fix: /context command to display the correct context window for gpt

src/server/__tests__/proxy-streaming.test.ts

@@ -281,6 +281,12 @@ describe('openaiResponsesStreamToAnthropic', () => {
     const texts = textDeltas.map((e) => (e.data.delta as Record<string, unknown>).text)
     expect(texts).toContain('Hello')
     expect(texts).toContain(' world')
+
+    const msgDelta = events.find((e) => e.event === 'message_delta')!
+    expect(msgDelta.data.usage).toEqual({
+      input_tokens: 10,
+      output_tokens: 5,
+    })
   })
 
   test('function call streaming', async () => {

src/server/proxy/streaming/openaiResponsesStreamToAnthropic.ts

@@ -265,7 +265,10 @@ function processEvent(
       controller.enqueue(encoder.encode(formatSse('message_delta', {
         type: 'message_delta',
         delta: { stop_reason: stopReason, stop_sequence: null },
-        usage: { output_tokens: usage?.output_tokens ?? 0 },
+        usage: {
+          input_tokens: usage?.input_tokens ?? 0,
+          output_tokens: usage?.output_tokens ?? 0,
+        },
       })))
       if (!state.messageStopped) {
         state.messageStopped = true

src/services/openaiAuth/models.test.ts

@@ -1,6 +1,9 @@
 import { describe, expect, test } from 'bun:test'
 import {
   OPENAI_DEFAULT_MAIN_MODEL,
+  OPENAI_GPT5_LARGE_CONTEXT_WINDOW,
+  OPENAI_GPT5_STANDARD_CONTEXT_WINDOW,
+  getOpenAIContextWindowForModel,
   isOpenAIResponsesModel,
   resolveOpenAICodexModel,
 } from './models.js'
@@ -18,4 +21,22 @@ describe('openai auth model resolution', () => {
   test('maps opus aliases to the OpenAI default model', () => {
     expect(resolveOpenAICodexModel('opus')).toBe(OPENAI_DEFAULT_MAIN_MODEL)
   })
+
+  test('maps large-context GPT-5 models to a 1.05M context window', () => {
+    expect(getOpenAIContextWindowForModel('gpt-5.5')).toBe(
+      OPENAI_GPT5_LARGE_CONTEXT_WINDOW,
+    )
+    expect(getOpenAIContextWindowForModel('gpt-5.4')).toBe(
+      OPENAI_GPT5_LARGE_CONTEXT_WINDOW,
+    )
+  })
+
+  test('maps standard GPT-5 models to a 400k context window', () => {
+    expect(getOpenAIContextWindowForModel('gpt-5.3-codex')).toBe(
+      OPENAI_GPT5_STANDARD_CONTEXT_WINDOW,
+    )
+    expect(getOpenAIContextWindowForModel('gpt-5.4-mini')).toBe(
+      OPENAI_GPT5_STANDARD_CONTEXT_WINDOW,
+    )
+  })
 })

src/services/openaiAuth/models.ts

@@ -1,6 +1,8 @@
 export const OPENAI_DEFAULT_MAIN_MODEL = 'gpt-5.3-codex'
 export const OPENAI_DEFAULT_SONNET_MODEL = 'gpt-5.4'
 export const OPENAI_DEFAULT_HAIKU_MODEL = 'gpt-5.4-mini'
+export const OPENAI_GPT5_STANDARD_CONTEXT_WINDOW = 400_000
+export const OPENAI_GPT5_LARGE_CONTEXT_WINDOW = 1_050_000
 
 export type OpenAIModelCatalogEntry = {
   value: string
@@ -98,3 +100,38 @@ export function getOpenAIModelDisplayName(model: string): string | null {
       return null
   }
 }
+
+export function getOpenAIContextWindowForModel(model: string): number | null {
+  const normalized = model.trim().toLowerCase()
+
+  // Current OpenAI model docs split GPT-5-family context windows into
+  // standard 400k models and larger 1.05M models.
+  if (
+    normalized === 'gpt-5.5' ||
+    normalized === 'gpt-5.5-pro' ||
+    normalized === 'gpt-5.4' ||
+    normalized === 'gpt-5.4-pro'
+  ) {
+    return OPENAI_GPT5_LARGE_CONTEXT_WINDOW
+  }
+
+  if (
+    normalized === 'gpt-5.4-mini' ||
+    normalized === 'gpt-5.4-nano' ||
+    normalized === 'gpt-5.3-codex' ||
+    normalized === 'gpt-5.2' ||
+    normalized === 'gpt-5.2-codex' ||
+    normalized === 'gpt-5.1' ||
+    normalized === 'gpt-5.1-codex' ||
+    normalized === 'gpt-5.1-codex-max' ||
+    normalized === 'gpt-5.1-codex-mini' ||
+    normalized === 'gpt-5-codex' ||
+    normalized === 'gpt-5' ||
+    normalized === 'gpt-5-mini' ||
+    normalized === 'gpt-5-nano'
+  ) {
+    return OPENAI_GPT5_STANDARD_CONTEXT_WINDOW
+  }
+
+  return null
+}

src/utils/__tests__/tokens.test.ts

@@ -0,0 +1,42 @@
+import { describe, expect, test } from 'bun:test'
+import { getCurrentUsage } from '../tokens.js'
+
+describe('getCurrentUsage', () => {
+  test('skips zero placeholder usage and returns the latest meaningful usage', () => {
+    const messages = [
+      {
+        type: 'assistant',
+        message: {
+          model: 'gpt-5.5',
+          content: [{ type: 'text', text: 'older' }],
+          usage: {
+            input_tokens: 123,
+            output_tokens: 45,
+            cache_creation_input_tokens: 6,
+            cache_read_input_tokens: 7,
+          },
+        },
+      },
+      {
+        type: 'assistant',
+        message: {
+          model: 'gpt-5.5',
+          content: [{ type: 'text', text: 'placeholder' }],
+          usage: {
+            input_tokens: 0,
+            output_tokens: 0,
+            cache_creation_input_tokens: 0,
+            cache_read_input_tokens: 0,
+          },
+        },
+      },
+    ] as const
+
+    expect(getCurrentUsage(messages as never)).toEqual({
+      input_tokens: 123,
+      output_tokens: 45,
+      cache_creation_input_tokens: 6,
+      cache_read_input_tokens: 7,
+    })
+  })
+})

src/utils/context.ts

@@ -1,11 +1,12 @@
 // biome-ignore-all assist/source/organizeImports: ANT-ONLY import markers must not be reordered
 import { CONTEXT_1M_BETA_HEADER } from '../constants/betas.js'
+import { getOpenAIContextWindowForModel } from '../services/openaiAuth/models.js'
 import { getGlobalConfig } from './config.js'
 import { isEnvTruthy } from './envUtils.js'
 import { getCanonicalName } from './model/model.js'
 import { getModelCapability } from './model/modelCapabilities.js'
 
-// Model context window size (200k tokens for all models right now)
+// Default fallback when the model-specific capability is unknown.
 export const MODEL_CONTEXT_WINDOW_DEFAULT = 200_000
 
 // Maximum output tokens for compact operations
@@ -71,6 +72,11 @@ export function getContextWindowForModel(
     return 1_000_000
   }
 
+  const openAIContextWindow = getOpenAIContextWindowForModel(model)
+  if (openAIContextWindow) {
+    return openAIContextWindow
+  }
+
   const cap = getModelCapability(model)
   if (cap?.max_input_tokens && cap.max_input_tokens >= 100_000) {
     if (

src/utils/tokens.ts

@@ -145,12 +145,30 @@ export function getCurrentUsage(messages: Message[]): {
     const message = messages[i]
     const usage = message ? getTokenUsage(message) : undefined
     if (usage) {
-      return {
+      const normalizedUsage = {
         input_tokens: usage.input_tokens,
         output_tokens: usage.output_tokens,
         cache_creation_input_tokens: usage.cache_creation_input_tokens ?? 0,
         cache_read_input_tokens: usage.cache_read_input_tokens ?? 0,
       }
+
+      // Zero-token usage is used in a few recovery/compaction paths as a
+      // placeholder for "stale or unavailable", not as a real token count.
+      if (
+        normalizedUsage.input_tokens === 0 &&
+        normalizedUsage.output_tokens === 0 &&
+        normalizedUsage.cache_creation_input_tokens === 0 &&
+        normalizedUsage.cache_read_input_tokens === 0
+      ) {
+        continue
+      }
+
+      return {
+        input_tokens: normalizedUsage.input_tokens,
+        output_tokens: normalizedUsage.output_tokens,
+        cache_creation_input_tokens: normalizedUsage.cache_creation_input_tokens,
+        cache_read_input_tokens: normalizedUsage.cache_read_input_tokens,
+      }
     }
   }
   return null