feat(v0.3): O2 — resume past Claude sessions

- src/http/history.ts: listSessions() reads ~/.claude/projects/*/*.jsonl
  (mtime-sorted, top 50), parseSessionMeta() extracts cwd + first user prompt
  (pure, 4 unit tests); GET /sessions
- terminal-session: opts.initialInput (typed ~700ms after the shell is ready)
- tabs.newTabForResume(cwd,id): new tab in the project dir running
  'claude --resume <id>'
- public/history.ts: 🕘 panel listing sessions (project · time · preview) with
  Resume buttons
- Verified: /sessions returns 44 real sessions; panel lists project/time/preview.
  216 tests green.

public/history.ts

@@ -0,0 +1,109 @@
+/**
+ * public/history.ts — resume a past Claude Code session (O2).
+ *
+ * A 🕘 toolbar button opens a list of past sessions (GET /sessions); clicking
+ * "Resume" opens a new tab in that project's directory and runs
+ * `claude --resume <id>`.
+ */
+
+export interface HistoryHooks {
+  resume: (cwd: string, id: string) => void
+}
+
+interface HistorySession {
+  id: string
+  cwd: string
+  project: string
+  mtimeMs: number
+  preview: string
+}
+
+function relTime(ms: number): string {
+  const s = Math.max(0, (Date.now() - ms) / 1000)
+  if (s < 60) return 'just now'
+  if (s < 3600) return `${Math.floor(s / 60)}m ago`
+  if (s < 86400) return `${Math.floor(s / 3600)}h ago`
+  return `${Math.floor(s / 86400)}d ago`
+}
+
+export function mountHistory(toolbar: HTMLElement, hooks: HistoryHooks): void {
+  const overlay = document.createElement('div')
+  overlay.id = 'historymodal'
+  overlay.style.display = 'none'
+  const card = document.createElement('div')
+  card.className = 'hist-card'
+  overlay.appendChild(card)
+  document.body.appendChild(overlay)
+
+  const hide = (): void => {
+    overlay.style.display = 'none'
+  }
+  overlay.addEventListener('click', (e) => {
+    if (e.target === overlay) hide()
+  })
+
+  const open = async (): Promise<void> => {
+    card.replaceChildren()
+    const title = document.createElement('div')
+    title.className = 'hist-title'
+    title.textContent = 'Resume a Claude session'
+    card.appendChild(title)
+    const status = document.createElement('div')
+    status.className = 'hist-empty'
+    status.textContent = 'Loading…'
+    card.appendChild(status)
+    overlay.style.display = 'flex'
+
+    let sessions: HistorySession[]
+    try {
+      const res = await fetch('/sessions')
+      sessions = (await res.json()) as HistorySession[]
+    } catch {
+      status.textContent = 'Failed to load sessions.'
+      return
+    }
+    if (sessions.length === 0) {
+      status.textContent = 'No past Claude sessions found.'
+      return
+    }
+    status.remove()
+
+    for (const s of sessions) {
+      const row = document.createElement('div')
+      row.className = 'hist-row'
+
+      const main = document.createElement('div')
+      main.className = 'hist-main'
+      const proj = document.createElement('div')
+      proj.className = 'hist-proj'
+      proj.textContent = `${s.project}  ·  ${relTime(s.mtimeMs)}`
+      const prev = document.createElement('div')
+      prev.className = 'hist-prev'
+      prev.textContent = s.preview || '(no preview)'
+      prev.title = s.cwd
+      main.append(proj, prev)
+
+      const btn = document.createElement('button')
+      btn.className = 'hist-resume'
+      btn.textContent = 'Resume'
+      btn.addEventListener('click', () => {
+        hooks.resume(s.cwd, s.id)
+        hide()
+      })
+
+      row.append(main, btn)
+      card.appendChild(row)
+    }
+  }
+
+  const toggle = document.createElement('button')
+  toggle.className = 'toolbtn'
+  toggle.textContent = '🕘'
+  toggle.title = 'Resume a past Claude session'
+  toggle.setAttribute('aria-label', 'Session history')
+  toggle.addEventListener('click', () => {
+    if (overlay.style.display === 'none') void open()
+    else hide()
+  })
+  toolbar.appendChild(toggle)
+}

public/main.ts

@@ -17,6 +17,7 @@ import { mountSearch } from './search.js'
 import { mountQrConnect } from './qr.js'
 import { mountSettings, loadSettings, type Settings } from './settings.js'
 import { mountDashboard } from './dashboard.js'
+import { mountHistory } from './history.js'
 
 const paneHost = document.getElementById('term')
 const tabs = document.getElementById('tabs')
@@ -51,6 +52,9 @@ mountDashboard(toolbar, {
   snapshot: () => app.snapshot(),
   focus: (idx) => app.focusTab(idx),
 })
+mountHistory(toolbar, {
+  resume: (cwd, id) => app.newTabForResume(cwd, id),
+})
 mountQrConnect(toolbar)
 
 // PWA: register the service worker (installable + offline shell, M4).

public/style.css

@@ -253,6 +253,73 @@ html, body {
   font-weight: 600;
 }
 
+/* History / resume modal (O2) */
+#historymodal {
+  position: fixed;
+  inset: 0;
+  z-index: 1200;
+  display: flex;
+  align-items: flex-start;
+  justify-content: center;
+  padding-top: 56px;
+  background: rgba(0, 0, 0, 0.6);
+}
+.hist-card {
+  background: #222;
+  border: 1px solid #3a3a3a;
+  border-radius: 10px;
+  min-width: 360px;
+  max-width: 92vw;
+  max-height: 72vh;
+  overflow-y: auto;
+  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.5);
+}
+.hist-title {
+  padding: 12px 16px;
+  font-weight: 600;
+  color: #fff;
+  border-bottom: 1px solid #3a3a3a;
+}
+.hist-empty {
+  padding: 16px;
+  color: #aaa;
+}
+.hist-row {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  padding: 10px 16px;
+  border-bottom: 1px solid #2a2a2a;
+}
+.hist-main {
+  flex: 1 1 auto;
+  min-width: 0;
+}
+.hist-proj {
+  color: #fff;
+  font-size: 13px;
+}
+.hist-prev {
+  color: #aaa;
+  font-size: 12px;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+}
+.hist-resume {
+  flex: none;
+  background: #2ea043;
+  color: #fff;
+  border: none;
+  border-radius: 5px;
+  padding: 6px 14px;
+  cursor: pointer;
+  font: inherit;
+}
+.hist-resume:hover {
+  background: #3fb950;
+}
+
 .tab {
   display: flex;
   align-items: center;

public/tabs.ts

@@ -151,7 +151,12 @@ export class TabApp {
 
   /* ── tab lifecycle ───────────────────────────────────────────── */
 
-  private addEntry(sessionId: string | null, customTitle: string | null, cwd?: string): TabEntry {
+  private addEntry(
+    sessionId: string | null,
+    customTitle: string | null,
+    cwd?: string,
+    initialInput?: string,
+  ): TabEntry {
     const entry: TabEntry = {
       session: null as unknown as TerminalSession,
       customTitle,
@@ -162,6 +167,7 @@ export class TabApp {
     entry.session = new TerminalSession({
       sessionId,
       ...(cwd !== undefined ? { cwd } : {}),
+      ...(initialInput !== undefined ? { initialInput } : {}),
       onSessionId: () => this.persist(),
       // onActivity only fires for hidden (inactive) panes (see TerminalSession).
       onActivity: () => {
@@ -198,6 +204,14 @@ export class TabApp {
     this.activate(this.tabs.length - 1)
   }
 
+  /** O2: open a new tab in `cwd` and run `claude --resume <id>`. */
+  newTabForResume(cwd: string, sessionId: string): void {
+    this.addEntry(null, null, cwd || undefined, `claude --resume ${sessionId}`)
+    this.persist()
+    this.rebuild()
+    this.activate(this.tabs.length - 1)
+  }
+
   activate(i: number): void {
     if (i < 0 || i >= this.tabs.length) return
     this.maybeAskNotify() // first switch is a user gesture — request notif permission

public/terminal-session.ts

@@ -54,6 +54,8 @@ export interface TerminalSessionOpts {
   onClaudeStatus?: (status: ClaudeStatus, detail?: string) => void
   /** Optional: spawn a NEW session in this directory ("new tab here", M6). */
   cwd?: string
+  /** Optional: type this once the new session's shell is ready (O2 resume). */
+  initialInput?: string
 }
 
 export class TerminalSession {
@@ -69,6 +71,8 @@ export class TerminalSession {
   private readonly onStatus: ((status: SessionStatus) => void) | undefined
   private readonly onClaudeStatus: ((status: ClaudeStatus, detail?: string) => void) | undefined
   private readonly spawnCwd: string | undefined
+  private readonly initialInput: string | undefined
+  private initialSent = false
   private statusValue: SessionStatus = 'connecting'
   private claudeStatusValue: ClaudeStatus = 'unknown'
   private cwdValue: string | null = null
@@ -94,6 +98,7 @@ export class TerminalSession {
     this.onStatus = opts.onStatus
     this.onClaudeStatus = opts.onClaudeStatus
     this.spawnCwd = opts.cwd
+    this.initialInput = opts.initialInput
 
     this.el = document.createElement('div')
     this.el.className = 'term-pane'
@@ -238,6 +243,12 @@ export class TerminalSession {
         this.onSessionId(msg.sessionId)
         const dims = this.safefit()
         if (dims !== null) this.sendResize(dims.cols, dims.rows)
+        // O2: once the shell is up, type the resume command (only on first attach).
+        if (this.initialInput !== undefined && !this.initialSent) {
+          this.initialSent = true
+          const cmd = this.initialInput
+          setTimeout(() => this.send(cmd), 700)
+        }
         break
       }
       case 'output': {