diff --git a/src/kernel/profile.ts b/src/kernel/profile.ts
new file mode 100644
index 0000000..7b2fa3e
--- /dev/null
+++ b/src/kernel/profile.ts
@@ -0,0 +1,172 @@
+import { readFile } from "node:fs/promises"
+import { join } from "node:path"
+
+/** AGENTS.md 中 Project Profile 区块的固定标题 */
+export const PROFILE_SECTION_TITLE = "## Project Profile"
+
+export type TddDefaultMode = "strict" | "relaxed" | "bypass"
+
+/** 解析后的结构化项目 Profile（只含可机检字段） */
+export interface ProjectProfile {
+  testCommand: string | null
+  regressionCommand: string | null
+  testFilePatterns: string[]
+  implementationFilePatterns: string[]
+  tddDefaultMode: TddDefaultMode | null
+  versionBumpRule: string | null
+  versionFile: string | null
+  tagFormat: string | null
+  releaseWorkflowPath: string | null
+  riskPatterns: string[]
+}
+
+export interface ProfileParseResult {
+  profile: ProjectProfile
+  warnings: string[]
+}
+
+/** 无 Profile 时的空值：所有可选字段为 null、列表字段为空数组 */
+export function emptyProfile(): ProjectProfile {
+  return {
+    testCommand: null,
+    regressionCommand: null,
+    testFilePatterns: [],
+    implementationFilePatterns: [],
+    tddDefaultMode: null,
+    versionBumpRule: null,
+    versionFile: null,
+    tagFormat: null,
+    releaseWorkflowPath: null,
+    riskPatterns: [],
+  }
+}
+
+/** 条目行：`- key: value`，key 仅含小写字母/数字/空格/下划线/连字符 */
+const KEY_VALUE_PATTERN = /^- ([a-z0-9 _-]+):\s*(.+)$/
+
+const VALID_TDD_MODES = new Set<string>(["strict", "relaxed", "bypass"])
+
+/**
+ * 解析 markdown 中的 `## Project Profile` 区块。
+ * 定位标题到下一个 `##` 标题之间的条目行，按白名单提取；
+ * 未知 key 记 warning（不阻断），重复 key 取最后（文档语义）。
+ */
+export function parseProjectProfile(markdown: string): ProfileParseResult {
+  const profile = emptyProfile()
+  const warnings: string[] = []
+  const section = findProfileSection(markdown)
+  if (!section) {
+    return { profile, warnings }
+  }
+
+  const lines = markdown.split("\n")
+  for (let i = section.start + 1; i < section.end; i++) {
+    const match = KEY_VALUE_PATTERN.exec(lines[i])
+    if (!match) continue
+    applyKey(profile, warnings, match[1], cleanValue(match[2]))
+  }
+  return { profile, warnings }
+}
+
+/** 从项目根目录读取 AGENTS.md 并解析；文件缺失或区块缺失返回空 Profile，不抛错 */
+export async function readProjectProfile(projectDir: string): Promise<ProjectProfile> {
+  let markdown: string
+  try {
+    markdown = await readFile(join(projectDir, "AGENTS.md"), "utf8")
+  } catch {
+    return emptyProfile()
+  }
+  return parseProjectProfile(markdown).profile
+}
+
+/**
+ * 确认回写辅助：将 profileBlock（完整 `## Project Profile` 区块）写入 markdown。
+ * 已存在区块则整块替换，否则追加到末尾。
+ */
+export function upsertProjectProfile(markdown: string, profileBlock: string): string {
+  const section = findProfileSection(markdown)
+  if (!section) {
+    const trimmed = markdown.trimEnd()
+    if (trimmed === "") return profileBlock.trimStart()
+    return `${trimmed}\n\n${profileBlock}`
+  }
+
+  const lines = markdown.split("\n")
+  const before = lines.slice(0, section.start).join("\n").trimEnd()
+  const after = lines.slice(section.end).join("\n").trimStart()
+  return [before, profileBlock.trim(), after].filter(part => part !== "").join("\n\n")
+}
+
+/** 定位 Profile 区块：标题行索引与结束行索引（下一个 `##` 标题，含；无则到文件末尾） */
+function findProfileSection(markdown: string): { start: number; end: number } | null {
+  const lines = markdown.split("\n")
+  const start = lines.findIndex(line => line.trim() === PROFILE_SECTION_TITLE)
+  if (start === -1) return null
+
+  let end = lines.length
+  for (let i = start + 1; i < lines.length; i++) {
+    if (/^#{2,}\s/.test(lines[i])) {
+      end = i
+      break
+    }
+  }
+  return { start, end }
+}
+
+/** 去掉值中的反引号与两端空白 */
+function cleanValue(raw: string): string {
+  return raw.replaceAll("`", "").trim()
+}
+
+/** 逗号分隔的模式列表：trim 并过滤空项 */
+function splitPatterns(value: string): string[] {
+  return value
+    .split(",")
+    .map(part => part.trim())
+    .filter(part => part !== "")
+}
+
+function applyKey(profile: ProjectProfile, warnings: string[], key: string, value: string): void {
+  switch (key) {
+    case "test command":
+      profile.testCommand = value
+      return
+    case "regression command":
+      profile.regressionCommand = value
+      return
+    case "test file patterns":
+      profile.testFilePatterns = splitPatterns(value)
+      return
+    case "implementation file patterns":
+      profile.implementationFilePatterns = splitPatterns(value)
+      return
+    case "tdd default mode":
+      if (VALID_TDD_MODES.has(value)) {
+        profile.tddDefaultMode = value as TddDefaultMode
+      } else {
+        warnings.push(`Invalid tdd default mode: ${value}`)
+      }
+      return
+    case "version bump rule":
+      profile.versionBumpRule = value
+      return
+    case "version file":
+      profile.versionFile = value
+      return
+    case "tag format":
+      if (value.includes("{version}")) {
+        profile.tagFormat = value
+      } else {
+        warnings.push(`tag format must contain {version} placeholder: ${value}`)
+      }
+      return
+    case "release workflow":
+      profile.releaseWorkflowPath = value
+      return
+    case "risk patterns":
+      profile.riskPatterns = splitPatterns(value)
+      return
+    default:
+      warnings.push(`Unknown profile key: ${key}`)
+  }
+}
diff --git a/test/kernel/profile.test.ts b/test/kernel/profile.test.ts
new file mode 100644
index 0000000..ec9bef7
--- /dev/null
+++ b/test/kernel/profile.test.ts
@@ -0,0 +1,178 @@
+import { describe, it, expect } from "vitest"
+import { mkdtemp, writeFile, rm } from "node:fs/promises"
+import { tmpdir } from "node:os"
+import { join } from "node:path"
+import {
+  parseProjectProfile,
+  readProjectProfile,
+  upsertProjectProfile,
+  emptyProfile,
+  PROFILE_SECTION_TITLE,
+} from "../../src/kernel/profile.js"
+
+const FULL_BLOCK = `## Project Profile
+
+- test command: \`npm test -- run\`
+- regression command: \`npm run test:regression\`
+- test file patterns: \`test/**/*.test.ts\`
+- implementation file patterns: \`src/**/*.ts\`
+- tdd default mode: \`strict\`
+- version bump rule: \`breaking→major, feature→minor, fix→patch\`
+- version file: \`package.json\`
+- tag format: \`v{version}\`
+- release workflow: \`.github/workflows/release.yml\`
+- risk patterns: \`migrations/**, **/auth/**, **/permissions/**\`
+`
+
+describe("parseProjectProfile", () => {
+  it("parses a well-formed profile section into structured fields", () => {
+    const { profile, warnings } = parseProjectProfile(FULL_BLOCK)
+    expect(warnings).toEqual([])
+    expect(profile).toEqual({
+      testCommand: "npm test -- run",
+      regressionCommand: "npm run test:regression",
+      testFilePatterns: ["test/**/*.test.ts"],
+      implementationFilePatterns: ["src/**/*.ts"],
+      tddDefaultMode: "strict",
+      versionBumpRule: "breaking→major, feature→minor, fix→patch",
+      versionFile: "package.json",
+      tagFormat: "v{version}",
+      releaseWorkflowPath: ".github/workflows/release.yml",
+      riskPatterns: ["migrations/**", "**/auth/**", "**/permissions/**"],
+    })
+  })
+
+  it("stops at the next heading, ignoring later content", () => {
+    const markdown = `${FULL_BLOCK}\n## Other Section\n\n- test command: \`ignored\`\n`
+    const { profile } = parseProjectProfile(markdown)
+    expect(profile.testCommand).toBe("npm test -- run")
+  })
+
+  it("strips backticks and surrounding whitespace from values", () => {
+    const markdown = "## Project Profile\n\n- test command: `  npm test -- run  `\n"
+    const { profile } = parseProjectProfile(markdown)
+    expect(profile.testCommand).toBe("npm test -- run")
+  })
+
+  it("splits comma-separated pattern lists", () => {
+    const markdown = "## Project Profile\n\n- implementation file patterns: `src/**/*.ts, src/kernel/**/*.ts, src/util/**/*.ts`\n"
+    const { profile } = parseProjectProfile(markdown)
+    expect(profile.implementationFilePatterns).toEqual([
+      "src/**/*.ts",
+      "src/kernel/**/*.ts",
+      "src/util/**/*.ts",
+    ])
+  })
+
+  it("reports unknown keys as warnings without blocking known keys", () => {
+    const markdown = "## Project Profile\n\n- mystery key: `value`\n- test command: `npm test`\n"
+    const { profile, warnings } = parseProjectProfile(markdown)
+    expect(profile.testCommand).toBe("npm test")
+    expect(warnings).toEqual(["Unknown profile key: mystery key"])
+  })
+
+  it("takes the last value when a key is repeated", () => {
+    const markdown = "## Project Profile\n\n- test command: `first`\n- test command: `second`\n"
+    const { profile } = parseProjectProfile(markdown)
+    expect(profile.testCommand).toBe("second")
+  })
+
+  it("rejects a tag format without the {version} placeholder", () => {
+    const markdown = "## Project Profile\n\n- tag format: `v1.0`\n"
+    const { profile, warnings } = parseProjectProfile(markdown)
+    expect(profile.tagFormat).toBeNull()
+    expect(warnings.some(w => w.includes("tag format"))).toBe(true)
+  })
+
+  it("rejects an invalid tdd default mode", () => {
+    const markdown = "## Project Profile\n\n- tdd default mode: `sometimes`\n"
+    const { profile, warnings } = parseProjectProfile(markdown)
+    expect(profile.tddDefaultMode).toBeNull()
+    expect(warnings.some(w => w.includes("tdd default mode"))).toBe(true)
+  })
+
+  it("skips malformed lines without throwing", () => {
+    const markdown = [
+      "## Project Profile",
+      "",
+      "this is not a key-value line",
+      "- ",
+      "- test command:",
+      "- broken key with ! char: `x`",
+      "- test command: `npm test`",
+    ].join("\n")
+    const { profile, warnings } = parseProjectProfile(markdown)
+    expect(profile.testCommand).toBe("npm test")
+    expect(warnings).toEqual([])
+  })
+
+  it("returns an empty profile with no warnings when the section is missing", () => {
+    const { profile, warnings } = parseProjectProfile("# Just a title\n\nsome text\n")
+    expect(profile).toEqual(emptyProfile())
+    expect(warnings).toEqual([])
+  })
+
+  it("returns an empty profile when the section has no entries", () => {
+    const { profile } = parseProjectProfile(`${PROFILE_SECTION_TITLE}\n`)
+    expect(profile).toEqual(emptyProfile())
+  })
+})
+
+describe("readProjectProfile", () => {
+  async function withProjectDir(agentMd: string | null, fn: (dir: string) => Promise<void>) {
+    const dir = await mkdtemp(join(tmpdir(), "cabbage-profile-"))
+    try {
+      if (agentMd !== null) {
+        await writeFile(join(dir, "AGENTS.md"), agentMd)
+      }
+      await fn(dir)
+    } finally {
+      await rm(dir, { recursive: true, force: true })
+    }
+  }
+
+  it("returns an empty profile when AGENTS.md does not exist", async () => {
+    await withProjectDir(null, async dir => {
+      await expect(readProjectProfile(dir)).resolves.toEqual(emptyProfile())
+    })
+  })
+
+  it("parses AGENTS.md when the profile section exists", async () => {
+    await withProjectDir(FULL_BLOCK, async dir => {
+      const profile = await readProjectProfile(dir)
+      expect(profile.testCommand).toBe("npm test -- run")
+      expect(profile.tagFormat).toBe("v{version}")
+      expect(profile.riskPatterns).toEqual(["migrations/**", "**/auth/**", "**/permissions/**"])
+    })
+  })
+
+  it("returns an empty profile when AGENTS.md lacks the section", async () => {
+    await withProjectDir("# Rules\n\n- keep it simple\n", async dir => {
+      await expect(readProjectProfile(dir)).resolves.toEqual(emptyProfile())
+    })
+  })
+})
+
+describe("upsertProjectProfile", () => {
+  const block = FULL_BLOCK.trimEnd()
+
+  it("appends the block to markdown without a profile section", () => {
+    const markdown = "# Project Rules\n\n- be concise\n"
+    const result = upsertProjectProfile(markdown, block)
+    expect(result.startsWith(markdown.trimEnd())).toBe(true)
+    expect(result).toContain(`\n\n${block}`)
+  })
+
+  it("returns the block alone for empty markdown", () => {
+    expect(upsertProjectProfile("", block)).toBe(block)
+  })
+
+  it("replaces the existing profile section and keeps surrounding content", () => {
+    const markdown = `# Project Rules\n\n- be concise\n\n## Project Profile\n\n- test command: \`old\`\n\n## Other Section\n\nkeep me`
+    const result = upsertProjectProfile(markdown, block)
+    expect(result).toContain("# Project Rules\n\n- be concise")
+    expect(result).toContain("## Other Section\n\nkeep me")
+    expect(result).not.toContain("old")
+    expect(result).toContain(block)
+  })
+})