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.

src/http/history.ts

@@ -0,0 +1,121 @@
+/**
+ * src/http/history.ts (O2) — list past Claude Code sessions for the resume browser.
+ *
+ * Reads ~/.claude/projects/<encoded>/<session-uuid>.jsonl. Each session's first
+ * user message is the preview and its `cwd` is the project directory (so resume
+ * can `claude --resume <id>` in the right place). Read-only; best-effort.
+ */
+
+import fs from 'node:fs';
+import os from 'node:os';
+import path from 'node:path';
+
+export interface HistorySession {
+  id: string;
+  cwd: string;
+  project: string; // last path segment, for display
+  mtimeMs: number;
+  preview: string;
+}
+
+/** Extract cwd + the first real user prompt from a session jsonl (pure, testable). */
+export function parseSessionMeta(jsonlText: string): { cwd: string | null; preview: string } {
+  let cwd: string | null = null;
+  let preview = '';
+
+  for (const line of jsonlText.split('\n')) {
+    const trimmed = line.trim();
+    if (trimmed === '') continue;
+    let obj: Record<string, unknown>;
+    try {
+      obj = JSON.parse(trimmed) as Record<string, unknown>;
+    } catch {
+      continue;
+    }
+
+    if (cwd === null && typeof obj['cwd'] === 'string') cwd = obj['cwd'];
+
+    if (preview === '' && obj['type'] === 'user') {
+      const msg = obj['message'];
+      if (msg !== null && typeof msg === 'object') {
+        const content = (msg as Record<string, unknown>)['content'];
+        if (typeof content === 'string') {
+          preview = content;
+        } else if (Array.isArray(content)) {
+          for (const part of content) {
+            if (part !== null && typeof part === 'object') {
+              const p = part as Record<string, unknown>;
+              if (p['type'] === 'text' && typeof p['text'] === 'string') {
+                preview = p['text'];
+                break;
+              }
+            }
+          }
+        }
+      }
+    }
+
+    if (cwd !== null && preview !== '') break;
+  }
+
+  return { cwd, preview: preview.replace(/\s+/g, ' ').trim().slice(0, 120) };
+}
+
+function readHead(file: string, max: number): string {
+  try {
+    const fd = fs.openSync(file, 'r');
+    try {
+      const buf = Buffer.alloc(max);
+      const n = fs.readSync(fd, buf, 0, max, 0);
+      return buf.subarray(0, n).toString('utf8');
+    } finally {
+      fs.closeSync(fd);
+    }
+  } catch {
+    return '';
+  }
+}
+
+/** Most-recently-modified Claude Code sessions across all projects. */
+export function listSessions(limit = 50): HistorySession[] {
+  const root = path.join(os.homedir(), '.claude', 'projects');
+  let dirs: string[];
+  try {
+    dirs = fs.readdirSync(root);
+  } catch {
+    return [];
+  }
+
+  const files: Array<{ id: string; file: string; mtimeMs: number }> = [];
+  for (const dir of dirs) {
+    const dirPath = path.join(root, dir);
+    let names: string[];
+    try {
+      names = fs.readdirSync(dirPath);
+    } catch {
+      continue;
+    }
+    for (const name of names) {
+      if (!name.endsWith('.jsonl')) continue;
+      try {
+        const st = fs.statSync(path.join(dirPath, name));
+        files.push({
+          id: name.slice(0, -'.jsonl'.length),
+          file: path.join(dirPath, name),
+          mtimeMs: st.mtimeMs,
+        });
+      } catch {
+        // skip unreadable
+      }
+    }
+  }
+
+  files.sort((a, b) => b.mtimeMs - a.mtimeMs);
+
+  return files.slice(0, limit).map((f) => {
+    const meta = parseSessionMeta(readHead(f.file, 256 * 1024));
+    const cwd = meta.cwd ?? '';
+    const project = cwd !== '' ? (cwd.split('/').filter(Boolean).pop() ?? cwd) : 'unknown';
+    return { id: f.id, cwd, project, mtimeMs: f.mtimeMs, preview: meta.preview };
+  });
+}