fix(providers): detect router-prefixed reasoning model ids for the new OpenAI contract

src/chrome/src/providers/openai.js

@@ -1,6 +1,7 @@
 import { BaseLLMProvider } from './base.js';
 import { fetchWithFallback } from './fetch-with-fallback.js';
 import {
+  isNewOpenAIContractConfig,
   isOfficialOpenAIConfig,
   shouldUseOpenAIResponsesApi,
   supportsOpenAIAskStreaming,
@@ -160,18 +161,15 @@ export class OpenAICompatibleProvider extends BaseLLMProvider {
   }
 
   /**
-   * Newer OpenAI models (gpt-5, gpt-4.1+, o1, o3, o4) have a different API
-   * contract from the gpt-4o-and-earlier line:
-   *   - reject `max_tokens`, require `max_completion_tokens` instead
-   *   - reject any `temperature` other than the default (1)
-   * Local OpenAI-compatible servers and OpenRouter still use
-   * the legacy contract. Detect by model name + provider type.
+   * Newer OpenAI models (gpt-5 and the o-series) reject `max_tokens` and any
+   * non-default `temperature`, requiring `max_completion_tokens`. Detected by
+   * model id via the shared `isNewOpenAIContractModel` helper (also used by
+   * the settings Compatibility panel so the display and the wire contract
+   * stay in sync). Local OpenAI-compatible servers and LM Studio keep the
+   * legacy contract.
    */
   _isNewOpenAIContract() {
-    const m = (this.config.model || '').toLowerCase();
-    if (this.config.category === 'local') return false;
-    if (this.config.providerName === 'lmstudio') return false;
-    return /^(gpt-5|gpt-4\.1|o1|o3|o4)/.test(m);
+    return isNewOpenAIContractConfig(this.config);
   }
 
   _addMaxTokens(body, options) {

src/chrome/src/providers/provider-compatibility.js

@@ -146,6 +146,36 @@ export function shouldUseOpenAIResponsesApi(config = {}) {
     || /^gpt-5(?:\.(?:2|4|5))?-pro(?:$|-\d{4}-\d{2}-\d{2}$)/.test(model);
 }
 
+/**
+ * Whether a model id uses the newer OpenAI wire contract (max_completion_tokens,
+ * no non-default temperature) — the gpt-5 line and the o-series. gpt-4.1 is
+ * deliberately excluded: it accepts both parameter sets, so it stays on the
+ * legacy contract and keeps explicit temperatures. OpenAI's Responses-only
+ * Pro families also stay legacy when routed through a Chat Completions
+ * provider: those routed endpoints advertise `max_tokens`, while direct
+ * OpenAI calls are selected as Responses before this helper is consulted.
+ * OpenRouter's routed allowlist is intentionally narrow: only GPT-5.6 Terra
+ * variants use max_completion_tokens there; o-series, Pro, batch, and image
+ * routes remain on max_tokens.
+ */
+export function isNewOpenAIContractModel(model) {
+  const m = String(model || '').toLowerCase();
+  if (/(?:^|\/)gpt-5(?:\.(?:2|4|5))?-pro(?:$|[-_.\/:])/.test(m)) return false;
+  return /(?:^|\/)(?:gpt-5|o1|o3|o4)(?:$|[-_.\/])/.test(m);
+}
+
+export function isNewOpenAIContractConfig(config = {}) {
+  const providerName = String(config.providerName || '').trim().toLowerCase();
+  if (config.category === 'local' || providerName === 'lmstudio') return false;
+  if (providerName === 'openrouter') {
+    return /(?:^|\/)gpt-5\.6-terra(?:$|[-_.\/:])/.test(String(config.model || '').toLowerCase());
+  }
+  // Only OpenRouter is covered by the routed-model contract table. Other
+  // compatible endpoints may use slash-prefixed ids with legacy fields.
+  if (String(config.model || '').includes('/') && providerName !== 'openrouter') return false;
+  return isNewOpenAIContractModel(config.model);
+}
+
 export function supportsOpenAIAskStreaming(config = {}) {
   if (!isOfficialOpenAIConfig(config)) return false;
 

src/chrome/src/ui/settings.js

@@ -34,6 +34,7 @@ import {
 } from '../agent/capsolver-config.js';
 import {
   detectedCompatibilityPreset,
+  isNewOpenAIContractConfig,
   normalizeOpenAICompatibleBaseUrl,
   normalizeProviderCompatibility,
   parseProviderExtraBodyJson,
@@ -2304,11 +2305,7 @@ function prettyCompatibilityValue(value) {
 
 function automaticTokenField(config) {
   if (shouldUseOpenAIResponsesApi(config)) return 'max_output_tokens';
-  const model = String(config.model || '').toLowerCase();
-  const isNewOfficialContract = config.type === 'openai'
-    && config.category !== 'local'
-    && config.providerName !== 'lmstudio'
-    && /^(gpt-5|gpt-4\.1|o1|o3|o4)/.test(model);
+  const isNewOfficialContract = config.type === 'openai' && isNewOpenAIContractConfig(config);
   return isNewOfficialContract ? 'max_completion_tokens' : 'max_tokens';
 }
 

src/firefox/src/providers/openai.js

@@ -1,6 +1,7 @@
 import { BaseLLMProvider } from './base.js';
 import { fetchWithTimeout } from './fetch-timeout.js';
 import {
+  isNewOpenAIContractConfig,
   isOfficialOpenAIConfig,
   shouldUseOpenAIResponsesApi,
   supportsOpenAIAskStreaming,
@@ -160,18 +161,15 @@ export class OpenAICompatibleProvider extends BaseLLMProvider {
   }
 
   /**
-   * Newer OpenAI models (gpt-5, gpt-4.1+, o1, o3, o4) have a different API
-   * contract from the gpt-4o-and-earlier line:
-   *   - reject `max_tokens`, require `max_completion_tokens` instead
-   *   - reject any `temperature` other than the default (1)
-   * Local OpenAI-compatible servers and OpenRouter still use
-   * the legacy contract. Detect by model name + provider type.
+   * Newer OpenAI models (gpt-5 and the o-series) reject `max_tokens` and any
+   * non-default `temperature`, requiring `max_completion_tokens`. Detected by
+   * model id via the shared `isNewOpenAIContractModel` helper (also used by
+   * the settings Compatibility panel so the display and the wire contract
+   * stay in sync). Local OpenAI-compatible servers and LM Studio keep the
+   * legacy contract.
    */
   _isNewOpenAIContract() {
-    const m = (this.config.model || '').toLowerCase();
-    if (this.config.category === 'local') return false;
-    if (this.config.providerName === 'lmstudio') return false;
-    return /^(gpt-5|gpt-4\.1|o1|o3|o4)/.test(m);
+    return isNewOpenAIContractConfig(this.config);
   }
 
   _addMaxTokens(body, options) {

src/firefox/src/providers/provider-compatibility.js

@@ -146,6 +146,36 @@ export function shouldUseOpenAIResponsesApi(config = {}) {
     || /^gpt-5(?:\.(?:2|4|5))?-pro(?:$|-\d{4}-\d{2}-\d{2}$)/.test(model);
 }
 
+/**
+ * Whether a model id uses the newer OpenAI wire contract (max_completion_tokens,
+ * no non-default temperature) — the gpt-5 line and the o-series. gpt-4.1 is
+ * deliberately excluded: it accepts both parameter sets, so it stays on the
+ * legacy contract and keeps explicit temperatures. OpenAI's Responses-only
+ * Pro families also stay legacy when routed through a Chat Completions
+ * provider: those routed endpoints advertise `max_tokens`, while direct
+ * OpenAI calls are selected as Responses before this helper is consulted.
+ * OpenRouter's routed allowlist is intentionally narrow: only GPT-5.6 Terra
+ * variants use max_completion_tokens there; o-series, Pro, batch, and image
+ * routes remain on max_tokens.
+ */
+export function isNewOpenAIContractModel(model) {
+  const m = String(model || '').toLowerCase();
+  if (/(?:^|\/)gpt-5(?:\.(?:2|4|5))?-pro(?:$|[-_.\/:])/.test(m)) return false;
+  return /(?:^|\/)(?:gpt-5|o1|o3|o4)(?:$|[-_.\/])/.test(m);
+}
+
+export function isNewOpenAIContractConfig(config = {}) {
+  const providerName = String(config.providerName || '').trim().toLowerCase();
+  if (config.category === 'local' || providerName === 'lmstudio') return false;
+  if (providerName === 'openrouter') {
+    return /(?:^|\/)gpt-5\.6-terra(?:$|[-_.\/:])/.test(String(config.model || '').toLowerCase());
+  }
+  // Only OpenRouter is covered by the routed-model contract table. Other
+  // compatible endpoints may use slash-prefixed ids with legacy fields.
+  if (String(config.model || '').includes('/') && providerName !== 'openrouter') return false;
+  return isNewOpenAIContractModel(config.model);
+}
+
 export function supportsOpenAIAskStreaming(config = {}) {
   if (!isOfficialOpenAIConfig(config)) return false;
 

src/firefox/src/ui/settings.js

@@ -34,6 +34,7 @@ import {
 } from '../agent/capsolver-config.js';
 import {
   detectedCompatibilityPreset,
+  isNewOpenAIContractConfig,
   normalizeOpenAICompatibleBaseUrl,
   normalizeProviderCompatibility,
   parseProviderExtraBodyJson,
@@ -1931,11 +1932,7 @@ function prettyCompatibilityValue(value) {
 
 function automaticTokenField(config) {
   if (shouldUseOpenAIResponsesApi(config)) return 'max_output_tokens';
-  const model = String(config.model || '').toLowerCase();
-  const isNewOfficialContract = config.type === 'openai'
-    && config.category !== 'local'
-    && config.providerName !== 'lmstudio'
-    && /^(gpt-5|gpt-4\.1|o1|o3|o4)/.test(model);
+  const isNewOfficialContract = config.type === 'openai' && isNewOpenAIContractConfig(config);
   return isNewOfficialContract ? 'max_completion_tokens' : 'max_tokens';
 }
 

test/run.js

@@ -48496,7 +48496,12 @@ test('GPT-5.6 Responses request preserves reasoning and converts messages and to
       baseUrl: 'https://openrouter.ai/api/v1',
       model: 'openai/gpt-5.6-terra',
     })._addMaxTokens(compatibleProviderBody, { maxTokens: 5 });
-    assert.equal(compatibleProviderBody.max_tokens, 5, 'compatible providers should keep their requested token cap');
+    assert.equal(
+      compatibleProviderBody.max_completion_tokens,
+      5,
+      'routed gpt-5.6-terra rejects max_tokens, so compatible providers must keep the new-contract token cap',
+    );
+    assert.equal(compatibleProviderBody.max_tokens, undefined, 'routed gpt-5.6-terra must not receive max_tokens');
   }
 });
 
@@ -50193,6 +50198,138 @@ test('OpenAI-compatible local providers always use legacy request token fields',
   }
 });
 
+test('router-prefixed OpenAI reasoning ids use the advertised Chat Completions contract', () => {
+  const messages = [{ role: 'user', content: 'hello' }];
+  const newContractModels = ['openai/gpt-5.6-terra', 'openai/gpt-5.6-terra:batch', 'openai/gpt-5.6-terra:image'];
+  const legacyContractModels = [
+    'openai/o1',
+    'openai/o3-mini',
+    'openai/o4-mini:image',
+    'openai/gpt-5-pro',
+    'openai/gpt-5.2-pro',
+    'openai/gpt-5.4-pro',
+    'openai/gpt-5.5-pro',
+    'openai/gpt-5.5-pro:batch',
+    'openai/gpt-4o',
+    'openai/gpt-4.1',
+    'gpt-4.1',
+    'openrouter/deepseek-v3',
+    'openrouter/mistral-large',
+    'o365-assistant',
+  ];
+  for (const compatibility of [ProviderCompatibilityCh, ProviderCompatibilityFx]) {
+    for (const model of newContractModels) {
+      assert.equal(compatibility.isNewOpenAIContractConfig({ providerName: 'openrouter', model }), true, `${model} should use the new contract`);
+    }
+    for (const model of legacyContractModels) {
+      assert.equal(compatibility.isNewOpenAIContractConfig({ providerName: 'openrouter', model }), false, `${model} should keep the legacy contract`);
+    }
+  }
+
+  for (const Provider of [OpenAIProviderCh, OpenAIProviderFx]) {
+    for (const model of newContractModels) {
+      const provider = new Provider({
+        providerName: 'openrouter',
+        baseUrl: 'https://openrouter.ai/api/v1',
+        model,
+      });
+      assert.equal(provider._isNewOpenAIContract(), true, `${model} should use the new contract`);
+      const body = provider._buildChatCompletionsBody(messages, { maxTokens: 123, temperature: 0.2 }, false);
+      assert.equal(body.max_completion_tokens, 123, `${model} should use max_completion_tokens`);
+      assert.equal(body.max_tokens, undefined, `${model} must not send max_tokens`);
+      assert.equal(body.temperature, undefined, `${model} must omit temperature`);
+    }
+
+    for (const model of legacyContractModels) {
+      const provider = new Provider({
+        providerName: 'openrouter',
+        baseUrl: 'https://openrouter.ai/api/v1',
+        model,
+      });
+      assert.equal(provider._isNewOpenAIContract(), false, `${model} should keep the legacy contract`);
+      const body = provider._buildChatCompletionsBody(messages, { maxTokens: 123 }, false);
+      assert.equal(body.max_tokens, 123, `${model} should use max_tokens`);
+      assert.equal(body.max_completion_tokens, undefined, `${model} must not send max_completion_tokens`);
+      assert.equal(body.temperature, 0.7, `${model} should keep the default temperature`);
+    }
+
+    // gpt-4.1 accepts both parameter sets; it must stay legacy so explicit
+    // temperatures (deterministic planner/compaction paths) are not dropped.
+    const gpt41 = new Provider({
+      providerName: 'openai',
+      baseUrl: 'https://api.openai.com/v1',
+      model: 'gpt-4.1',
+    });
+    assert.equal(gpt41._isNewOpenAIContract(), false, 'gpt-4.1 must keep the legacy contract');
+    const gpt41Body = gpt41._buildChatCompletionsBody(messages, { maxTokens: 123, temperature: 0 }, false);
+    assert.equal(gpt41Body.max_tokens, 123, 'gpt-4.1 should use max_tokens');
+    assert.equal(gpt41Body.temperature, 0, 'gpt-4.1 must preserve an explicit temperature');
+
+    const lmstudio = new Provider({
+      providerName: 'lmstudio',
+      category: 'local',
+      baseUrl: 'http://localhost:1234/v1',
+      model: 'openai/o1',
+    });
+    assert.equal(lmstudio._isNewOpenAIContract(), false, 'lmstudio must keep the legacy contract even for reasoning ids');
+    const lmstudioBody = lmstudio._buildChatCompletionsBody(messages, { maxTokens: 123 }, false);
+    assert.equal(lmstudioBody.max_tokens, 123, 'lmstudio should use max_tokens');
+    assert.equal(lmstudioBody.temperature, 0.7, 'lmstudio should keep the default temperature');
+
+    // The guard must be case-insensitive: a hand-built or duplicated config
+    // with providerName 'LMStudio' still gets the legacy contract.
+    const lmstudioMixedCase = new Provider({
+      providerName: 'LMStudio',
+      category: 'cloud',
+      baseUrl: 'http://localhost:1234/v1',
+      model: 'openai/o1',
+    });
+    assert.equal(lmstudioMixedCase._isNewOpenAIContract(), false, 'LM Studio guard must be case-insensitive');
+
+    const official = new Provider({
+      providerName: 'openai',
+      baseUrl: 'https://api.openai.com/v1',
+      model: 'gpt-5.6-terra',
+    });
+    assert.equal(official._isNewOpenAIContract(), true, 'unprefixed gpt-5.6-terra should still use the new contract');
+    const officialBody = official._buildChatCompletionsBody(messages, { maxTokens: 123 }, false);
+    assert.equal(officialBody.max_completion_tokens, 123, 'gpt-5.6-terra should use max_completion_tokens');
+    assert.equal(officialBody.temperature, undefined, 'gpt-5.6-terra must omit temperature');
+  }
+});
+
+test('OpenAI contract config keeps non-OpenRouter slash ids on legacy fields', () => {
+  for (const [label, compatibility, settingsRel] of [
+    ['chrome', ProviderCompatibilityCh, 'src/chrome/src/ui/settings.js'],
+    ['firefox', ProviderCompatibilityFx, 'src/firefox/src/ui/settings.js'],
+  ]) {
+    assert.equal(
+      compatibility.isNewOpenAIContractConfig({ providerName: 'openrouter', model: 'openai/gpt-5.6-terra' }),
+      true,
+      `${label}: OpenRouter GPT-5.6 Terra should use the new contract`,
+    );
+    for (const model of ['openai/o1', 'openai/o3-mini', 'openai/gpt-5.5-pro', 'openai/gpt-5.2-pro']) {
+      assert.equal(
+        compatibility.isNewOpenAIContractConfig({ providerName: 'openrouter', model }),
+        false,
+        `${label}: ${model} should keep OpenRouter's legacy contract`,
+      );
+    }
+    assert.equal(
+      compatibility.isNewOpenAIContractConfig({ providerName: 'custom-proxy', model: 'vendor/o3-mini' }),
+      false,
+      `${label}: unrelated slash-prefixed providers must keep legacy fields`,
+    );
+    assert.equal(
+      compatibility.isNewOpenAIContractConfig({ providerName: 'lmstudio', category: 'local', model: 'openai/o3' }),
+      false,
+      `${label}: local providers must keep legacy fields`,
+    );
+    const settings = fs.readFileSync(path.join(ROOT, settingsRel), 'utf8');
+    assert.match(settings, /function automaticTokenField\(config\)[\s\S]*isNewOpenAIContractConfig\(config\)/, `${label}: Settings must use the shared config predicate`);
+  }
+});
+
 test('provider compatibility defaults preserve legacy chat request bodies', () => {
   const messages = [{ role: 'system', content: 'rules' }, { role: 'user', content: 'hello' }];
   for (const Provider of [OpenAIProviderCh, OpenAIProviderFx]) {