feat(phase-1): land Anthropic provider plugin (D4)

Phase 1 Day 2. Anthropic provider plugin code lands, plus contractVersion
field added across base.mjs and validated strictly. Anthropic stays
CANDIDATE per ALIGNMENT.md Provider Inventory — D5 flips to Enabled after
the real spawn E2E audit passes. POST /v1/chat/completions claude-* still
returns 503 until then.

Files:
  NEW:  lib/providers/anthropic.mjs (445 lines)
  MOD:  lib/providers/base.mjs (+8 lines — contractVersion enforcement)
  MOD:  lib/providers/index.mjs (+37 lines — STATIC_REGISTRY adds anthropic
        + getProviderByName helper)
  MOD:  models-registry.json — populates providers.anthropic with 3 models
        opus-4-7 / sonnet-4-6 / haiku-4-5, alias map, candidate marker
  MOD:  test-features.mjs (+481 lines — Suite 6: 37 new tests covering
        contract conformance, contractVersion enforcement, IR translation,
        mock-spawn behaviour, healthCheck, estimateCost)

Authority citations (all verified by independent reviewer against actual
OCP byte offsets):
  Spawn pattern: OCP server.mjs:542 stdio shape, port verbatim.
  CLI args: OCP server.mjs:384-414 buildCliArgs pattern — -p, --model X,
    --output-format text, --no-session-persistence (session-resume and
    permissions branches stripped per OLP no-state architecture).
  stdin write: OCP server.mjs:586-587 verbatim.
  Stdout text handling: OCP server.mjs:735-748 raw d.toString per chunk
    no JSON envelope, matches --output-format text.
  Auth chain: OCP server.mjs:864-888 (env CLAUDE_CODE_OAUTH_TOKEN ->
    ~/.claude/.credentials.json -> macOS keychain with both label formats
    "claude-code-credentials" and "Claude Code-credentials") ported in
    same priority order. One delta vs OCP: OLP guards keychain branch on
    process.platform === darwin, OCP relies on try/catch on Linux. Both
    behave identically; OLP avoids an unnecessary shell-out.
  Env cleanup: OCP server.mjs:530-534 — delete CLAUDECODE, ANTHROPIC_
    API_KEY, ANTHROPIC_BASE_URL, ANTHROPIC_AUTH_TOKEN. CLAUDECODE
    clobbering pitfall inherited per memory.

Architectural decisions:
  1. Anthropic stays Candidate at D4. STATIC_REGISTRY.length === 1 but
     loadProviders({}) returns empty Map. Suite 7 HTTP integration tests
     continue to verify 503 with no_enabled_provider for any claude-*
     model. D5 changes the config default to enable: { anthropic: true }
     and adds the real E2E spawn test.
  2. contractVersion === 1.0 strictly enforced (F3 fold-in from D3
     review). validateProvider in base.mjs rejects providers missing or
     having any other version string. Suite 6 includes 4 tests covering
     missing / 0.9 / 1.0 / undefined cases.
  3. quotaStatus returns null at D4 with a TODO comment pointing at the
     ALIGNMENT.md 2026-06-16 one-shot audit. Anthropic Agent SDK Credit
     pool balance API has not been pinned; verification scheduled for
     2026-06-16 per OLP one-shot audits.
  4. estimateCost returns shape but usd: null. Per-million-token rates
     not pinned at D4. Lands when models-registry.json gains a pricing
     field in a later phase.
  5. Lossy translations explicitly documented in anthropic.mjs file
     header per ADR 0003 § Lossy-translation documentation requirement.
     Includes response_format json_object (system-prompt augmented),
     top_p (no --top-p flag), tool_choice required (no flag), and
     request-level tools[] + assistant tool_calls + tool_call_id
     (text-in/text-out CLI cannot consume structured tool wire format).
     The tools[] documentation gap was a reviewer non-blocking finding;
     folded in this commit.

Mocking discipline: no real claude -p spawn in any D4 test. spawn-path
coverage uses __setSpawnImpl injection of fake child_process. No real
OAuth tokens or API keys in fixtures — all use placeholder strings
fake-oauth-token / fake-token. Auth path computed via
path.join(homedir(), .claude, .credentials.json), no hardcoded
/Users/<name> literal.

Reviewer chain (Iron Rule 10):
  Implementer: sonnet (general-purpose).
  Fresh-context reviewer: opus (ecc:code-reviewer). Verdict
    APPROVE_WITH_MINOR.
  Reviewer ran npm test (98/98 pass) and verified all five OCP citations
    at the actual byte offsets in /Users/taodeng/ocp/server.mjs. All
    citations confirmed accurate.

Reviewer non-blocking findings:
  1. tools[] and tool_calls lossy-translation undocumented — FOLDED IN
     this commit (anthropic.mjs header rewritten with full lossy list).
  2. with type json import attribute Node 20 compat — DEFERRED to CI
     verification. The syntax is stable on Node 20.10+ and the CI
     setup-node@v4 with node-version 20 resolves to latest 20.x. If
     CI Node 20 leg fails, mitigation is bump engines.node to >=20.10
     or swap both import-attribute lines for readFileSync + JSON.parse.
  3. CLI_NOT_FOUND error code declared but never thrown — DEFERRED to
     a future commit. Pure cosmetic; could distinguish ENOENT from
     generic spawn errors but no functional impact.

Test count: 61 -> 98 (+37 D4 tests).

Verification:
  node --check on all touched files: clean.
  npm test on Node 25.8.0: 98/98 pass in 209ms.
  Reviewer-run npm test independently: 98/98 pass.
  loadProviders({}) returns empty Map (verified by orchestrator and
    reviewer): Anthropic Candidate gate holds.
  hygiene grep: no personal names, no /Users/<name>/ literals, no real
    OAuth tokens or API keys.

Co-Authored-By: Claude Opus 4.7 (noreply@anthropic.com)

lib/providers/anthropic.mjs

@@ -0,0 +1,453 @@
+/**
+ * lib/providers/anthropic.mjs — Anthropic Claude provider plugin
+ *
+ * Authority: OLP ALIGNMENT.md § Authority 1 — anthropic plugin governed by
+ *   `claude -p` from `@anthropic-ai/claude-code`.
+ *   OCP server.mjs inherits cli.js 2.1.89 audit pin at fork (per ALIGNMENT.md
+ *   § Provider authority pins).
+ *
+ * Spawn pattern ported from:
+ *   OCP server.mjs:384-414  (buildCliArgs — -p / --model / --output-format / --no-session-persistence)
+ *   OCP server.mjs:480-607  (spawnClaudeProcess — env cleanup, spawn, stdin write)
+ *   OCP server.mjs:422-468  (messagesToPrompt — text serialization)
+ *
+ * Auth reading ported from:
+ *   OCP server.mjs:864-888  (getOAuthCredentials — env → .credentials.json → keychain)
+ *   OCP server.mjs:531-534  (env cleanup: delete ANTHROPIC_API_KEY, ANTHROPIC_BASE_URL,
+ *                             ANTHROPIC_AUTH_TOKEN before spawn)
+ *
+ * Contract version: 1.0 (ADR 0002 § "Provider contract (v1.0 interface)" + D4 contractVersion fold-in)
+ *
+ * Status at D4: CANDIDATE. Not yet Enabled per ALIGNMENT.md § Provider Inventory.
+ * The plugin is present in STATIC_REGISTRY but enabled: false is the default config.
+ * POST /v1/chat/completions continues to return 503 until D5 flips the enabled flag
+ * in ~/.olp/config.json after E2E audit passes.
+ *
+ * Lossy translations (per ADR 0003 § "Lossy-translation documentation requirement"):
+ *   - `response_format: json_object` — Anthropic `claude -p` does not natively honor this
+ *     field; a system-prompt augmentation is injected ("Reply with valid JSON only.").
+ *   - `top_p` — not mapped to a `claude -p` flag; dropped silently. `claude -p` does not
+ *     expose --top-p.
+ *   - `tool_choice: "required"` — not a `claude -p` flag; dropped.
+ *   - Request-level `tools[]` — `claude -p --output-format text` is a text-in/text-out
+ *     CLI and does not consume structured tool definitions on the wire. The array is
+ *     silently dropped; if a caller wants tool-use they should pre-prompt the model
+ *     about the tools in the system message. ALIGNMENT.md Rule 2 forbids inventing
+ *     a wire format Anthropic's CLI does not accept.
+ *   - Assistant-message `tool_calls` and `tool_call_id` (IR messages representing prior
+ *     turns where the assistant invoked a tool) — same reason as above; dropped.
+ *     If a multi-turn conversation includes tool-call history, the textual content is
+ *     preserved but the structured call metadata is lost.
+ *
+ * Quota status: null at D4. Anthropic does not expose a programmatic quota endpoint.
+ *   TODO(2026-06-16): one-shot audit per ALIGNMENT.md § One-shot Triggered Audits.
+ *   After 2026-06-15 Agent SDK Credit billing split takes effect, re-evaluate whether
+ *   a programmatic credit-pool balance API exists and pin it here if found.
+ */
+
+import { spawn as defaultSpawn } from 'node:child_process';
+import { execFileSync, 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_CLAUDE_BIN env takes priority, then falls back to 'claude' from PATH.
+// Ported from OCP server.mjs:87-123 (resolveClaude) — simplified for plugin
+// scope (OCP's multi-path nvm/fnm/asdf resolution is omitted; OLP plugins
+// use the simpler env-override-first pattern and rely on PATH for the rest).
+//
+// OCP server.mjs:88: if (process.env.CLAUDE_BIN) { ... return process.env.CLAUDE_BIN; }
+// OLP uses OLP_CLAUDE_BIN to avoid colliding with OCP's CLAUDE_BIN if both are
+// installed on the same machine.
+function resolveClaudeBin() {
+  return process.env.OLP_CLAUDE_BIN || 'claude';
+}
+
+// ── Auth artifact reading ─────────────────────────────────────────────────
+// Ported from OCP server.mjs:864-888 (getOAuthCredentials).
+// Priority order (matching OCP exactly):
+//   1. CLAUDE_CODE_OAUTH_TOKEN env var — explicit override, highest precedence
+//   2. ~/.claude/.credentials.json (Linux file-based path)
+//   3. macOS keychain via `security find-generic-password`
+//      Both label formats tried: "claude-code-credentials" and "Claude Code-credentials"
+//
+// Returns { accessToken, refreshToken?, expiresAt? } or null.
+// Throws nothing — null means "not found, try next".
+export function readAuthArtifact() {
+  // 1. Env var — OCP server.mjs:866-868
+  if (process.env.CLAUDE_CODE_OAUTH_TOKEN) {
+    return { accessToken: process.env.CLAUDE_CODE_OAUTH_TOKEN };
+  }
+
+  // 2. Linux/cross-platform file-based credentials — OCP server.mjs:871-875
+  // Note: OCP uses ~/.claude/.credentials.json (dot-prefix), not ~/.claude/credentials.json.
+  // This matches the actual path Claude Code writes to.
+  try {
+    const credPath = join(homedir(), '.claude', '.credentials.json');
+    const raw = readFileSync(credPath, 'utf8');
+    const creds = JSON.parse(raw);
+    if (creds?.claudeAiOauth?.accessToken) return creds.claudeAiOauth;
+  } catch { /* fall through */ }
+
+  // 3. macOS keychain — OCP server.mjs:877-885
+  // Only attempted on darwin to avoid shell-out overhead on other platforms.
+  if (process.platform === 'darwin') {
+    for (const label of ['claude-code-credentials', 'Claude Code-credentials']) {
+      try {
+        const raw = execFileSync('security', [
+          'find-generic-password', '-s', label, '-w',
+        ], { encoding: 'utf8', timeout: 5000 }).trim();
+        const creds = JSON.parse(raw);
+        if (creds?.claudeAiOauth?.accessToken) return creds.claudeAiOauth;
+      } catch { /* try next */ }
+    }
+  }
+
+  return null;
+}
+
+// ── IR → prompt text serialization ───────────────────────────────────────
+// OCP server.mjs:422-468 (messagesToPrompt) — no session management in OLP;
+// we always pass the full serialized messages as stdin to `claude -p`.
+//
+// `claude -p` reads its prompt from stdin when no prompt argument is given.
+// OCP server.mjs:542 confirms: `proc.stdin.write(prompt); proc.stdin.end();`
+// The format OCP uses is: system → "[System] <text>", assistant → "[Assistant] <text>",
+// user → raw text. We port the same format.
+//
+// ADR 0003 § Translation direction model: the plugin owns irToNative.
+export function irToAnthropic(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') {
+      parts.push(`[System] ${text}`);
+    } else if (msg.role === 'assistant') {
+      parts.push(`[Assistant] ${text}`);
+    } else if (msg.role === 'tool') {
+      // Tool result — pass as annotated user turn so the model knows it's a tool response.
+      const nameAnnotation = msg.name ? ` (${msg.name})` : '';
+      parts.push(`[Tool Result${nameAnnotation}] ${text}`);
+    } else {
+      // user
+      parts.push(text);
+    }
+  }
+
+  // Lossy: response_format json_object → system-prompt augmentation.
+  // ADR 0003 § Lossy-translation documentation requirement.
+  if (irRequest.response_format?.type === 'json_object') {
+    parts.unshift('[System] Reply with valid JSON only. Do not include any prose outside the JSON structure.');
+  }
+
+  return parts.join('\n\n');
+}
+
+// ── Anthropic SSE chunk → IR ResponseChunk ────────────────────────────────
+// `claude -p --output-format text` emits raw text to stdout (not NDJSON/SSE).
+// This matches OCP server.mjs:735-748: each `proc.stdout.on('data', d => ...)` chunk
+// is raw text content — no JSON envelope. The plugin converts raw text chunks to
+// IR delta chunks, and produces a synthetic stop chunk at close.
+//
+// For streaming: each text chunk → IRResponseChunk { type: 'delta', content: <text> }
+// For non-streaming: the full accumulated stdout → single text → emit delta + stop.
+//
+// `claude -p --output-format json` would emit a JSON envelope, but OCP uses `text`
+// (OCP server.mjs:385: "--output-format", "text"), so we port the same.
+export function anthropicChunkToIR(rawText, isFirstChunk = false) {
+  return {
+    type: 'delta',
+    ...(isFirstChunk && { role: 'assistant' }),
+    content: rawText,
+  };
+}
+
+// Synthesize the stop chunk (called at proc.on('close', ...) with code 0).
+export function anthropicStopToIR(finishReason = 'stop') {
+  return {
+    type: 'stop',
+    finish_reason: finishReason,
+  };
+}
+
+// ── CLI args builder ──────────────────────────────────────────────────────
+// Ported from OCP server.mjs:384-414 (buildCliArgs), stripped of session
+// management (OLP is stateless per AGENTS.md § "No conversation state").
+//
+// OCP server.mjs:385: const args = ["-p", "--model", cliModel, "--output-format", "text"];
+// OCP server.mjs:392: args.push("--no-session-persistence");  // when no sessionInfo
+// OCP server.mjs:395-400: --dangerously-skip-permissions or --allowedTools
+//
+// OLP variant: always --no-session-persistence (stateless). No permissions flags at D4.
+function buildCliArgs(model) {
+  return [
+    '-p',
+    '--model', model,
+    '--output-format', 'text',
+    '--no-session-persistence',
+  ];
+}
+
+// ── Env cleanup ───────────────────────────────────────────────────────────
+// OCP server.mjs:531-534: deletes ANTHROPIC_API_KEY, ANTHROPIC_BASE_URL,
+// ANTHROPIC_AUTH_TOKEN before spawn to prevent env-level override collisions
+// with the OAuth token the CLI manages internally.
+// OCP server.mjs:530: const env = { ...process.env };
+function buildSpawnEnv() {
+  const env = { ...process.env };
+  // OCP server.mjs:531: delete env.CLAUDECODE;
+  delete env.CLAUDECODE;
+  // OCP server.mjs:532: delete env.ANTHROPIC_API_KEY;
+  delete env.ANTHROPIC_API_KEY;
+  // OCP server.mjs:533: delete env.ANTHROPIC_BASE_URL;
+  delete env.ANTHROPIC_BASE_URL;
+  // OCP server.mjs:534: delete env.ANTHROPIC_AUTH_TOKEN;
+  delete env.ANTHROPIC_AUTH_TOKEN;
+  return env;
+}
+
+// ── Spawn function (core) ─────────────────────────────────────────────────
+// Returns an AsyncIterator<IRResponseChunk> per ADR 0002 § Provider contract.
+// `spawnImpl` is swappable for tests (dependency injection, no real binary needed).
+//
+// OCP server.mjs:542: const proc = spawn(CLAUDE, cliArgs, { env, stdio: ["pipe", "pipe", "pipe"] });
+// OCP server.mjs:586-587: proc.stdin.write(prompt); proc.stdin.end();
+async function* _spawnAndStream(irRequest, authContext, spawnImpl) {
+  const auth = authContext ?? readAuthArtifact();
+  if (!auth?.accessToken) {
+    throw new ProviderError(
+      'No Anthropic OAuth token found. Run `claude auth login` or set CLAUDE_CODE_OAUTH_TOKEN.',
+      'AUTH_MISSING',
+    );
+  }
+
+  const bin = resolveClaudeBin();
+  const args = buildCliArgs(irRequest.model);
+  const env = buildSpawnEnv();
+
+  // Inject OAuth token so the CLI can authenticate.
+  // OCP server.mjs:864-888: the token is read from keychain/.credentials.json/env
+  // and passed as CLAUDE_CODE_OAUTH_TOKEN for the spawn invocation.
+  // We set it explicitly here so the plugin is self-contained.
+  env.CLAUDE_CODE_OAUTH_TOKEN = auth.accessToken;
+
+  const prompt = irToAnthropic(irRequest);
+
+  // OCP server.mjs:542: spawn(CLAUDE, cliArgs, { env, stdio: ["pipe", "pipe", "pipe"] })
+  const proc = spawnImpl(bin, args, { env, stdio: ['pipe', 'pipe', 'pipe'] });
+
+  // OCP server.mjs:586-587: proc.stdin.write(prompt); proc.stdin.end();
+  proc.stdin.write(prompt);
+  proc.stdin.end();
+
+  // Yield IR chunks as they arrive from stdout.
+  let isFirstChunk = true;
+  let accumulatedStderr = '';
+
+  // Convert proc events to an async generator using a push-buffer + signal approach.
+  const chunks = [];
+  let done = false;
+  let exitCode = null;
+  let exitSignal = null;
+  let resolveNext = null;
+
+  function push(item) {
+    chunks.push(item);
+    if (resolveNext) {
+      const r = resolveNext;
+      resolveNext = null;
+      r();
+    }
+  }
+
+  proc.stdout.on('data', (d) => {
+    const text = d.toString();
+    push({ type: 'data', text });
+  });
+
+  proc.stderr.on('data', (d) => {
+    accumulatedStderr += d.toString();
+  });
+
+  proc.on('error', (err) => {
+    push({ type: 'error', err });
+  });
+
+  proc.on('close', (code, signal) => {
+    exitCode = code;
+    exitSignal = signal;
+    done = true;
+    push({ type: 'close' });
+  });
+
+  // Drain the chunk buffer
+  while (true) {
+    if (chunks.length === 0) {
+      if (done) break;
+      // Wait for the next event
+      await new Promise((resolve) => { resolveNext = resolve; });
+      continue;
+    }
+
+    const item = chunks.shift();
+
+    if (item.type === 'error') {
+      throw new ProviderError(`claude spawn error: ${item.err.message}`, 'SPAWN_FAILED');
+    }
+
+    if (item.type === 'close') {
+      break;
+    }
+
+    if (item.type === 'data') {
+      yield anthropicChunkToIR(item.text, isFirstChunk);
+      isFirstChunk = false;
+    }
+  }
+
+  // Process close
+  if (exitCode !== 0) {
+    const errMsg = accumulatedStderr.slice(0, 300) || `claude exit ${exitCode}`;
+    // Map known exit patterns to IR error chunk, then throw
+    throw new ProviderError(errMsg, 'SPAWN_FAILED');
+  }
+
+  // Normal exit: emit stop chunk
+  yield anthropicStopToIR('stop');
+}
+
+// ── spawn (public, contract method) ──────────────────────────────────────
+// The public spawn method conforms to ADR 0002 § Provider contract:
+//   spawn: async (irRequest, authContext) => AsyncIterator<ResponseChunk>
+//
+// The `_spawnImpl` field is the injection point for tests.
+// Tests set `anthropic._spawnImpl = mockSpawn` before calling `anthropic.spawn()`.
+let _spawnImpl = defaultSpawn;
+
+export async function* spawn(irRequest, authContext) {
+  yield* _spawnAndStream(irRequest, authContext, _spawnImpl);
+}
+
+// Test hook: allows tests to inject a mock spawn without importing child_process.
+// Set anthropic._spawnImpl = mockFn before calling spawn(); reset after.
+export { _spawnImpl };
+export function __setSpawnImpl(impl) { _spawnImpl = impl; }
+export function __resetSpawnImpl() { _spawnImpl = defaultSpawn; }
+
+// ── estimateCost ──────────────────────────────────────────────────────────
+// Best-effort token estimation using the chars/4 heuristic.
+// Basis: OpenAI Cookbook "How to count tokens" rule-of-thumb: ~4 characters per token
+// for English prose. This is approximate; actual tokenization differs per model.
+// Reference: https://cookbook.openai.com/examples/how_to_count_tokens_with_tiktoken
+//
+// usd: null at D4 — Anthropic per-million-token rates not yet pinned.
+// TODO: populate usd once rates are confirmed post-2026-06-15 billing-split 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;
+  }
+
+  // Rough output estimate: assume response is ~50% of input 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 D4
+  };
+}
+
+// ── quotaStatus ───────────────────────────────────────────────────────────
+// Returns null at D4. Anthropic does not expose a programmatic quota endpoint.
+// TODO(2026-06-16 one-shot audit per ALIGNMENT.md § One-shot Triggered Audits):
+// After the 2026-06-15 Agent SDK Credit billing-split takes effect, check whether
+// the Agent SDK Credit pool exposes a balance/usage API endpoint. If it does,
+// implement here and update this comment with the endpoint URL + version pin.
+export async function quotaStatus(_authContext) {
+  return null;
+}
+
+// ── healthCheck ───────────────────────────────────────────────────────────
+// Does NOT spawn a real claude -p request (deferred to D5 E2E audit).
+// Checks: (1) binary exists, (2) auth artifact exists.
+// Ported from OCP server.mjs:363-377 (checkAuth) — simplified to existence
+// checks only; no live execution (per D4 spec constraint).
+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: 'claude 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 = resolveClaudeBin();
+  if (bin !== 'claude') {
+    // Explicit path given — check directly
+    return existsSync(bin);
+  }
+  // 'claude' from PATH — use which
+  try {
+    execSync('which claude', { encoding: 'utf8', timeout: 3000, stdio: ['ignore', 'pipe', 'ignore'] });
+    return true;
+  } catch {
+    return false;
+  }
+}
+
+// ── Provider export ───────────────────────────────────────────────────────
+// Conforms to ADR 0002 § "Provider contract (v1.0 interface)" including D4
+// contractVersion fold-in per reviewer F3.
+
+import modelsRegistryRaw from '../../models-registry.json' with { type: 'json' };
+
+const _registryModels = (modelsRegistryRaw?.providers?.anthropic?.models ?? []).map(m => m.id);
+
+const anthropic = {
+  name: 'anthropic',
+  displayName: 'Anthropic Claude',
+  contractVersion: '1.0',
+  models: _registryModels,
+  auth: {
+    type: 'oauth',
+    storage: 'keychain',
+    // Portable path via os.homedir() per hygiene requirement
+    path: join(homedir(), '.claude', '.credentials.json'),
+    refresh: 'auto',
+  },
+  spawn,
+  estimateCost,
+  quotaStatus,
+  healthCheck,
+  hints: {
+    requiresTTY: false,
+    concurrentSpawnSafe: true,
+    maxConcurrent: 4,
+  },
+};
+
+export default anthropic;