fix: resolve ProviderModelNotFoundError on non-Claude runtimes (#1156)

Extend resolve_model_ids to accept "omit" value: returns empty string
so non-Claude runtimes (OpenCode, Codex, Gemini, etc.) use their
configured default model instead of unresolvable Claude aliases.

- resolve_model_ids: "omit" short-circuits before alias resolution
- model_overrides still respected (checked first) for explicit IDs
- Installer sets resolve_model_ids: "omit" in ~/.gsd/defaults.json
  for non-Claude runtimes during install
- 4 new tests covering omit behavior and override passthrough
- Fix websearch test mocks for fs.writeSync output change (#1276)

Closes #1156

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

bin/install.js

@@ -4171,6 +4171,27 @@ function finishInstall(settingsPath, settings, statuslineCommand, shouldInstallS
     configureOpencodePermissions(isGlobal);
   }
 
+  // For non-Claude runtimes, set resolve_model_ids: "omit" in ~/.gsd/defaults.json
+  // so resolveModelInternal() returns '' instead of Claude aliases (opus/sonnet/haiku)
+  // that the runtime can't resolve. Users can still use model_overrides for explicit IDs.
+  // See #1156.
+  if (runtime !== 'claude') {
+    const gsdDir = path.join(os.homedir(), '.gsd');
+    const defaultsPath = path.join(gsdDir, 'defaults.json');
+    try {
+      fs.mkdirSync(gsdDir, { recursive: true });
+      let defaults = {};
+      try { defaults = JSON.parse(fs.readFileSync(defaultsPath, 'utf8')); } catch { /* new file */ }
+      if (defaults.resolve_model_ids !== 'omit') {
+        defaults.resolve_model_ids = 'omit';
+        fs.writeFileSync(defaultsPath, JSON.stringify(defaults, null, 2) + '\n');
+        console.log(`  ${green}✓${reset} Set resolve_model_ids: "omit" in ~/.gsd/defaults.json`);
+      }
+    } catch (e) {
+      console.log(`  ${yellow}⚠${reset} Could not write ~/.gsd/defaults.json: ${e.message}`);
+    }
+  }
+
   let program = 'Claude Code';
   if (runtime === 'opencode') program = 'OpenCode';
   if (runtime === 'gemini') program = 'Gemini';

get-shit-done/bin/lib/core.cjs

@@ -205,7 +205,7 @@ function loadConfig(cwd) {
     exa_search: false,
     text_mode: false, // when true, use plain-text numbered lists instead of AskUserQuestion menus
     sub_repos: [],
-    resolve_model_ids: false, // when true, resolve aliases (opus/sonnet/haiku) to full model IDs
+    resolve_model_ids: false, // false: return alias as-is | true: map to full Claude model ID | "omit": return '' (runtime uses its default)
     context_window: 200000, // default 200k; set to 1000000 for Opus/Sonnet 4.6 1M models
     phase_naming: 'sequential', // 'sequential' (default, auto-increment) or 'custom' (arbitrary string IDs)
   };
@@ -885,12 +885,20 @@ const MODEL_ALIAS_MAP = {
 function resolveModelInternal(cwd, agentType) {
   const config = loadConfig(cwd);
 
-  // Check per-agent override first
+  // Check per-agent override first — always respected regardless of resolve_model_ids.
+  // Users who set fully-qualified model IDs (e.g., "openai/gpt-5.4") get exactly that.
   const override = config.model_overrides?.[agentType];
   if (override) {
     return override;
   }
 
+  // resolve_model_ids: "omit" — return empty string so the runtime uses its configured
+  // default model. For non-Claude runtimes (OpenCode, Codex, etc.) that don't recognize
+  // Claude aliases (opus/sonnet/haiku/inherit). Set automatically during install. See #1156.
+  if (config.resolve_model_ids === 'omit') {
+    return '';
+  }
+
   // Fall back to profile lookup
   const profile = String(config.model_profile || 'balanced').toLowerCase();
   const agentModels = MODEL_PROFILES[agentType];
@@ -898,8 +906,8 @@ function resolveModelInternal(cwd, agentType) {
   if (profile === 'inherit') return 'inherit';
   const alias = agentModels[profile] || agentModels['balanced'] || 'sonnet';
 
-  // If resolve_model_ids is true, map alias to full model ID
-  // This prevents 404s when the Task tool passes aliases directly to the API
+  // resolve_model_ids: true — map alias to full Claude model ID
+  // Prevents 404s when the Task tool passes aliases directly to the API
   if (config.resolve_model_ids) {
     return MODEL_ALIAS_MAP[alias] || alias;
   }

tests/commands.test.cjs

@@ -1195,15 +1195,16 @@ describe('websearch command', () => {
   const { cmdWebsearch } = require('../get-shit-done/bin/lib/commands.cjs');
   let origFetch;
   let origApiKey;
-  let origStdoutWrite;
+  let origWriteSync;
   let captured;
 
   beforeEach(() => {
     origFetch = global.fetch;
     origApiKey = process.env.BRAVE_API_KEY;
-    origStdoutWrite = process.stdout.write;
+    origWriteSync = fs.writeSync;
     captured = '';
-    process.stdout.write = (chunk) => { captured += chunk; return true; };
+    // output() uses fs.writeSync(1, data) since #1276 — mock it to capture output
+    fs.writeSync = (fd, data) => { if (fd === 1) captured += data; return Buffer.byteLength(String(data)); };
   });
 
   afterEach(() => {
@@ -1213,7 +1214,7 @@ describe('websearch command', () => {
     } else {
       delete process.env.BRAVE_API_KEY;
     }
-    process.stdout.write = origStdoutWrite;
+    fs.writeSync = origWriteSync;
   });
 
   test('returns available=false when BRAVE_API_KEY is unset', async () => {

tests/core.test.cjs

@@ -281,6 +281,31 @@ describe('resolveModelInternal', () => {
       assert.strictEqual(resolveModelInternal(tmpDir, 'gsd-planner'), 'opus');
     });
   });
+
+  describe('resolve_model_ids: "omit"', () => {
+    test('returns empty string for known agents', () => {
+      writeConfig({ resolve_model_ids: 'omit' });
+      assert.strictEqual(resolveModelInternal(tmpDir, 'gsd-planner'), '');
+    });
+
+    test('returns empty string for unknown agents', () => {
+      writeConfig({ resolve_model_ids: 'omit' });
+      assert.strictEqual(resolveModelInternal(tmpDir, 'gsd-nonexistent'), '');
+    });
+
+    test('still respects model_overrides even when omit', () => {
+      writeConfig({
+        resolve_model_ids: 'omit',
+        model_overrides: { 'gsd-planner': 'openai/gpt-5.4' },
+      });
+      assert.strictEqual(resolveModelInternal(tmpDir, 'gsd-planner'), 'openai/gpt-5.4');
+    });
+
+    test('returns empty string with inherit profile', () => {
+      writeConfig({ resolve_model_ids: 'omit', model_profile: 'inherit' });
+      assert.strictEqual(resolveModelInternal(tmpDir, 'gsd-planner'), '');
+    });
+  });
 });
 
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