feat: support Codex fast service-tier aliases

* feat: support Codex fast service-tier aliases

* fix: send Codex fast tier as priority

docs/project-roadmap.md

@@ -41,6 +41,7 @@ All major modularization work is complete. The codebase evolved from monolithic
 
 ### Recent Fixes
 
+- **2026-05-07**: **#760** Codex GPT fast mode is now a first-class CLIProxy model tuning suffix. CCS accepts `gpt-5.4-fast`, `gpt-5.4-high-fast`, and equivalent canonicalized forms in raw env configs, CLI variant creation, and the dashboard model picker; runtime requests now send the base upstream model with `reasoning.effort` plus `service_tier: "priority"` instead of leaking the suffixed alias to CLIProxy upstream routing.
 - **2026-05-07**: **#1103** GitHub Copilot is now treated as a deprecated compatibility bridge. The dashboard moves Copilot out of the active Identity & Access section and into Deprecated, quick setup no longer offers `ghcp` for new onboarding, CLI/help/config copy marks Copilot as deprecated, and existing `ccs copilot` / `ghcp` compatibility paths remain available for current setups.
 - **2026-05-07**: **#1189** Headless settings-profile delegation now preserves native Claude passthrough args without a Claude flag allowlist. Explicit `--channels` values reach Claude Code, future native flags can carry multiple adjacent values, malformed CCS-owned flags no longer swallow the next native flag, and `--prompt=<text>` routes through headless delegation consistently with `--prompt <text>`.
 - **2026-05-03**: **#1172** Local CLIProxy config generation now keeps the CPAMC management dashboard aligned with backend selection. `backend: original` points to the upstream dashboard, `backend: plus` points to the CCS-maintained CPAMC fork, `cliproxy.management_panel_repository` lets advanced users override the panel repository, and stale generated configs are regenerated when the expected panel source changes.

src/cliproxy/ai-providers/__tests__/codex-plan-compatibility.test.ts

@@ -16,6 +16,8 @@ describe('codex plan compatibility', () => {
   it('maps paid-only free-plan models to safe fallbacks', () => {
     expect(getFreePlanFallbackCodexModel('gpt-5.5')).toBe('gpt-5.4');
     expect(getFreePlanFallbackCodexModel('gpt-5.5-xhigh')).toBe('gpt-5.4');
+    expect(getFreePlanFallbackCodexModel('gpt-5.5-high-fast')).toBe('gpt-5.4');
+    expect(getFreePlanFallbackCodexModel('gpt-5.5-fast-high')).toBe('gpt-5.4');
     expect(getFreePlanFallbackCodexModel('gpt-5.3-codex')).toBe('gpt-5.4');
     expect(getFreePlanFallbackCodexModel('gpt-5.3-codex-xhigh')).toBe('gpt-5.4');
     expect(getFreePlanFallbackCodexModel('gpt-5.3-codex(high)')).toBe('gpt-5.4');

src/cliproxy/ai-providers/__tests__/codex-reasoning-proxy-extended-context.test.ts

@@ -147,6 +147,60 @@ describe('CodexReasoningProxy extended-context compatibility', () => {
     expect((capturedBody?.reasoning as JsonRecord | undefined)?.effort).toBe('high');
   });
 
+  it('translates codex fast model suffixes into service_tier', async () => {
+    const capturedBodies: JsonRecord[] = [];
+
+    const upstream = http.createServer((req, res) => {
+      let rawBody = '';
+      req.setEncoding('utf8');
+      req.on('data', (chunk) => {
+        rawBody += chunk;
+      });
+      req.on('end', () => {
+        capturedBodies.push(rawBody ? (JSON.parse(rawBody) as JsonRecord) : {});
+        res.writeHead(200, { 'Content-Type': 'application/json' });
+        res.end(JSON.stringify({ ok: true }));
+      });
+    });
+    cleanupServers.push(upstream);
+
+    const upstreamPort = await listenOnRandomPort(upstream);
+    const proxy = new CodexReasoningProxy({
+      upstreamBaseUrl: `http://127.0.0.1:${upstreamPort}`,
+      modelMap: {
+        defaultModel: 'gpt-5.4',
+      },
+      defaultEffort: 'medium',
+    });
+
+    const proxyPort = await proxy.start();
+    const highFastResponse = await postJson(
+      `http://127.0.0.1:${proxyPort}/api/provider/codex/v1/messages`,
+      {
+        model: 'gpt-5.4-high-fast',
+        messages: [],
+      }
+    );
+    const fastHighResponse = await postJson(
+      `http://127.0.0.1:${proxyPort}/api/provider/codex/v1/messages`,
+      {
+        model: 'gpt-5.4-fast-high',
+        messages: [],
+      }
+    );
+
+    proxy.stop();
+
+    expect(highFastResponse.statusCode).toBe(200);
+    expect(fastHighResponse.statusCode).toBe(200);
+    expect(capturedBodies[0]?.model).toBe('gpt-5.4');
+    expect((capturedBodies[0]?.reasoning as JsonRecord | undefined)?.effort).toBe('high');
+    expect(capturedBodies[0]?.service_tier).toBe('priority');
+    expect(capturedBodies[1]?.model).toBe('gpt-5.4');
+    expect((capturedBodies[1]?.reasoning as JsonRecord | undefined)?.effort).toBe('high');
+    expect(capturedBodies[1]?.service_tier).toBe('priority');
+  });
+
   it('skips reasoning injection when disableEffort is enabled', async () => {
     let capturedBody: JsonRecord | null = null;
 
@@ -189,6 +243,49 @@ describe('CodexReasoningProxy extended-context compatibility', () => {
     expect((capturedBody?.reasoning as JsonRecord | undefined)?.effort).toBeUndefined();
   });
 
+  it('keeps fast service tier when disableEffort is enabled', async () => {
+    let capturedBody: JsonRecord | null = null;
+
+    const upstream = http.createServer((req, res) => {
+      let rawBody = '';
+      req.setEncoding('utf8');
+      req.on('data', (chunk) => {
+        rawBody += chunk;
+      });
+      req.on('end', () => {
+        capturedBody = rawBody ? (JSON.parse(rawBody) as JsonRecord) : {};
+        res.writeHead(200, { 'Content-Type': 'application/json' });
+        res.end(JSON.stringify({ ok: true }));
+      });
+    });
+    cleanupServers.push(upstream);
+
+    const upstreamPort = await listenOnRandomPort(upstream);
+    const proxy = new CodexReasoningProxy({
+      upstreamBaseUrl: `http://127.0.0.1:${upstreamPort}`,
+      modelMap: {
+        defaultModel: 'gpt-5.4',
+      },
+      disableEffort: true,
+    });
+
+    const proxyPort = await proxy.start();
+    const response = await postJson(
+      `http://127.0.0.1:${proxyPort}/api/provider/codex/v1/messages`,
+      {
+        model: 'gpt-5.4-high-fast',
+        messages: [],
+      }
+    );
+
+    proxy.stop();
+
+    expect(response.statusCode).toBe(200);
+    expect(capturedBody?.model).toBe('gpt-5.4');
+    expect((capturedBody?.reasoning as JsonRecord | undefined)?.effort).toBeUndefined();
+    expect(capturedBody?.service_tier).toBe('priority');
+  });
+
   it('does not strip unknown model ids that merely end with "-high"', async () => {
     let capturedBody: JsonRecord | null = null;
 

src/cliproxy/ai-providers/__tests__/model-id-normalizer.test.ts

@@ -123,10 +123,17 @@ describe('model-id-normalizer', () => {
       expect(normalizeCodexLegacyModelAliases('gpt-5-codex')).toBe('gpt-5.4');
       expect(normalizeCodexLegacyModelAliases('gpt-5-codex-mini[1m]')).toBe('gpt-5.4-mini[1m]');
       expect(normalizeCodexLegacyModelAliases('gpt-5-codex-high')).toBe('gpt-5.4-high');
+      expect(normalizeCodexLegacyModelAliases('gpt-5-codex-fast-high')).toBe('gpt-5.4-high-fast');
       expect(normalizeCodexLegacyModelAliases('gpt-5-codex-high[1m]')).toBe('gpt-5.4-high[1m]');
+      expect(normalizeCodexLegacyModelAliases('gpt-5-codex-high-fast[1m]')).toBe(
+        'gpt-5.4-high-fast[1m]'
+      );
       expect(normalizeModelIdForProvider('gpt-5.2-codex', 'codex')).toBe('gpt-5.2');
       expect(normalizeModelIdForProvider('gpt-5.1-codex-mini', 'codex')).toBe('gpt-5.4-mini');
       expect(canonicalizeModelIdForProvider('gpt-5-codex-high', 'codex')).toBe('gpt-5.4-high');
+      expect(canonicalizeModelIdForProvider('gpt-5-codex-fast-high', 'codex')).toBe(
+        'gpt-5.4-high-fast'
+      );
     });
   });
 

src/cliproxy/ai-providers/codex-plan-compatibility.ts

@@ -10,7 +10,8 @@ export type CodexPlanType = CodexQuotaResult['planType'];
 
 const FREE_SAFE_DEFAULT_MODEL = 'gpt-5.4';
 const FREE_SAFE_FAST_MODEL = 'gpt-5.4-mini';
-const CODEX_EFFORT_SUFFIX_REGEX = /-(xhigh|high|medium)$/i;
+const CODEX_TUNING_SUFFIX_REGEX =
+  /(?:-(?:xhigh|high|medium)(?:-fast)?|-fast(?:-(?:xhigh|high|medium))?)$/i;
 const CODEX_PAREN_SUFFIX_REGEX = /\((xhigh|high|medium)\)$/i;
 const EXTENDED_CONTEXT_SUFFIX_REGEX = /\[1m\]$/i;
 const KNOWN_CODEX_MODELS = new Set(
@@ -57,7 +58,7 @@ export function normalizeCodexModelId(model: string): string {
     .trim()
     .replace(EXTENDED_CONTEXT_SUFFIX_REGEX, '')
     .replace(CODEX_PAREN_SUFFIX_REGEX, '')
-    .replace(CODEX_EFFORT_SUFFIX_REGEX, '')
+    .replace(CODEX_TUNING_SUFFIX_REGEX, '')
     .trim();
   return normalizeModelIdForProvider(stripped, 'codex').trim().toLowerCase();
 }

src/cliproxy/ai-providers/codex-reasoning-proxy.ts

@@ -9,6 +9,8 @@ import {
 import { getModelMaxLevel } from '../model-catalog';
 
 export type CodexReasoningEffort = 'medium' | 'high' | 'xhigh';
+export type CodexServiceTier = 'fast';
+type CodexServiceTierRequestValue = 'priority';
 
 export interface CodexReasoningModelMap {
   opusModel?: string;
@@ -41,10 +43,15 @@ interface ForwardJsonContext {
   requestedModel: string | null;
   attemptedUpstreamModel: string | null;
   effort: CodexReasoningEffort | null;
+  serviceTier: CodexServiceTier | null;
   retryCount: number;
 }
 
 const EXTENDED_CONTEXT_SUFFIX_REGEX = /\[1m\]$/i;
+const CODEX_TUNING_SUFFIX_TOKEN_REGEX = /-(xhigh|high|medium|fast)$/i;
+const CODEX_SERVICE_TIER_REQUEST_VALUE: Record<CodexServiceTier, CodexServiceTierRequestValue> = {
+  fast: 'priority',
+};
 
 function stripExtendedContextSuffix(model: string): string {
   return model.replace(EXTENDED_CONTEXT_SUFFIX_REGEX, '').trim();
@@ -58,16 +65,35 @@ function isRecord(value: unknown): value is Record<string, unknown> {
   return typeof value === 'object' && value !== null && !Array.isArray(value);
 }
 
-function parseModelEffortSuffix(
-  model: string
-): { upstreamModel: string; effort: CodexReasoningEffort } | null {
+function parseModelTuningSuffix(model: string): {
+  upstreamModel: string;
+  effort: CodexReasoningEffort | null;
+  serviceTier: CodexServiceTier | null;
+} | null {
   const normalizedModel = stripExtendedContextSuffix(model);
-  const match = normalizedModel.match(/^(.*)-(xhigh|high|medium)$/i);
-  if (!match) return null;
-  const upstreamModel = match[1]?.trim();
-  const effort = match[2]?.toLowerCase() as CodexReasoningEffort;
+  let upstreamModel = normalizedModel;
+  let effort: CodexReasoningEffort | null = null;
+  let serviceTier: CodexServiceTier | null = null;
+
+  for (let consumed = 0; consumed < 2; consumed += 1) {
+    const match = upstreamModel.match(CODEX_TUNING_SUFFIX_TOKEN_REGEX);
+    if (!match?.[1]) break;
+
+    const token = match[1].toLowerCase();
+    if (token === 'fast') {
+      if (serviceTier) break;
+      serviceTier = 'fast';
+    } else {
+      if (effort) break;
+      effort = token as CodexReasoningEffort;
+    }
+
+    upstreamModel = upstreamModel.slice(0, -match[0].length).trim();
+  }
+
+  if (!effort && !serviceTier) return null;
   if (!upstreamModel) return null;
-  return { upstreamModel, effort };
+  return { upstreamModel, effort, serviceTier };
 }
 
 function isKnownCodexModelId(
@@ -154,19 +180,36 @@ export function getEffortForModel(
 export function injectReasoningEffortIntoBody(
   body: unknown,
   effort: CodexReasoningEffort
+): unknown {
+  return injectCodexRequestTuningIntoBody(body, { effort, serviceTier: null });
+}
+
+export function injectCodexRequestTuningIntoBody(
+  body: unknown,
+  tuning: {
+    effort: CodexReasoningEffort | null;
+    serviceTier: CodexServiceTier | null;
+  }
 ): unknown {
   if (!isRecord(body)) return body;
 
   // OpenAI Responses API knob: reasoning: { effort: "..." }
   // Always override effort (user expectation).
   const existingReasoning = isRecord(body.reasoning) ? body.reasoning : {};
-  return {
-    ...body,
-    reasoning: {
+  const tunedBody = { ...body };
+
+  if (tuning.effort) {
+    tunedBody.reasoning = {
       ...existingReasoning,
-      effort,
-    },
-  };
+      effort: tuning.effort,
+    };
+  }
+
+  if (tuning.serviceTier) {
+    tunedBody.service_tier = CODEX_SERVICE_TIER_REQUEST_VALUE[tuning.serviceTier];
+  }
+
+  return tunedBody;
 }
 
 export class CodexReasoningProxy {
@@ -191,7 +234,8 @@ export class CodexReasoningProxy {
     at: string;
     model: string | null;
     upstreamModel: string | null;
-    effort: CodexReasoningEffort;
+    effort: CodexReasoningEffort | null;
+    serviceTier: CodexServiceTier | null;
     path: string;
   }> = [];
   private readonly counts: Record<CodexReasoningEffort, number> = { medium: 0, high: 0, xhigh: 0 };
@@ -226,14 +270,21 @@ export class CodexReasoningProxy {
   private buildForwardBody(
     body: unknown,
     upstreamModel: string | null,
-    effort: CodexReasoningEffort | null
+    tuning: {
+      effort: CodexReasoningEffort | null;
+      serviceTier: CodexServiceTier | null;
+    }
   ): unknown {
     const withUpstreamModel =
       upstreamModel && isRecord(body) ? { ...body, model: upstreamModel } : body;
-    if (this.config.disableEffort || !effort) {
+    const effort = this.config.disableEffort ? null : tuning.effort;
+    if (!effort && !tuning.serviceTier) {
       return withUpstreamModel;
     }
-    return injectReasoningEffortIntoBody(withUpstreamModel, effort);
+    return injectCodexRequestTuningIntoBody(withUpstreamModel, {
+      effort,
+      serviceTier: tuning.serviceTier,
+    });
   }
 
   private sendBufferedResponse(
@@ -247,14 +298,17 @@ export class CodexReasoningProxy {
   }
 
   /**
-   * Treat trailing "-high/-medium/-xhigh" as an effort alias only for known codex models.
+   * Treat trailing "-high/-medium/-xhigh" and "-fast" as Codex tuning aliases
+   * only for known codex models.
    * Prevents stripping legitimate upstream model IDs that happen to end with those tokens.
    */
-  private parseEffortAlias(
-    model: string | null
-  ): { upstreamModel: string; effort: CodexReasoningEffort } | null {
+  private parseTuningAlias(model: string | null): {
+    upstreamModel: string;
+    effort: CodexReasoningEffort | null;
+    serviceTier: CodexServiceTier | null;
+  } | null {
     if (!model) return null;
-    const parsed = parseModelEffortSuffix(model);
+    const parsed = parseModelTuningSuffix(model);
     if (!parsed) return null;
     if (!isKnownCodexModelId(parsed.upstreamModel, this.modelEffort)) {
       return null;
@@ -296,11 +350,21 @@ export class CodexReasoningProxy {
   private record(
     model: string | null,
     upstreamModel: string | null,
-    effort: CodexReasoningEffort,
+    effort: CodexReasoningEffort | null,
+    serviceTier: CodexServiceTier | null,
     path: string
   ): void {
-    this.counts[effort] += 1;
-    this.recent.push({ at: new Date().toISOString(), model, upstreamModel, effort, path });
+    if (effort) {
+      this.counts[effort] += 1;
+    }
+    this.recent.push({
+      at: new Date().toISOString(),
+      model,
+      upstreamModel,
+      effort,
+      serviceTier,
+      path,
+    });
     if (this.recent.length > 50) this.recent.shift();
   }
 
@@ -418,12 +482,13 @@ export class CodexReasoningProxy {
         ? stripExtendedContextSuffix(originalModel)
         : null;
 
-      // Support "model aliases" like `gpt-5.2-codex-xhigh` by translating to:
-      // - upstream model: `gpt-5.2-codex`
-      // - reasoning.effort: `xhigh`
+      // Support "model aliases" like `gpt-5.4-high-fast` by translating to:
+      // - upstream model: `gpt-5.4`
+      // - reasoning.effort: `high`
+      // - service_tier: `priority` (Codex request value for fast mode)
       //
-      // This allows tier→effort mapping without inventing upstream model IDs.
-      const suffixParsed = this.parseEffortAlias(normalizedRequestModel);
+      // This allows tier/speed mapping without inventing upstream model IDs.
+      const suffixParsed = this.parseTuningAlias(normalizedRequestModel);
       const requestedUpstreamModel = suffixParsed?.upstreamModel ?? normalizedRequestModel;
       const rememberedFallback = this.getRememberedFallback(requestedUpstreamModel);
       const upstreamModel = rememberedFallback ?? requestedUpstreamModel;
@@ -436,14 +501,15 @@ export class CodexReasoningProxy {
           : !this.config.disableEffort
             ? requestedEffort
             : null;
-      const rewritten = this.buildForwardBody(parsed, upstreamModel, effort);
+      const serviceTier = suffixParsed?.serviceTier ?? null;
+      const rewritten = this.buildForwardBody(parsed, upstreamModel, { effort, serviceTier });
 
-      if (effort) {
-        this.record(originalModel, upstreamModel, effort, requestPath);
+      if (effort || serviceTier) {
+        this.record(originalModel, upstreamModel, effort, serviceTier, requestPath);
         this.trace(
           `[${new Date().toISOString()}] model=${originalModel ?? 'null'} upstreamModel=${
             upstreamModel ?? 'null'
-          } effort=${effort} path=${requestPath}`
+          } effort=${effort ?? 'null'} serviceTier=${serviceTier ?? 'null'} path=${requestPath}`
         );
       } else {
         this.log(`[disabled] model=${originalModel ?? 'null'} -> passthrough (no reasoning)`);
@@ -458,6 +524,7 @@ export class CodexReasoningProxy {
         requestedModel: requestedUpstreamModel,
         attemptedUpstreamModel: upstreamModel,
         effort,
+        serviceTier,
         retryCount: 0,
       });
     } catch (error) {
@@ -630,7 +697,10 @@ export class CodexReasoningProxy {
                   !this.config.disableEffort && context.effort
                     ? capEffortAtModelMax(fallbackModel, context.effort)
                     : null;
-                const retryBody = this.buildForwardBody(body, fallbackModel, retryEffort);
+                const retryBody = this.buildForwardBody(body, fallbackModel, {
+                  effort: retryEffort,
+                  serviceTier: context.serviceTier,
+                });
 
                 this.log(
                   `Upstream rejected model "${context.attemptedUpstreamModel}". Retrying ${context.requestPath} with "${fallbackModel}".`

src/cliproxy/ai-providers/model-id-normalizer.ts

@@ -26,7 +26,7 @@ const DENIED_ANTIGRAVITY_OPUS_45_REGEX =
 const DENIED_ANTIGRAVITY_SONNET_45_REGEX =
   /claude-sonnet-4(?:[.-])5(?:-thinking)?(?=(?:$|[^a-z0-9]))/gi;
 const CANONICAL_ANTIGRAVITY_OPUS_46_MODEL = 'claude-opus-4-6-thinking';
-const CODEX_EFFORT_SUFFIX_REGEX = /-(xhigh|high|medium)$/i;
+const CODEX_TUNING_SUFFIX_TOKEN_REGEX = /-(xhigh|high|medium|fast)$/i;
 const CODEX_LEGACY_MODEL_ALIASES: Readonly<Record<string, string>> = Object.freeze({
   'gpt-5-codex': 'gpt-5.4',
   'gpt-5-codex-mini': 'gpt-5.4-mini',
@@ -65,15 +65,31 @@ function splitBaseModelAndSuffix(model: string): { baseModel: string; suffix: st
   };
 }
 
-function splitCodexEffortSuffix(model: string): { baseModel: string; suffix: string } {
-  const match = model.match(CODEX_EFFORT_SUFFIX_REGEX);
-  if (!match?.[0]) {
-    return { baseModel: model, suffix: '' };
+function splitCodexTuningSuffix(model: string): { baseModel: string; suffix: string } {
+  let baseModel = model;
+  let effort: string | null = null;
+  let serviceTier: 'fast' | null = null;
+
+  for (let consumed = 0; consumed < 2; consumed += 1) {
+    const match = baseModel.match(CODEX_TUNING_SUFFIX_TOKEN_REGEX);
+    if (!match?.[1]) break;
+
+    const token = match[1].toLowerCase();
+    if (token === 'fast') {
+      if (serviceTier) break;
+      serviceTier = 'fast';
+    } else {
+      if (effort) break;
+      effort = token;
+    }
+
+    baseModel = baseModel.slice(0, -match[0].length);
   }
 
+  const suffix = [effort, serviceTier].filter(Boolean).join('-');
   return {
-    baseModel: model.slice(0, -match[0].length),
-    suffix: match[0],
+    baseModel,
+    suffix: suffix ? `-${suffix}` : '',
   };
 }
 
@@ -109,11 +125,11 @@ export function isIFlowProvider(provider: ProviderLike): boolean {
   return provider.trim().toLowerCase() === 'iflow';
 }
 
-/** Strip Codex effort suffixes while preserving trailing config suffixes. */
+/** Strip Codex effort/service-tier suffixes while preserving trailing config suffixes. */
 export function stripCodexEffortSuffix(model: string): string {
   const trimmed = trimModelId(model);
   const { baseModel, suffix } = splitBaseModelAndSuffix(trimmed);
-  const { baseModel: withoutEffort } = splitCodexEffortSuffix(baseModel);
+  const { baseModel: withoutEffort } = splitCodexTuningSuffix(baseModel);
   return `${withoutEffort}${suffix}`;
 }
 
@@ -121,12 +137,12 @@ export function stripCodexEffortSuffix(model: string): string {
 export function normalizeCodexLegacyModelAliases(model: string): string {
   const trimmed = trimModelId(model);
   const { baseModel, suffix } = splitBaseModelAndSuffix(trimmed);
-  const { baseModel: baseWithoutEffort, suffix: effortSuffix } = splitCodexEffortSuffix(baseModel);
+  const { baseModel: baseWithoutEffort, suffix: tuningSuffix } = splitCodexTuningSuffix(baseModel);
   const replacement = CODEX_LEGACY_MODEL_ALIASES[baseWithoutEffort.trim().toLowerCase()];
   if (!replacement) {
     return trimmed;
   }
-  return `${replacement}${effortSuffix}${suffix}`;
+  return `${replacement}${tuningSuffix}${suffix}`;
 }
 
 /**

src/cliproxy/config/thinking-config.ts

@@ -16,9 +16,15 @@ import { getThinkingConfig } from '../../config/config-loader-facade';
 /** Model tier types for thinking budget defaults */
 export type ModelTier = 'opus' | 'sonnet' | 'haiku';
 
+const CODEX_EFFORT_REGEX = /^(medium|high|xhigh)$/i;
+const CODEX_FAST_TUNING_VALUE_REGEX =
+  /^(?:(medium|high|xhigh)-fast|fast-(medium|high|xhigh)|fast)$/i;
+const CODEX_TUNING_SUFFIX_REGEX =
+  /(?:-(?:xhigh|high|medium)(?:-fast)?|-fast(?:-(?:xhigh|high|medium))?)$/i;
+
 /**
  * Normalize model ID for provider capability lookup.
- * Codex may carry effort suffixes in either legacy "(high)" or current "-high" forms.
+ * Codex may carry effort/service-tier suffixes in legacy "(high)" or current "-high-fast" forms.
  */
 function normalizeModelForThinkingLookup(model: string, provider: CLIProxyProvider): string {
   const withoutExtendedContext = model.replace(/\[1m\]$/i, '').trim();
@@ -26,8 +32,10 @@ function normalizeModelForThinkingLookup(model: string, provider: CLIProxyProvid
 
   if (provider !== 'codex') return providerNormalized;
 
-  // New codex suffix form: gpt-5.3-codex-high -> gpt-5.3-codex
-  const codexSuffixMatch = providerNormalized.match(/^(.*)-(xhigh|high|medium)$/i);
+  // New codex suffix forms: gpt-5.4-high-fast, gpt-5.4-fast-high -> gpt-5.4
+  const codexSuffixMatch = providerNormalized.match(
+    /^(.*?)(?:-(?:xhigh|high|medium)(?:-fast)?|-fast(?:-(?:xhigh|high|medium))?)$/i
+  );
   if (codexSuffixMatch?.[1]) {
     return codexSuffixMatch[1].trim();
   }
@@ -82,8 +90,6 @@ function applyThinkingSuffixForProvider(
   thinkingValue: string | number,
   provider?: CLIProxyProvider
 ): string {
-  const codexEffortRegex = /^(medium|high|xhigh)$/i;
-  const codexModelSuffixRegex = /-(medium|high|xhigh)$/i;
   const parenthesizedSuffixMatch = model.match(/\(([^)]+)\)$/);
 
   // Existing parenthesized suffix:
@@ -93,7 +99,7 @@ function applyThinkingSuffixForProvider(
   if (parenthesizedSuffixMatch) {
     if (provider === 'codex') {
       const normalizedParensValue = parenthesizedSuffixMatch[1]?.trim().toLowerCase() || '';
-      if (codexEffortRegex.test(normalizedParensValue)) {
+      if (CODEX_EFFORT_REGEX.test(normalizedParensValue)) {
         return model.replace(/\([^)]+\)$/, `-${normalizedParensValue}`);
       }
     }
@@ -110,11 +116,11 @@ function applyThinkingSuffixForProvider(
   }
 
   if (provider === 'codex') {
-    if (codexModelSuffixRegex.test(model)) {
+    if (CODEX_TUNING_SUFFIX_REGEX.test(model)) {
       return model;
     }
     const normalized = String(thinkingValue).trim().toLowerCase();
-    if (codexEffortRegex.test(normalized)) {
+    if (CODEX_EFFORT_REGEX.test(normalized) || CODEX_FAST_TUNING_VALUE_REGEX.test(normalized)) {
       return `${model}-${normalized}`;
     }
   }

src/cliproxy/model-catalog.ts

@@ -66,6 +66,8 @@ export interface ModelEntry {
   extendedContext?: boolean;
   /** Whether model can read image inputs natively without the Image transformer */
   nativeImageInput?: boolean;
+  /** Additional Codex service-tier suffixes supported by this model. */
+  codexServiceTiers?: Array<'fast'>;
 }
 
 /**
@@ -200,6 +202,7 @@ export const MODEL_CATALOG: Partial<Record<CLIProxyProvider, ProviderCatalog>> =
           maxLevel: 'xhigh',
           dynamicAllowed: false,
         },
+        codexServiceTiers: ['fast'],
       },
       {
         id: 'gpt-5.4',
@@ -211,6 +214,7 @@ export const MODEL_CATALOG: Partial<Record<CLIProxyProvider, ProviderCatalog>> =
           maxLevel: 'xhigh',
           dynamicAllowed: false,
         },
+        codexServiceTiers: ['fast'],
       },
       {
         id: 'gpt-5.4-mini',

src/commands/cliproxy/variant-subcommand.ts

@@ -130,6 +130,64 @@ function formatModelOption(model: ModelEntry): string {
   return `${model.name}${tierBadge}`;
 }
 
+const CODEX_EFFORTS_IN_ORDER = ['medium', 'high', 'xhigh'] as const;
+type CodexSelectableEffort = (typeof CODEX_EFFORTS_IN_ORDER)[number];
+
+function getCodexSelectableEfforts(model: ModelEntry): CodexSelectableEffort[] {
+  const maxLevel = model.thinking?.maxLevel;
+  const maxIndex = CODEX_EFFORTS_IN_ORDER.findIndex((effort) => effort === maxLevel);
+  if (maxIndex < 0) return [];
+  return CODEX_EFFORTS_IN_ORDER.slice(0, maxIndex + 1);
+}
+
+function getCodexModelOptionValues(model: ModelEntry, modelId: string): string[] {
+  const serviceTiers = model.codexServiceTiers ?? [];
+  const optionValues: string[] = [modelId];
+
+  for (const serviceTier of serviceTiers) {
+    optionValues.push(`${modelId}-${serviceTier}`);
+  }
+
+  for (const effort of getCodexSelectableEfforts(model)) {
+    const effortModelId = `${modelId}-${effort}`;
+    optionValues.push(effortModelId);
+    for (const serviceTier of serviceTiers) {
+      optionValues.push(`${effortModelId}-${serviceTier}`);
+    }
+  }
+
+  return optionValues;
+}
+
+function getModelOptionsForProvider(
+  provider: CLIProxyProvider,
+  catalog: NonNullable<ReturnType<typeof getProviderCatalog>>,
+  routing: CliproxyProviderRoutingHints | undefined
+): Array<{ id: string; label: string }> {
+  return catalog.models.flatMap((model) => {
+    const modelId = getSelectableModelId(model.id, routing);
+    const optionValues =
+      provider === 'codex' ? getCodexModelOptionValues(model, modelId) : [modelId];
+    return optionValues.map((optionValue) => ({
+      id: optionValue,
+      label:
+        provider === 'codex'
+          ? `${optionValue} (${formatModelOption(model)})`
+          : formatModelOption(model),
+    }));
+  });
+}
+
+function getDefaultModelOptionIndex(
+  modelOptions: Array<{ id: string }>,
+  catalog: NonNullable<ReturnType<typeof getProviderCatalog>>,
+  routing: CliproxyProviderRoutingHints | undefined
+): number {
+  const defaultModelId = getSelectableModelId(catalog.defaultModel, routing);
+  const defaultIdx = modelOptions.findIndex((option) => option.id === defaultModelId);
+  return defaultIdx >= 0 ? defaultIdx : 0;
+}
+
 function getSelectableModelId(
   modelId: string,
   routing: CliproxyProviderRoutingHints | undefined
@@ -207,13 +265,13 @@ async function selectTierConfig(
     const routing = (await getCatalogRoutingSnapshot()).routing[provider as CLIProxyProvider];
     const catalog = getProviderCatalog(provider as CLIProxyProvider);
     if (catalog) {
-      const modelOptions = catalog.models.map((m) => ({
-        id: getSelectableModelId(m.id, routing),
-        label: formatModelOption(m),
-      }));
-      const defaultIdx = catalog.models.findIndex((m) => m.id === catalog.defaultModel);
+      const modelOptions = getModelOptionsForProvider(
+        provider as CLIProxyProvider,
+        catalog,
+        routing
+      );
       model = await InteractivePrompt.selectFromList(`Model for ${tierName}:`, modelOptions, {
-        defaultIndex: defaultIdx >= 0 ? defaultIdx : 0,
+        defaultIndex: getDefaultModelOptionIndex(modelOptions, catalog, routing),
       });
     }
   }
@@ -468,13 +526,13 @@ export async function handleCreate(
       const routing = (await getCatalogRoutingSnapshot()).routing[provider as CLIProxyProvider];
       const catalog = getProviderCatalog(provider as CLIProxyProvider);
       if (catalog) {
-        const modelOptions = catalog.models.map((m) => ({
-          id: getSelectableModelId(m.id, routing),
-          label: formatModelOption(m),
-        }));
-        const defaultIdx = catalog.models.findIndex((m) => m.id === catalog.defaultModel);
+        const modelOptions = getModelOptionsForProvider(
+          provider as CLIProxyProvider,
+          catalog,
+          routing
+        );
         model = await InteractivePrompt.selectFromList('Select model:', modelOptions, {
-          defaultIndex: defaultIdx >= 0 ? defaultIdx : 0,
+          defaultIndex: getDefaultModelOptionIndex(modelOptions, catalog, routing),
         });
       }
     }

ui/src/components/cliproxy/provider-editor/model-config-section.tsx

@@ -229,8 +229,8 @@ export function ModelConfigSection({
         {provider === 'codex' && (
           <p className="text-[11px] text-muted-foreground mb-3 rounded-md border bg-muted/30 px-2.5 py-2">
             Codex tip: suffixes <code>-medium</code>, <code>-high</code>, and <code>-xhigh</code>{' '}
-            pin reasoning effort. Select a suffixed model to pin effort; unsuffixed models use
-            Thinking settings.
+            pin reasoning effort. <code>-fast</code> enables the Codex fast service tier on models
+            that support it, including combined forms such as <code>gpt-5.4-high-fast</code>.
           </p>
         )}
         <div className="space-y-4">

ui/src/components/cliproxy/provider-model-selector.tsx

@@ -12,8 +12,12 @@ import { Badge } from '@/components/ui/badge';
 import { SearchableSelect } from '@/components/ui/searchable-select';
 import { Skeleton } from '@/components/ui/skeleton';
 import type { CliproxyProviderRoutingHints } from '@/lib/api-client';
-import type { CodexEffort } from '@/lib/codex-effort';
-import { getCodexEffortDisplay, getCodexEffortVariants } from '@/lib/codex-effort';
+import type { CodexEffort, CodexServiceTier } from '@/lib/codex-effort';
+import {
+  getCodexEffortDisplay,
+  getCodexEffortVariants,
+  parseCodexServiceTier,
+} from '@/lib/codex-effort';
 import { getResolvedCatalogModels, getSupplementalCatalogModels } from '@/lib/model-catalogs';
 import { cn } from '@/lib/utils';
 
@@ -38,6 +42,8 @@ export interface ModelEntry {
   };
   /** Highest codex reasoning-effort suffix this model supports in the dashboard UI. */
   codexMaxEffort?: CodexEffort;
+  /** Additional Codex service-tier suffixes supported by this model in the dashboard UI. */
+  codexServiceTiers?: CodexServiceTier[];
 }
 
 /** Provider catalog */
@@ -112,6 +118,17 @@ function CodexEffortBadge({ modelId }: { modelId: string | undefined }) {
   );
 }
 
+function CodexServiceTierBadge({ modelId }: { modelId: string | undefined }) {
+  const serviceTier = parseCodexServiceTier(modelId);
+  if (!serviceTier) return null;
+
+  return (
+    <Badge variant="secondary" className="text-[9px] h-4 px-1 uppercase">
+      {serviceTier}
+    </Badge>
+  );
+}
+
 export function ProviderModelSelector({
   catalog,
   isLoading,
@@ -318,10 +335,13 @@ function getPreferredOptionValue(
 
 function getModelOptionValues(
   codexMaxEffort: CodexEffort | undefined,
+  codexServiceTiers: readonly CodexServiceTier[] | undefined,
   optionValue: string,
   isCodexProvider: boolean
 ): string[] {
-  return isCodexProvider ? getCodexEffortVariants(optionValue, codexMaxEffort) : [optionValue];
+  return isCodexProvider
+    ? getCodexEffortVariants(optionValue, codexMaxEffort, codexServiceTiers)
+    : [optionValue];
 }
 
 export function FlexibleModelSelector({
@@ -356,6 +376,7 @@ export function FlexibleModelSelector({
         resolvedCatalogModels.flatMap((model) =>
           getModelOptionValues(
             model.codexMaxEffort,
+            model.codexServiceTiers,
             getPreferredOptionValue(model.id, routingHints.get(model.id.toLowerCase())),
             isCodexProvider
           )
@@ -372,6 +393,7 @@ export function FlexibleModelSelector({
     const routingHint = routingHints.get(model.id.toLowerCase());
     const optionValues = getModelOptionValues(
       model.codexMaxEffort,
+      model.codexServiceTiers,
       getPreferredOptionValue(model.id, routingHint),
       isCodexProvider
     );
@@ -390,6 +412,7 @@ export function FlexibleModelSelector({
             </Badge>
           ) : null}
           {isCodexProvider && <CodexEffortBadge modelId={optionValue} />}
+          {isCodexProvider && <CodexServiceTierBadge modelId={optionValue} />}
         </div>
       ),
       itemContent: (
@@ -407,6 +430,7 @@ export function FlexibleModelSelector({
             </Badge>
           ) : null}
           {isCodexProvider && <CodexEffortBadge modelId={optionValue} />}
+          {isCodexProvider && <CodexServiceTierBadge modelId={optionValue} />}
         </div>
       ),
     }));
@@ -423,6 +447,7 @@ export function FlexibleModelSelector({
     .flatMap((model) => {
       const routingHint = routingHints.get(model.id.toLowerCase());
       const optionValues = getModelOptionValues(
+        undefined,
         undefined,
         getPreferredOptionValue(model.id, routingHint),
         isCodexProvider
@@ -442,6 +467,7 @@ export function FlexibleModelSelector({
               </Badge>
             ) : null}
             {isCodexProvider && <CodexEffortBadge modelId={optionValue} />}
+            {isCodexProvider && <CodexServiceTierBadge modelId={optionValue} />}
           </div>
         ),
         itemContent: (
@@ -458,6 +484,7 @@ export function FlexibleModelSelector({
               </Badge>
             ) : null}
             {isCodexProvider && <CodexEffortBadge modelId={optionValue} />}
+            {isCodexProvider && <CodexServiceTierBadge modelId={optionValue} />}
           </div>
         ),
       }));

ui/src/lib/codex-effort.ts

@@ -1,37 +1,69 @@
 export type CodexEffort = 'medium' | 'high' | 'xhigh';
+export type CodexServiceTier = 'fast';
 
-const CODEX_EFFORT_SUFFIX_REGEX = /-(medium|high|xhigh)$/i;
+const CODEX_TUNING_SUFFIX_TOKEN_REGEX = /-(medium|high|xhigh|fast)$/i;
 const CODEX_EFFORTS_IN_ORDER: readonly CodexEffort[] = ['medium', 'high', 'xhigh'];
 
 function trimModelId(modelId: string | undefined): string {
   return modelId?.trim() ?? '';
 }
 
+function parseCodexTuningSuffix(modelId: string | undefined): {
+  baseModel: string;
+  effort: CodexEffort | undefined;
+  serviceTier: CodexServiceTier | undefined;
+} {
+  let baseModel = trimModelId(modelId);
+  let effort: CodexEffort | undefined;
+  let serviceTier: CodexServiceTier | undefined;
+
+  for (let consumed = 0; consumed < 2; consumed += 1) {
+    const match = baseModel.match(CODEX_TUNING_SUFFIX_TOKEN_REGEX);
+    if (!match?.[1]) break;
+
+    const token = match[1].toLowerCase();
+    if (token === 'fast') {
+      if (serviceTier) break;
+      serviceTier = 'fast';
+    } else {
+      if (effort) break;
+      effort = token as CodexEffort;
+    }
+
+    baseModel = baseModel.slice(0, -match[0].length);
+  }
+
+  return { baseModel, effort, serviceTier };
+}
+
 export function parseCodexEffort(modelId: string | undefined): CodexEffort | undefined {
-  if (!modelId) return undefined;
-  const match = trimModelId(modelId).match(CODEX_EFFORT_SUFFIX_REGEX);
-  if (!match?.[1]) return undefined;
-  return match[1].toLowerCase() as CodexEffort;
+  return parseCodexTuningSuffix(modelId).effort;
+}
+
+export function parseCodexServiceTier(modelId: string | undefined): CodexServiceTier | undefined {
+  return parseCodexTuningSuffix(modelId).serviceTier;
 }
 
 export function stripCodexEffortSuffix(modelId: string | undefined): string {
-  return trimModelId(modelId).replace(CODEX_EFFORT_SUFFIX_REGEX, '');
+  return parseCodexTuningSuffix(modelId).baseModel;
 }
 
 export function applyCodexEffortSuffix(
   modelId: string | undefined,
   effort: CodexEffort | undefined
 ): string {
-  const normalizedModelId = stripCodexEffortSuffix(modelId);
+  const parsed = parseCodexTuningSuffix(modelId);
+  const normalizedModelId = parsed.baseModel;
   if (!normalizedModelId || !effort) {
-    return normalizedModelId;
+    return parsed.serviceTier ? `${normalizedModelId}-${parsed.serviceTier}` : normalizedModelId;
   }
-  return `${normalizedModelId}-${effort}`;
+  return [normalizedModelId, effort, parsed.serviceTier].filter(Boolean).join('-');
 }
 
 export function getCodexEffortVariants(
   modelId: string,
-  maxEffort: CodexEffort | undefined
+  maxEffort: CodexEffort | undefined,
+  serviceTiers: readonly CodexServiceTier[] = []
 ): string[] {
   if (!maxEffort) {
     const explicitEffort = parseCodexEffort(modelId);
@@ -39,10 +71,22 @@ export function getCodexEffortVariants(
   }
 
   const normalizedModelId = stripCodexEffortSuffix(modelId);
-  const variantIds = [normalizedModelId];
+  const variantIds: string[] = [];
+
+  const appendVariantsForEffort = (effort: CodexEffort | undefined) => {
+    const effortModel = effort
+      ? applyCodexEffortSuffix(normalizedModelId, effort)
+      : normalizedModelId;
+    variantIds.push(effortModel);
+    for (const serviceTier of serviceTiers) {
+      variantIds.push(`${effortModel}-${serviceTier}`);
+    }
+  };
+
+  appendVariantsForEffort(undefined);
 
   for (const effort of CODEX_EFFORTS_IN_ORDER) {
-    variantIds.push(applyCodexEffortSuffix(normalizedModelId, effort));
+    appendVariantsForEffort(effort);
     if (effort === maxEffort) {
       break;
     }

ui/src/lib/model-catalogs.ts

@@ -266,6 +266,7 @@ export const MODEL_CATALOGS: Record<string, ProviderCatalog> = {
         description:
           'Newest Codex-released GPT-5 family model; falls back to GPT-5.4 on free plans',
         codexMaxEffort: 'xhigh',
+        codexServiceTiers: ['fast'],
         presetMapping: {
           default: 'gpt-5.5',
           opus: 'gpt-5.5',
@@ -278,6 +279,7 @@ export const MODEL_CATALOGS: Record<string, ProviderCatalog> = {
         name: 'GPT-5.4',
         description: 'Recommended Codex default for most coding and agentic tasks',
         codexMaxEffort: 'xhigh',
+        codexServiceTiers: ['fast'],
         presetMapping: {
           default: 'gpt-5.4',
           opus: 'gpt-5.4',

ui/tests/unit/components/cliproxy/provider-model-selector.test.tsx

@@ -123,11 +123,34 @@ describe('FlexibleModelSelector', () => {
 
     expect(screen.getByText('gpt-5.3-codex-high')).toBeInTheDocument();
     expect(screen.getByText('gpt-5.3-codex-xhigh')).toBeInTheDocument();
+    expect(screen.getByText('gpt-5.4-high-fast')).toBeInTheDocument();
 
     await userEvent.click(screen.getByText('gpt-5.3-codex-high'));
     expect(onChange).toHaveBeenCalledWith('gpt-5.3-codex-high');
   });
 
+  it('offers codex fast variants without relegating saved fast selections', async () => {
+    const onChange = vi.fn();
+
+    render(
+      <FlexibleModelSelector
+        label="Primary model"
+        value="gpt-5.4-high-fast"
+        onChange={onChange}
+        catalog={MODEL_CATALOGS.codex}
+        allModels={[]}
+      />
+    );
+
+    expect(screen.getByRole('button', { name: /gpt-5\.4-high-fast/i })).toBeInTheDocument();
+
+    await userEvent.click(screen.getByRole('button', { name: /gpt-5\.4-high-fast/i }));
+
+    expect(screen.queryByText('Current value')).not.toBeInTheDocument();
+    expect(screen.getByText('gpt-5.4-fast')).toBeInTheDocument();
+    expect(screen.getAllByText('gpt-5.4-high-fast').length).toBeGreaterThan(0);
+  });
+
   it('does not relegate saved codex effort variants to the legacy current-value fallback', async () => {
     render(
       <FlexibleModelSelector

ui/tests/unit/ui/lib/codex-effort.test.ts

@@ -4,12 +4,15 @@ import {
   getCodexEffortDisplay,
   getCodexEffortVariants,
   parseCodexEffort,
+  parseCodexServiceTier,
   stripCodexEffortSuffix,
 } from '@/lib/codex-effort';
 
 describe('parseCodexEffort', () => {
   it('parses lowercase suffixes', () => {
     expect(parseCodexEffort('gpt-5.3-codex-high')).toBe('high');
+    expect(parseCodexEffort('gpt-5.4-high-fast')).toBe('high');
+    expect(parseCodexEffort('gpt-5.4-fast-high')).toBe('high');
     expect(parseCodexEffort('gpt-5.3-codex-xhigh')).toBe('xhigh');
     expect(parseCodexEffort('gpt-5-mini-medium')).toBe('medium');
   });
@@ -21,10 +24,19 @@ describe('parseCodexEffort', () => {
   it('returns undefined for unsuffixed or unsupported values', () => {
     expect(parseCodexEffort('gpt-5.3-codex')).toBeUndefined();
     expect(parseCodexEffort('gpt-5.3-codex-low')).toBeUndefined();
+    expect(parseCodexEffort('gpt-5.4-fast')).toBeUndefined();
     expect(parseCodexEffort(undefined)).toBeUndefined();
   });
 });
 
+describe('parseCodexServiceTier', () => {
+  it('parses fast service-tier suffixes', () => {
+    expect(parseCodexServiceTier('gpt-5.4-fast')).toBe('fast');
+    expect(parseCodexServiceTier('gpt-5.4-high-fast')).toBe('fast');
+    expect(parseCodexServiceTier('gpt-5.4-fast-high')).toBe('fast');
+  });
+});
+
 describe('getCodexEffortDisplay', () => {
   it('returns pinned label for suffixed models', () => {
     expect(getCodexEffortDisplay('gpt-5.3-codex-high')).toEqual({
@@ -48,7 +60,9 @@ describe('getCodexEffortDisplay', () => {
 describe('codex effort helpers', () => {
   it('strips and reapplies codex effort suffixes', () => {
     expect(stripCodexEffortSuffix('gpt-5.3-codex-high')).toBe('gpt-5.3-codex');
+    expect(stripCodexEffortSuffix('gpt-5.4-fast-high')).toBe('gpt-5.4');
     expect(applyCodexEffortSuffix('gpt-5.3-codex-high', 'xhigh')).toBe('gpt-5.3-codex-xhigh');
+    expect(applyCodexEffortSuffix('gpt-5.4-fast', 'high')).toBe('gpt-5.4-high-fast');
     expect(applyCodexEffortSuffix('gpt-5.3-codex', undefined)).toBe('gpt-5.3-codex');
   });
 
@@ -65,4 +79,15 @@ describe('codex effort helpers', () => {
       'gpt-5.4-mini-high',
     ]);
   });
+
+  it('builds fast variants for models with a fast service tier', () => {
+    expect(getCodexEffortVariants('gpt-5.4', 'high', ['fast'])).toEqual([
+      'gpt-5.4',
+      'gpt-5.4-fast',
+      'gpt-5.4-medium',
+      'gpt-5.4-medium-fast',
+      'gpt-5.4-high',
+      'gpt-5.4-high-fast',
+    ]);
+  });
 });

ui/tests/unit/ui/lib/model-catalogs-codex.test.ts

@@ -14,8 +14,10 @@ describe('codex model catalog defaults', () => {
     expect(codex55?.tier).toBe('paid');
     expect(codex55?.presetMapping?.haiku).toBe('gpt-5.4-mini');
     expect(codex55?.codexMaxEffort).toBe('xhigh');
+    expect(codex55?.codexServiceTiers).toEqual(['fast']);
     expect(codex54?.tier).toBeUndefined();
     expect(codex54?.presetMapping?.haiku).toBe('gpt-5.4-mini');
+    expect(codex54?.codexServiceTiers).toEqual(['fast']);
     expect(codex53?.presetMapping?.haiku).toBe('gpt-5.4-mini');
     expect(codex52?.presetMapping?.haiku).toBe('gpt-5.4-mini');
     expect(codex53?.codexMaxEffort).toBe('xhigh');