior.
  // No specific deletions confirmed needed at D6; conservative cleanup mirrors
  // anthropic.mjs pattern.
  return env;
}

// ── Spawn function (core) ─────────────────────────────────────────────────
// Returns an AsyncIterator<IRResponseChunk> per ADR 0002 § Provider contract.
//
// Spawn pattern:
//   1. Resolve binary via OLP_CODEX_BIN env or PATH 'codex'
//   2. Build args via irToCodex() → ['exec', '--json', '--model', <model>, <prompt>?]
//   3. Spawn with stdio: ['pipe', 'pipe', 'pipe']
//   4. If useStdin: write prompt to proc.stdin, end stdin
//   5. Parse each stdout line as NDJSON via codexChunkToIR()
//   6. On non-zero exit: throw ProviderError('SPAWN_FAILED')
//   7. On normal exit: emit stop chunk if not already emitted
//
// Authority: Codex CLI reference § "codex exec [flags] PROMPT"
//   § "--json": NDJSON event stream on stdout
async function* _spawnAndStream(irRequest, authContext, spawnImpl, isolationCtx) {
  const auth = authContext ?? readAuthArtifact();
  if (!auth?.accessToken) {
    throw new ProviderError(
      'No OpenAI Codex auth token found. Run `codex login` or set OPENAI_CODEX_AUTH_PATH.',
      'AUTH_MISSING',
    );
  }

  const bin = resolveCodexBin();
  const { args: baseArgs, prompt, useStdin } = irToCodex(irRequest);
  const env = buildSpawnEnv();

  // Authority: Codex CLI reference § "Authentication"
  //   CODEX_HOME propagated from env for auth file resolution.
  //   No explicit token injection: Codex CLI reads its own auth.json
  //   (contrast with Anthropic plugin which injects CLAUDE_CODE_OAUTH_TOKEN).

  // Task #8 — Phase 7 Solution 1: apply isolation context from orchestrator.
  // isolationCtx is provided by server.mjs (prepareIsolatedEnvironment) when
  // present. Three layers compose here:
  //   Layer 1 (env): envOverrides (HOME, CODEX_HOME) have final precedence.
  //   Layer 4 (args): hardenedArgs injects --sandbox read-only + -c approval_policy.
  //   Layer 3 (wrap): wrapForLayer3 is identity for codex (hasInnerSandbox=true).
  // When isolationCtx is absent (legacy callers / tests), behavior is unchanged.
  // Authority: ADR 0014 Amendment 1 § A1.2 + ADR 0002 Amendment 9 § Backward compat.
  const envOverrides = isolationCtx?.envOverrides ?? {};
  const finalEnv = Object.keys(envOverrides).length > 0 ? { ...env, ...envOverrides } : env;

  const hardenedArgs = isolationCtx?.hardenedArgs ?? ((a) => a);
  const args = hardenedArgs(baseArgs);

  // Layer 3: wrapForLayer3 for codex is always identity (hasInnerSandbox=true);
  // included here for API symmetry with the anthropic path and future-proofing.
  const wrapForLayer3 = isolationCtx?.wrapForLayer3 ?? (async (c) => c);
  const wrappedBin = await wrapForLayer3(bin);
  let finalBin, finalArgs;
  if (wrappedBin !== bin) {
    finalBin = '/bin/sh';
    finalArgs = ['-c', wrappedBin];
  } else {
    finalBin = bin;
    finalArgs = args;
  }

  const proc = spawnImpl(finalBin, finalArgs, { env: finalEnv, stdio: ['pipe', 'pipe', 'pipe'] });

  // Guard stdin writes against EPIPE (child may close stdin before we finish
  // writing — e.g. on auth error, bad model, or oversized prompt).
  // Port of OCP server.mjs:780.
  // Authority: Codex CLI reference (https://developers.openai.com/codex/cli/reference)
  // observed behaviour — fast-failing spawn closes stdin before OLP finishes writing.
  // ALIGNMENT.md Rule 2: no CLI operation changed; guard is a Node stream safety net.
  // The typeof guard protects test-injected mock stdin objects that are plain
  // objects (not EventEmitters) and do not implement .on().
  if (typeof proc.stdin.on === 'function') {
    proc.stdin.on('error', (e) => {
      console.error(JSON.stringify({ ts: new Date().toISOString(), level: 'warn', event: 'stdin_write_error', error: e.message }));
    });
  }
  // Write prompt via stdin for multi-line prompts (D6 assumption A1)
  if (useStdin) {
    proc.stdin.write(prompt);
  }
  proc.stdin.end();

  // Yield IR chunks as they arrive — push-buffer + signal pattern
  // (mirrors anthropic.mjs _spawnAndStream, same approach).
  const chunks = [];
  let done = false;
  let exitCode = null;
  let accumulatedStderr = '';
  let stopEmitted = false;
  let resolveNext = null;
  // timeout: tracks a pending rejectNext for spawn timeout
  let rejectNext = null;

  function push(item) {
    chunks.push(item);
    if (resolveNext) {
      const r = resolveNext;
      resolveNext = null;
      rejectNext = null;
      r();
    }
  }

  // Buffer stdout by line for NDJSON parsing.
  // Codex --json emits one JSON object per line (NDJSON convention).
  let stdoutBuf = '';
  proc.stdout.on('data', (d) => {
    stdoutBuf += d.toString();
    // Split on newlines; incomplete last segment stays in buffer.
    const lines = stdoutBuf.split('\n');
    stdoutBuf = lines.pop(); // last segment (possibly incomplete)
    for (const line of lines) {
      if (line.trim()) {
        push({ type: 'ndjson_line', line });
      }
    }
  });

  proc.stdout.on('end', () => {
    // Flush any remaining buffered content (line without trailing newline)
    if (stdoutBuf.trim()) {
      push({ type: 'ndjson_line', line: stdoutBuf.trim() });
      stdoutBuf = '';
    }
  });

  proc.stderr.on('data', (d) => {
    accumulatedStderr += d.toString();
  });

  proc.on('error', (err) => {
    push({ type: 'error', err });
  });

  proc.on('close', (code, _signal) => {
    exitCode = code;
    done = true;
    push({ type: 'close' });
  });

  // ADR 0004 § Trigger taxonomy bullet 4: spawn timeout is a hard trigger.
  // maxSpawnTimeMs: from hints field so tests can lower it without changing the plugin.
  // Default: 600 000 ms (10 minutes) — reasonable for long Codex outputs.
  const maxSpawnTimeMs = codex.hints?.maxSpawnTimeMs ?? 600_000;

  let spawnTimedOut = false;
  const spawnDeadlineTimer = setTimeout(() => {
    spawnTimedOut = true;
    try { proc.kill('SIGTERM'); } catch { /* ignore */ }
    if (rejectNext) {
      const r = rejectNext;
      rejectNext = null;
      resolveNext = null;
      r(new ProviderError(
        `codex spawn timed out after ${maxSpawnTimeMs}ms`,
        'SPAWN_TIMEOUT',
      ));
    }
  }, maxSpawnTimeMs);

  // Drain the chunk buffer
  let isFirstChunk = true;
  try {
    while (true) {
      if (chunks.length === 0) {
        if (done) break;
        if (spawnTimedOut) {
          throw new ProviderError(
            `codex spawn timed out after ${maxSpawnTimeMs}ms`,
            'SPAWN_TIMEOUT',
          );
        }
        await new Promise((resolve, reject) => {
          resolveNext = resolve;
          rejectNext = reject;
        });
        continue;
      }

      const item = chunks.shift();

      if (item.type === 'error') {
        throw new ProviderError(`codex spawn error: ${item.err.message}`, 'SPAWN_FAILED');
      }

      if (item.type === 'close') {
        break;
      }

      if (item.type === 'ndjson_line') {
        const irChunk = codexChunkToIR(item.line);
        if (irChunk === null) continue; // ignored event type (progress, etc.)

        if (irChunk.type === 'error') {
          // D26 round-3 F17: include accumulated stderr tail in the SPAWN_FAILED
          // message so the consumer-side collectAllChunks re-raises with full
          // context. ADR 0004 § Chain advancement step 4 (preserve debug signal).
          const stderrTail = accumulatedStderr.slice(0, 200);
          const errMsg = stderrTail
            ? `${irChunk.error} | stderr: ${stderrTail}`
            : irChunk.error;
          throw new ProviderError(errMsg, 'SPAWN_FAILED');
        }

        if (irChunk.type === 'stop') {
          stopEmitted = true;
          yield irChunk;
          continue;
        }

        if (irChunk.type === 'delta') {
          // Add role to first delta chunk (matching anthropic.mjs pattern)
          if (isFirstChunk) {
            yield { type: 'delta', role: 'assistant', content: irChunk.content };
            isFirstChunk = false;
          } else {
            yield irChunk;
          }
        }
      }
    }
  } finally {
    clearTimeout(spawnDeadlineTimer);
  }

  // D24 round-2 F4 fix: if the timer fired while the drain loop was processing
  // queued items, rejectNext was null at fire-time so the rejection was skipped.
  // The post-loop SPAWN_FAILED + yield-stop guards both check !spawnTimedOut, so
  // the generator would otherwise return normally with partial chunks despite the
  // timeout. This unconditional throw closes the race — SPAWN_TIMEOUT always
  // surfaces as a hard trigger to the fallback engine regardless of which path
  // the timer fire took. Note: any partial chunks already yielded are discarded
  // by the caller; SPAWN_TIMEOUT salvage parity is tracked in issue #3.
  if (spawnTimedOut) {
    throw new ProviderError(
      `codex spawn timed out after ${maxSpawnTimeMs}ms`,
      'SPAWN_TIMEOUT',
    );
  }

  // Process close
  if (exitCode !== 0 && !spawnTimedOut) {
    const errMsg = accumulatedStderr.slice(0, 300) || `codex exit ${exitCode}`;
    throw new ProviderError(errMsg, 'SPAWN_FAILED');
  }

  // Normal exit: emit stop chunk if the NDJSON stream didn't already emit one.
  if (!spawnTimedOut && !stopEmitted) {
    yield { type: 'stop', finish_reason: 'stop' };
  }
}

// ── spawn (public, contract method) ──────────────────────────────────────
// Public spawn conforms to ADR 0002 § Provider contract:
//   spawn: async (irRequest, authContext) => AsyncIterator<ResponseChunk>
let _spawnImpl = defaultSpawn;

// Task #8 — Phase 7 Solution 1: isolationCtx is an optional third argument.
// When present (from server.mjs prepareIsolatedEnvironment call), it carries
// { envOverrides, hardenedArgs, wrapForLayer3, cleanup } — the orchestrator
// composes these on top of the provider's own env-cleanup + args composition.
// When absent (legacy callers, tests that don't pass it), behavior is unchanged.
// Authority: ADR 0014 Amendment 1 § A1.2.
export async function* spawn(irRequest, authContext, isolationCtx) {
  yield* _spawnAndStream(irRequest, authContext, _spawnImpl, isolationCtx);
}

// Test hook: inject mock spawn without importing child_process.
export { _spawnImpl };
export function __setSpawnImpl(impl) { _spawnImpl = impl; }
export function __resetSpawnImpl() { _spawnImpl = defaultSpawn; }

// ── estimateCost ──────────────────────────────────────────────────────────
// Best-effort token estimation using chars/4 heuristic.
// Basis: OpenAI Cookbook "How to count tokens" rule-of-thumb: ~4 chars/token.
// Reference: https://cookbook.openai.com/examples/how_to_count_tokens_with_tiktoken
//
// usd: null at D6 — ChatGPT plan token-cost rates not yet pinned for Codex.
// TODO: populate usd once rates are confirmed post-D7 E2E billing audit.
export function estimateCost(request) {
  if (!request?.messages) return null;

  let inputChars = 0;
  for (const msg of request.messages) {
    const text = typeof msg.content === 'string'
      ? msg.content
      : JSON.stringify(msg.content);
    inputChars += text.length;
  }

  const outputCharsEstimate = Math.ceil(inputChars * 0.5);

  return {
    inputTokens: Math.ceil(inputChars / 4),
    outputTokensEstimate: Math.ceil(outputCharsEstimate / 4),
    currency: 'USD',
    usd: null, // not pinned at D6
  };
}

// ── quotaStatus ───────────────────────────────────────────────────────────
// Returns null at D6. ChatGPT plan limits are not exposed via a programmatic
// endpoint accessible from the CLI tier. If an API endpoint surfaces, pin it
// here with a docs URL (per ALIGNMENT.md Rule 1 authority-first requirement).
export async function quotaStatus(_authContext) {
  return null;
}

// ── healthCheck ───────────────────────────────────────────────────────────
// Does NOT spawn a real `codex exec` request (gated to D7 E2E).
// Checks: (1) `codex` binary exists on PATH, (2) auth artifact exists.
// Mirrors anthropic.mjs healthCheck pattern with injectable test overrides.
export async function healthCheck({ _binaryExistsFn, _authReadFn } = {}) {
  const t0 = Date.now();

  // 1. Binary check
  const binaryExists = _binaryExistsFn ?? _defaultBinaryExists;
  if (!binaryExists()) {
    return { ok: false, latencyMs: Date.now() - t0, error: 'codex binary not found' };
  }

  // 2. Auth artifact check
  const authRead = _authReadFn ?? readAuthArtifact;
  const auth = authRead();
  if (!auth?.accessToken) {
    return { ok: false, latencyMs: Date.now() - t0, error: 'auth artifact missing' };
  }

  return { ok: true, latencyMs: Date.now() - t0 };
}

function _defaultBinaryExists() {
  const bin = resolveCodexBin();
  if (bin !== 'codex') {
    // Explicit path given — check directly
    return existsSync(bin);
  }
  // 'codex' from PATH — use which
  try {
    execSync('which codex', { encoding: 'utf8', timeout: 3000, stdio: ['ignore', 'pipe', 'ignore'] });
    return true;
  } catch {
    return false;
  }
}

// ── doctorChecks (ADR 0002 Amendment 7, D67) ──────────────────────────────
// See lib/providers/anthropic.mjs doctorChecks header for the contract.
//
// Probes:
//   openai.cli_available    — `codex --version` resolves on PATH (or via OLP_CODEX_BIN)
//   openai.auth_present     — `readAuthArtifact()` returns a non-empty accessToken
//     (Codex CLI reference § Authentication: credentials in $CODEX_HOME, default ~/.codex/auth.json)
export function doctorChecks({ _binaryExistsFn, _authReadFn } = {}) {
  const binaryExists = _binaryExistsFn ?? _defaultBinaryExists;
  const authRead = _authReadFn ?? readAuthArtifact;
  return [
    {
      id: 'openai.cli_available',
      category: 'provider',
      async run() {
        if (binaryExists()) {
          return { status: 'ok', message: '`codex` binary resolved on PATH' };
        }
        return {
          status: 'fail',
          message: '`codex` binary not found on PATH (and OLP_CODEX_BIN unset/invalid)',
          evidence: {
            fix_commands: [
              'npm install -g @openai/codex',
            ],
            reference: 'https://developers.openai.com/codex/cli/reference',
          },
        };
      },
    },
    {
      id: 'openai.auth_present',
      category: 'provider',
      async run() {
        const auth = authRead();
        if (auth?.accessToken) {
          return { status: 'ok', message: 'Codex auth artifact present ($CODEX_HOME/auth.json)' };
        }
        return {
          status: 'fail',
          message: 'Codex auth artifact missing — $CODEX_HOME/auth.json does not contain access_token (default $CODEX_HOME=~/.codex)',
          evidence: {
            human_steps: [
              'run: codex  (the first interactive launch prompts for OAuth login per Codex CLI reference § Authentication)',
            ],
            reference: 'https://developers.openai.com/codex/cli/reference',
          },
        };
      },
    },
  ];
}

// ── ISOLATION export ─────────────────────────────────────────────────────
// Declares per-provider isolation primitives consumed by lib/sandbox/manager.mjs
// (per ADR 0014 Amendment 1 + ADR 0002 Amendment 9).
//
// Authority citations (all required per ALIGNMENT.md Rule 1):
//   codex CLI v0.133.0 — current PI231 prod version (verified 2026-05-29 spike)
//   https://developers.openai.com/codex/config-reference — CODEX_HOME env var
//     (2 occurrences verified: "$CODEX_HOME/profile-name.config.toml" and
//     "$CODEX_HOME/log" path templates)
//   https://developers.openai.com/codex/auth/ — ~/.codex/auth.json path
//     (2 occurrences verified: "auth.json under CODEX_HOME" credential-storage
//     section)
//   https://developers.openai.com/codex/concepts/sandboxing — --sandbox flag +
//     read-only default (codex inner bubblewrap sandbox)
//   openai/codex#16018 — inner bwrap behavior documented (failure under
//     restricted env, establishing hasInnerSandbox: true)
//   ADR 0014 Amendment 1 — orchestrator composition architecture
//   ADR 0002 Amendment 9 — ISOLATION contract spec (field semantics)
//   docs/spikes/2026-05-29-ephemeral-home.md § 5.3 — flag-drift caveat
//     (--ask-for-approval removed in codex v0.133.0; use -c approval_policy=)
//
// isolation rationale: OpenAI Codex's `codex exec` exposes a shell tool that
// actually executes commands during the spawn (cc-mem incident memory § 3.2).
// The CLI provides its own inner bubblewrap sandbox (`--sandbox read-only` by
// default per https://developers.openai.com/codex/concepts/sandboxing) that
// confines shell tool reads/writes. The orchestrator's outer isolation composes
// with the inner sandbox: credential-dir redirect via CODEX_HOME
// (https://developers.openai.com/codex/config-reference) + HOME redirect for
// the inner bwrap's HOME lookup + per-spawn ephemeral credential mount.
// hasInnerSandbox: true so the outer profile is relaxed to permit the inner
// bwrap's user-namespace clone (openai/codex#16018).

export const ISOLATION = {
  // ephemeralEnvOverrides: pure function, no side effects, no fs access.
  // CODEX_HOME redirects the entire codex config/credential base directory.
  // HOME is also redirected because the codex inner sandbox inherits the parent
  // process's HOME for its own home lookup unless overridden.
  // Authority: CODEX_HOME → https://developers.openai.com/codex/config-reference
  //            HOME → POSIX convention (both verified by PI231 spike § 4.3-4.4).
  ephemeralEnvOverrides: ({ ephemeralRoot, keyId: _keyId, reqId: _reqId }) => ({
    HOME: ephemeralRoot,
    CODEX_HOME: `${ephemeralRoot}/.codex`,
  }),

  // credentialMounts: static list of [srcAbsPath, dstRelativeToEphemeralRoot].
  // srcAbsPath uses os.homedir() (imported as `homedir` at top of file) per
  // ADR 0002 Amendment 9 § Field 2 validation rules: absolute paths only, no
  // `~/` prefixes (shell-expansion semantics differ from Node.js behavior).
  // Authority: ~/.codex/auth.json → https://developers.openai.com/codex/auth/
  //   "Codex caches login details locally in a plaintext file at ~/.codex/auth.json"
  //   (matches existing codex.mjs `auth.path` field declaration above).
  credentialMounts: [
    [join(homedir(), '.codex', 'auth.json'), '.codex/auth.json'],
  ],

  // requiredHomePaths: directories to mkdir-p under ephemeralRoot before mounts.
  // .codex is required because CODEX_HOME points there and codex startup may
  // attempt to read from it before any auto-create logic runs (observed in
  // PI231 spike § 4.3 post-state: .codex/ created at spawn time).
  requiredHomePaths: [
    '.codex',
  ],

  // hasInnerSandbox: true — codex exec spawns its own bubblewrap sandbox
  // internally. Declaring true tells the outer isolation orchestrator to relax
  // the outer profile to permit clone(CLONE_NEWUSER) so the inner bwrap can
  // create user namespaces. Without this flag the inner bwrap fails with
  // EPERM. Authority: openai/codex#16018 + https://developers.openai.com/codex/concepts/sandboxing
  hasInnerSandbox: true,

  // crossTenantReadProtection: 'inner-sandbox' — codex's shell tool runs real
  // commands but the inner bubblewrap sandbox (read-only by default) confines
  // reads/writes to the inner namespace. The toolHardeningArgs below makes this
  // default explicit at the spawn-args level. Authority: openai/codex#16018 +
  // https://developers.openai.com/codex/concepts/sandboxing.
  crossTenantReadProtection: 'inner-sandbox',

  // recommendedDeploymentTier: 'per-os-user' — the inner bwrap sandbox protects
  // against accidental cross-tenant leakage from the model's shell tool, but a
  // sandbox-escape CVE (e.g. in bubblewrap) would expose the OS-user filesystem.
  // Per-OS-user isolation adds defense in depth. See ADR 0002 Amendment 9
  // § Field 6 for the full rationale per recommendedDeploymentTier semantics.
  recommendedDeploymentTier: 'per-os-user',

  // toolHardeningArgs: injects --sandbox read-only if not already present, and
  // -c approval_policy="never" to suppress interactive approval prompts.
  //
  // Flag-drift caveat (docs/spikes/2026-05-29-ephemeral-home.md § 5.3):
  //   ADR 0002 Amendment 9 § codex example uses `--ask-for-approval never`.
  //   PI231 spike (2026-05-29) confirmed this flag was REMOVED in codex
  //   v0.133.0. The codex v0.133.0 `--help` output shows the replacement is
  //   the generic config-override flag: `-c approval_policy="never"`.
  //   We use `-c approval_policy="never"` here. This deviates from the ADR
  //   0002 Amendment 9 code example (not the field spec — the spec only
  //   requires an injected flag corresponding to a documented CLI flag).
  //   The config-override form is documented at https://developers.openai.com/codex/config-reference
  //   as the mechanism for overriding any config key at spawn time, including
  //   approval_policy. The deviation is intentional, flag-drift-driven, and
  //   takes precedence over the (now-incorrect) Amendment 9 code example per
  //   ALIGNMENT.md Rule 2 (provider CLI is the authority, not the ADR text).
  //
  // --sandbox read-only: Authority: https://developers.openai.com/codex/concepts/sandboxing
  //   § "Sandboxing modes" — the default posture is `read-only`; injecting it
  //   explicitly prevents a future codex default change from silently weakening
  //   isolation (same rationale as the existing irToCodex --skip-git-repo-check).
  toolHardeningArgs: (existingArgs) => {
    let result = [...existingArgs];

    // Inject --sandbox read-only if the caller has not already specified --sandbox.
    if (!result.some(arg => arg === '--sandbox' || arg.startsWith('--sandbox='))) {
      result = [...result, '--sandbox', 'read-only'];
    }

    // Inject -c approval_policy="never" if not already present.
    // Checks for the exact -c flag form used by codex v0.133.0 config overrides.
    // Flag-drift note: --ask-for-approval (pre-v0.133.0) is NOT injected — it
    // was removed; see header comment above.
    const approvalAlreadySet = result.some(
      (arg, i) => arg === '-c' && typeof result[i + 1] === 'string' && result[i + 1].startsWith('approval_policy'),
    );
    if (!approvalAlreadySet) {
      result = [...result, '-c', 'approval_policy="never"'];
    }

    return result;
  },
};

// ── Provider export ───────────────────────────────────────────────────────
// Conforms to ADR 0002 § "Provider contract (v1.0 interface)" + contractVersion.

import modelsRegistryRaw from '../../models-registry.json' with { type: 'json' };

const _registryModels = (modelsRegistryRaw?.providers?.openai?.models ?? []).map(m => m.id);

const codex = {
  name: 'openai',
  displayName: 'OpenAI Codex',
  contractVersion: '1.0',
  models: _registryModels,
  auth: {
    type: 'oauth',
    storage: 'file',
    // Auth authority: Codex CLI reference § "Authentication"
    // "Credentials stored in $CODEX_HOME (typically ~/.codex/)"
    // D6 assumption A2: auth file named auth.json (D7 will confirm).
    path: join(homedir(), '.codex', 'auth.json'),
    refresh: 'auto',
  },
  spawn,
  estimateCost,
  quotaStatus,
  healthCheck,
  // ADR 0002 Amendment 7 (D67): OPTIONAL doctorChecks() — consumed by `olp doctor`.
  doctorChecks: () => doctorChecks(),
  hints: {
    requiresTTY: false,         // codex exec runs headless (per CLI reference § exec)
    concurrentSpawnSafe: true,  // each invocation is independent
    maxConcurrent: 4,           // conservative default, same as anthropic
    // ADR 0004 § Trigger taxonomy bullet 4: spawn timeout is a hard trigger.
    // 600_000ms = 10 minutes. Tests can lower this by mutating codex.hints.maxSpawnTimeMs.
    maxSpawnTimeMs: 600_000,
    // ADR 0002 Amendment 3 (D23): explicitly cacheable (default true; named here for
    // readability and as a model for future plugins that may need cacheable: false).
    cacheable: true,
  },
};

export default codex;