refactor(session): fold the session family into packages/session/

git mv the 12 packages from session-persistence/, session-projection/,
session-title/, and telemetry/ into one session/ group per the
regrouping RFC; merge the four group READMEs into one bilingual
triplet; rewrite the group segment in tsconfig references (intra-group
references shorten to ../<pkg>), tsconfig.base.json paths/globs,
knip.json keys, vitest include, gate scripts, and authored doc/note
citations; regenerate module graph, doc graphs, catalogs, and the
lockfile importer keys. No npm names change.

Full unit suite: 8779 passed; the 18 reported failures reproduce as
env flakes (ambient-proxy IPv6 tunneling, watched-dir inotify
timeouts under parallel load) — each passes in isolation with
NO_PROXY set, matching their known pre-existing behavior on master.

packages/session/session-title/tests/session-title.spec.ts

@@ -0,0 +1,162 @@
+import { createUserMessage } from '@deepseek-ai/dsh-llm'
+import { Context } from 'cordis'
+import { describe, expect, it } from 'vitest'
+import SessionStore, { Session, SessionId } from '@deepseek-ai/dsh-session'
+import SessionTitleService, {
+  SessionTitleProviderId,
+  fallbackSessionTitle,
+  foldSessionTitle,
+  normalizeSessionTitle,
+  truncateTitleUtf8,
+} from '@deepseek-ai/dsh-session-title'
+
+const CONFIG = {
+  fallbackMaxWords: 5,
+  fallbackMaxBytes: 40,
+  maxTitleBytes: 80,
+} as const
+
+async function settleTitles(): Promise<void> {
+  await new Promise(resolve => setTimeout(resolve, 0))
+}
+
+describe('session title normalization', () => {
+  it('removes terminal controls, collapses whitespace, and applies word and UTF-8 byte caps', () => {
+    expect(normalizeSessionTitle('\u001B]0;stolen\u0007  Hello\t brave\nnew world  ', 80))
+      .toBe('Hello brave new world')
+    expect(fallbackSessionTitle('one two three four', 3, 80)).toBe('one two three')
+    expect(fallbackSessionTitle('你好世界', 5, 7)).toBe('你好')
+    expect(Buffer.byteLength(fallbackSessionTitle('😀😀', 5, 5), 'utf8')).toBe(4)
+  })
+
+  it('rejects non-positive and fractional public limits', () => {
+    expect(() => truncateTitleUtf8('title', 0)).toThrow(/maxBytes must be a positive integer/)
+    expect(() => fallbackSessionTitle('title', 1.5, 10)).toThrow(/maxWords must be a positive integer/)
+  })
+})
+
+describe('SessionTitleService', () => {
+  it('logs and folds an immediate fallback after the first eligible human text message', async () => {
+    const ctx = new Context()
+    await ctx.plugin(SessionStore)
+    await ctx.plugin(SessionTitleService, CONFIG)
+    const session = ctx.sessions.create(SessionId('fresh'))
+    session.append('turn/start', {
+      turn: 1,
+    })
+    const message = session.append('user/message', createUserMessage({
+      content: [{ type: 'text', text: '  Build\nlog-backed session titles please  ' }],
+      source: { kind: 'user' },
+    }), { surfaceOp: 'append' })
+
+    await settleTitles()
+
+    const titleEvent = session.events.findLast(event => event.type === 'session/title')
+    expect(titleEvent).toMatchObject({
+      type: 'session/title',
+      seq: 2,
+      data: {
+        title: 'Build log-backed session titles please',
+        messageSeqs: [message.seq],
+        source: { kind: 'fallback' },
+      },
+    })
+    expect(ctx.sessionTitle.get(session)).toEqual({
+      title: 'Build log-backed session titles please',
+      messageSeqs: [message.seq],
+      source: { kind: 'fallback' },
+      eventSeq: 2,
+      updatedAt: titleEvent?.time,
+    })
+    expect(session.deriveMessages()).toHaveLength(1)
+    expect(session.surface.nodes).toEqual([message.seq])
+  })
+
+  it('derives a fallback title from the direct prompt instead of baked prefix context', async () => {
+    const ctx = new Context()
+    await ctx.plugin(SessionStore)
+    await ctx.plugin(SessionTitleService, CONFIG)
+    const session = ctx.sessions.create(SessionId('prefixed-title'))
+    session.append('turn/start', {
+      turn: 1,
+    })
+    session.append('user/message', createUserMessage({
+      content: [{ type: 'text', text: 'Explain this referenced session' }],
+      source: { kind: 'user' },
+    }), { surfaceOp: 'append' })
+
+    await settleTitles()
+
+    expect(ctx.sessionTitle.get(session)?.title).toBe('Explain this referenced session')
+  })
+
+  it('waits through synthetic, empty, and non-text messages, then keeps the first fallback', async () => {
+    const ctx = new Context()
+    await ctx.plugin(SessionStore)
+    await ctx.plugin(SessionTitleService, CONFIG)
+    const session = ctx.sessions.create(SessionId('eligibility'))
+    session.append('turn/start', {
+      turn: 1,
+    })
+    session.append('user/message', createUserMessage({
+      content: [{ type: 'text', text: 'plugin text' }],
+      source: { kind: 'plugin', plugin: 'seed' },
+    }), { surfaceOp: 'append' })
+    session.append('user/message', createUserMessage({
+      content: [{ type: 'reasoning', text: 'not visible text' }],
+      source: { kind: 'user' },
+    }), { surfaceOp: 'append' })
+    session.append('user/message', createUserMessage({
+      content: [{ type: 'text', text: ' \n\t ' }],
+      source: { kind: 'user' },
+    }), { surfaceOp: 'append' })
+    await settleTitles()
+    expect(ctx.sessionTitle.get(session)).toBeUndefined()
+
+    const eligible = session.append('user/message', createUserMessage({
+      content: [{ type: 'text', text: 'first real prompt' }],
+      source: { kind: 'user' },
+    }), { surfaceOp: 'append' })
+    await settleTitles()
+    const first = ctx.sessionTitle.get(session)
+    session.append('user/message', createUserMessage({
+      content: [{ type: 'text', text: 'later prompt' }],
+      source: { kind: 'user' },
+    }), { surfaceOp: 'append' })
+    await settleTitles()
+
+    expect(first?.messageSeqs).toEqual([eligible.seq])
+    expect(ctx.sessionTitle.get(session)).toEqual(first)
+    expect(session.events.filter(event => event.type === 'session/title')).toHaveLength(1)
+  })
+
+  it('folds the latest title event during replay', () => {
+    const seed = Session.create(SessionId('source'))
+    seed.append('session/title', {
+      title: 'Earlier',
+      messageSeqs: [1],
+      source: { kind: 'fallback' },
+    })
+    seed.append('session/title', {
+      title: 'Later',
+      messageSeqs: [1, 4],
+      source: {
+        kind: 'provider',
+        provider: SessionTitleProviderId('test-provider'),
+        model: { provider: 'mock', model: 'title-model' },
+      },
+    })
+
+    expect(foldSessionTitle(seed.events)).toEqual({
+      title: 'Later',
+      messageSeqs: [1, 4],
+      source: {
+        kind: 'provider',
+        provider: SessionTitleProviderId('test-provider'),
+        model: { provider: 'mock', model: 'title-model' },
+      },
+      eventSeq: 1,
+      updatedAt: seed.events[1]?.time,
+    })
+  })
+})