diff --git a/vscode/src/sessions/sessionProfileInference.test.ts b/vscode/src/sessions/sessionProfileInference.test.ts
new file mode 100644
index 0000000..bb399fe
--- /dev/null
+++ b/vscode/src/sessions/sessionProfileInference.test.ts
@@ -0,0 +1,195 @@
+import { mkdtempSync, mkdirSync, rmSync, writeFileSync } from 'node:fs'
+import * as os from 'node:os'
+import * as path from 'node:path'
+import { afterEach, describe, expect, it } from 'vitest'
+import {
+  collectProfileModelIds,
+  extractLastAssistantModel,
+  inferProfilePathForSession,
+  matchProfilePathForModel,
+  normalizeModelId,
+} from './sessionProfileInference'
+
+const tempDirs: string[] = []
+
+afterEach(() => {
+  while (tempDirs.length > 0) {
+    const dir = tempDirs.pop()
+    if (dir)
+      rmSync(dir, { recursive: true, force: true })
+  }
+})
+
+function tempDir(prefix: string): string {
+  const dir = mkdtempSync(path.join(os.tmpdir(), prefix))
+  tempDirs.push(dir)
+  return dir
+}
+
+describe('normalizeModelId', () => {
+  it('小写并去掉 -build 后缀', () => {
+    expect(normalizeModelId('Grok-4.5-build')).toBe('grok-4.5')
+  })
+
+  it('去掉方括号后缀如 [1m]', () => {
+    expect(normalizeModelId('grok-4.5[1m]')).toBe('grok-4.5')
+  })
+
+  it('trim + 大小写 + 方括号 + -build 组合', () => {
+    expect(normalizeModelId('  Grok-4.5-build[1m]  ')).toBe('grok-4.5')
+  })
+
+  it('不剥离版本号本身', () => {
+    expect(normalizeModelId('claude-opus-4-20250514')).toBe('claude-opus-4-20250514')
+  })
+
+  it('不剥离 -preview', () => {
+    expect(normalizeModelId('model-preview')).toBe('model-preview')
+  })
+
+  it('折叠连续空白', () => {
+    expect(normalizeModelId('grok  4.5')).toBe('grok 4.5')
+  })
+})
+
+describe('extractLastAssistantModel', () => {
+  it('多条 assistant 取最后一条 message.model', () => {
+    const text = [
+      JSON.stringify({ type: 'assistant', message: { model: 'old-model' } }),
+      JSON.stringify({ type: 'user', message: 'hi' }),
+      JSON.stringify({ type: 'assistant', message: { model: 'grok-4.5-build' } }),
+    ].join('\n')
+    expect(extractLastAssistantModel(text)).toBe('grok-4.5-build')
+  })
+
+  it('无 assistant model 返回 null', () => {
+    const text = [
+      JSON.stringify({ type: 'user', message: 'hi' }),
+      JSON.stringify({ type: 'assistant', message: { content: 'yo' } }),
+    ].join('\n')
+    expect(extractLastAssistantModel(text)).toBeNull()
+  })
+
+  it('message.model 为空字符串忽略', () => {
+    const text = JSON.stringify({ type: 'assistant', message: { model: '  ' } })
+    expect(extractLastAssistantModel(text)).toBeNull()
+  })
+
+  it('非法 json 行跳过', () => {
+    const text = [
+      'not-json',
+      JSON.stringify({ type: 'assistant', message: { model: 'ok-model' } }),
+      '{broken',
+    ].join('\n')
+    expect(extractLastAssistantModel(text)).toBe('ok-model')
+  })
+})
+
+describe('collectProfileModelIds', () => {
+  it('从 env 收集已知 model 字段的非空字符串', () => {
+    const ids = collectProfileModelIds({
+      env: {
+        ANTHROPIC_MODEL: 'grok-4.5[1m]',
+        ANTHROPIC_DEFAULT_OPUS_MODEL: 'opus-x',
+        ANTHROPIC_DEFAULT_SONNET_MODEL: '',
+        ANTHROPIC_DEFAULT_HAIKU_MODEL: '  ',
+        ANTHROPIC_SMALL_FAST_MODEL: 'haiku-fast',
+        OTHER: 'ignore',
+      },
+    })
+    expect(ids).toEqual(['grok-4.5[1m]', 'opus-x', 'haiku-fast'])
+  })
+
+  it('无 env 或非法结构返回空数组', () => {
+    expect(collectProfileModelIds(null)).toEqual([])
+    expect(collectProfileModelIds({})).toEqual([])
+    expect(collectProfileModelIds({ env: 'bad' })).toEqual([])
+  })
+})
+
+describe('matchProfilePathForModel', () => {
+  const grok = '/profiles/grok-4.5.json'
+  const official = '/profiles/offical.json'
+  const other = '/profiles/other.json'
+
+  it('唯一 normalize 命中返回 path', () => {
+    const path_ = matchProfilePathForModel('grok-4.5-build', [
+      { path: official, modelIds: [] },
+      { path: grok, modelIds: ['grok-4.5[1m]'] },
+    ])
+    expect(path_).toBe(grok)
+  })
+
+  it('零命中返回 null', () => {
+    expect(matchProfilePathForModel('claude-opus-4', [
+      { path: grok, modelIds: ['grok-4.5[1m]'] },
+      { path: official, modelIds: [] },
+    ])).toBeNull()
+  })
+
+  it('多个不同 path 命中返回 null（歧义）', () => {
+    expect(matchProfilePathForModel('shared-model', [
+      { path: grok, modelIds: ['shared-model'] },
+      { path: other, modelIds: ['SHARED-MODEL'] },
+    ])).toBeNull()
+  })
+
+  it('同一 path 多 modelIds 命中仍唯一', () => {
+    expect(matchProfilePathForModel('m1', [
+      { path: grok, modelIds: ['m1', 'm1-alt'] },
+    ])).toBe(grok)
+  })
+})
+
+describe('inferProfilePathForSession', () => {
+  it('jsonl grok model 唯一匹配 grok profile', async () => {
+    const projectsDir = tempDir('infer-proj-')
+    const profilesDir = tempDir('infer-prof-')
+    const sessionId = 'sess-grok'
+
+    writeFileSync(
+      path.join(projectsDir, `${sessionId}.jsonl`),
+      [
+        JSON.stringify({ type: 'user', message: 'hi' }),
+        JSON.stringify({ type: 'assistant', message: { model: 'grok-4.5-build' } }),
+      ].join('\n'),
+    )
+
+    const grokPath = path.join(profilesDir, 'grok-4.5.json')
+    writeFileSync(grokPath, JSON.stringify({
+      env: { ANTHROPIC_MODEL: 'grok-4.5[1m]' },
+    }))
+    writeFileSync(path.join(profilesDir, 'offical.json'), JSON.stringify({
+      env: {},
+    }))
+
+    const inferred = await inferProfilePathForSession(sessionId, projectsDir, profilesDir)
+    expect(inferred).toBe(grokPath)
+  })
+
+  it('会话文件缺失返回 null', async () => {
+    const projectsDir = tempDir('infer-miss-')
+    const profilesDir = tempDir('infer-miss-p-')
+    mkdirSync(profilesDir, { recursive: true })
+    expect(await inferProfilePathForSession('no-such', projectsDir, profilesDir)).toBeNull()
+  })
+
+  it('无唯一匹配返回 null', async () => {
+    const projectsDir = tempDir('infer-amb-')
+    const profilesDir = tempDir('infer-amb-p-')
+    const sessionId = 'sess-x'
+
+    writeFileSync(
+      path.join(projectsDir, `${sessionId}.jsonl`),
+      JSON.stringify({ type: 'assistant', message: { model: 'shared' } }),
+    )
+    writeFileSync(path.join(profilesDir, 'a.json'), JSON.stringify({
+      env: { ANTHROPIC_MODEL: 'shared' },
+    }))
+    writeFileSync(path.join(profilesDir, 'b.json'), JSON.stringify({
+      env: { ANTHROPIC_MODEL: 'shared' },
+    }))
+
+    expect(await inferProfilePathForSession(sessionId, projectsDir, profilesDir)).toBeNull()
+  })
+})
diff --git a/vscode/src/sessions/sessionProfileInference.ts b/vscode/src/sessions/sessionProfileInference.ts
new file mode 100644
index 0000000..416af35
--- /dev/null
+++ b/vscode/src/sessions/sessionProfileInference.ts
@@ -0,0 +1,149 @@
+import { readdir, readFile } from 'node:fs/promises'
+import * as path from 'node:path'
+import { getProfilesDir } from '../cc/profiles'
+
+/** 归一化 model id：小写、去 [1m]、去 -build；保留主版本号 */
+export function normalizeModelId(raw: string): string {
+  let s = raw.trim().toLowerCase()
+  s = s.replace(/\[[^\]]*\]/g, '')
+  s = s.replace(/-build$/, '')
+  s = s.replace(/\s+/g, ' ').trim()
+  return s
+}
+
+/** 从 JSONL 全文取「最后一个」assistant.message.model；无则 null */
+export function extractLastAssistantModel(jsonlText: string): string | null {
+  let last: string | null = null
+  const lines = jsonlText.split(/\r?\n/)
+  for (const line of lines) {
+    const trimmed = line.trim()
+    if (!trimmed)
+      continue
+    let parsed: unknown
+    try {
+      parsed = JSON.parse(trimmed)
+    }
+    catch {
+      continue
+    }
+    if (!parsed || typeof parsed !== 'object')
+      continue
+    const rec = parsed as { type?: unknown, message?: unknown }
+    if (rec.type !== 'assistant')
+      continue
+    if (!rec.message || typeof rec.message !== 'object')
+      continue
+    const model = (rec.message as { model?: unknown }).model
+    if (typeof model !== 'string')
+      continue
+    const value = model.trim()
+    if (!value)
+      continue
+    last = value
+  }
+  return last
+}
+
+const PROFILE_MODEL_ENV_KEYS = [
+  'ANTHROPIC_MODEL',
+  'ANTHROPIC_DEFAULT_OPUS_MODEL',
+  'ANTHROPIC_DEFAULT_SONNET_MODEL',
+  'ANTHROPIC_DEFAULT_HAIKU_MODEL',
+  'ANTHROPIC_SMALL_FAST_MODEL',
+] as const
+
+/**
+ * 读 profile JSON 的 env 字段，收集可匹配的 model 字符串。
+ * 仅字符串且非空才纳入。
+ */
+export function collectProfileModelIds(profileJson: unknown): string[] {
+  if (!profileJson || typeof profileJson !== 'object')
+    return []
+  const env = (profileJson as { env?: unknown }).env
+  if (!env || typeof env !== 'object')
+    return []
+  const rec = env as Record<string, unknown>
+  const ids: string[] = []
+  for (const key of PROFILE_MODEL_ENV_KEYS) {
+    const value = rec[key]
+    if (typeof value !== 'string')
+      continue
+    const trimmed = value.trim()
+    if (!trimmed)
+      continue
+    ids.push(value)
+  }
+  return ids
+}
+
+/**
+ * 给定 transcript model + profiles 列表，normalize 后精确匹配：
+ * 唯一 path → 返回该 path；0 或多个 → null
+ */
+export function matchProfilePathForModel(
+  transcriptModel: string,
+  profiles: Array<{ path: string, modelIds: string[] }>,
+): string | null {
+  const target = normalizeModelId(transcriptModel)
+  if (!target)
+    return null
+
+  const matched = new Set<string>()
+  for (const profile of profiles) {
+    for (const id of profile.modelIds) {
+      if (normalizeModelId(id) === target) {
+        matched.add(profile.path)
+        break
+      }
+    }
+  }
+
+  if (matched.size !== 1)
+    return null
+  return matched.values().next().value ?? null
+}
+
+/**
+ * 读 session JSONL + 扫描 profilesDir 下 *.json，
+ * 返回唯一匹配的 profile 绝对路径，否则 null。
+ * IO 失败返回 null。
+ */
+export async function inferProfilePathForSession(
+  sessionId: string,
+  projectsDir: string,
+  profilesDir?: string,
+): Promise<string | null> {
+  try {
+    const sessionPath = path.join(projectsDir, `${sessionId}.jsonl`)
+    const jsonlText = await readFile(sessionPath, 'utf8')
+    const transcriptModel = extractLastAssistantModel(jsonlText)
+    if (!transcriptModel)
+      return null
+
+    const dir = profilesDir ?? getProfilesDir()
+    const entries = await readdir(dir)
+    const profiles: Array<{ path: string, modelIds: string[] }> = []
+    for (const name of entries) {
+      if (!name.endsWith('.json'))
+        continue
+      const profilePath = path.join(dir, name)
+      try {
+        const raw = await readFile(profilePath, 'utf8')
+        const parsed: unknown = JSON.parse(raw)
+        profiles.push({
+          path: profilePath,
+          modelIds: collectProfileModelIds(parsed),
+        })
+      }
+      catch {
+        // 跳过坏 profile，继续扫描其余
+        continue
+      }
+    }
+
+    return matchProfilePathForModel(transcriptModel, profiles)
+  }
+  catch {
+    return null
+  }
+}