feat(v0.3): M6 — new tab opens in the active tab's directory

- title-util.cwdFromOsc7: parse cwd from OSC 7 (file:// URL); 4 unit tests
- terminal-session: register OSC 7 handler → cwd getter; opts.cwd → sent in the
  attach frame on a fresh session
- protocol/types: ClientMessage attach.cwd (absolute path); validated
- session/manager/server: thread cwd → createSession spawn cwd (defaults homeDir)
- tabs: '+' (newTab) opens in the active tab's reported cwd, falls back to home
- Verified: server attach.cwd spawns there; cd /private/tmp → + → new tab pwd is
  /private/tmp. 212 tests green.

public/tabs.ts

@@ -151,7 +151,7 @@ export class TabApp {
 
   /* ── tab lifecycle ───────────────────────────────────────────── */
 
-  private addEntry(sessionId: string | null, customTitle: string | null): TabEntry {
+  private addEntry(sessionId: string | null, customTitle: string | null, cwd?: string): TabEntry {
     const entry: TabEntry = {
       session: null as unknown as TerminalSession,
       customTitle,
@@ -161,6 +161,7 @@ export class TabApp {
     }
     entry.session = new TerminalSession({
       sessionId,
+      ...(cwd !== undefined ? { cwd } : {}),
       onSessionId: () => this.persist(),
       // onActivity only fires for hidden (inactive) panes (see TerminalSession).
       onActivity: () => {
@@ -189,7 +190,9 @@ export class TabApp {
   }
 
   newTab(): void {
-    this.addEntry(null, null)
+    // M6: open the new tab in the active tab's current directory, if known.
+    const cwd = this.tabs[this.activeIndex]?.session.cwd ?? undefined
+    this.addEntry(null, null, cwd)
     this.persist()
     this.rebuild()
     this.activate(this.tabs.length - 1)

public/terminal-session.ts

@@ -14,7 +14,7 @@ import { FitAddon } from '@xterm/addon-fit'
 import { SearchAddon } from '@xterm/addon-search'
 import { WebLinksAddon } from '@xterm/addon-web-links'
 import type { ClaudeStatus, ClientMessage, ServerMessage } from '../src/types.js'
-import { folderFromTitle } from './title-util.js'
+import { folderFromTitle, cwdFromOsc7 } from './title-util.js'
 
 const RESET = '\x1b[0m'
 const BOLD = '\x1b[1m'
@@ -54,6 +54,8 @@ export interface TerminalSessionOpts {
   onStatus?: (status: SessionStatus) => void
   /** Optional: fired when Claude Code activity changes (from a hook, H2). */
   onClaudeStatus?: (status: ClaudeStatus, detail?: string) => void
+  /** Optional: spawn a NEW session in this directory ("new tab here", M6). */
+  cwd?: string
 }
 
 export class TerminalSession {
@@ -68,8 +70,10 @@ export class TerminalSession {
   private readonly onTitle: ((title: string) => void) | undefined
   private readonly onStatus: ((status: SessionStatus) => void) | undefined
   private readonly onClaudeStatus: ((status: ClaudeStatus, detail?: string) => void) | undefined
+  private readonly spawnCwd: string | undefined
   private statusValue: SessionStatus = 'connecting'
   private claudeStatusValue: ClaudeStatus = 'unknown'
+  private cwdValue: string | null = null
   private pendingApprovalValue = false
   private pendingToolValue: string | undefined = undefined
 
@@ -91,6 +95,7 @@ export class TerminalSession {
     this.onTitle = opts.onTitle
     this.onStatus = opts.onStatus
     this.onClaudeStatus = opts.onClaudeStatus
+    this.spawnCwd = opts.cwd
 
     this.el = document.createElement('div')
     this.el.className = 'term-pane'
@@ -111,6 +116,12 @@ export class TerminalSession {
     this.term.onData((data) => this.send(data))
     // Tab title = current folder, derived from the shell's OSC title.
     this.term.onTitleChange((title) => this.onTitle?.(folderFromTitle(title) ?? title))
+    // OSC 7 reports the full cwd (M6) — used for "new tab here".
+    this.term.parser.registerOscHandler(7, (payload) => {
+      const c = cwdFromOsc7(payload)
+      if (c !== null) this.cwdValue = c
+      return true
+    })
 
     this.resizeObserver = new ResizeObserver(() => this.scheduleResize())
     this.resizeObserver.observe(this.el)
@@ -131,6 +142,11 @@ export class TerminalSession {
     return this.claudeStatusValue
   }
 
+  /** Current working directory reported by the shell via OSC 7 (M6), or null. */
+  get cwd(): string | null {
+    return this.cwdValue
+  }
+
   /** Whether a tool approval is held server-side and can be resolved (H3). */
   get pendingApproval(): boolean {
     return this.pendingApprovalValue
@@ -189,7 +205,13 @@ export class TerminalSession {
       this.reconnectDelay = 1000
       this.setStatus('connected')
       this.term.write(statusLine(`${GREEN}${BOLD}Connected${RESET}`))
-      socket.send(buildMessage({ type: 'attach', sessionId: this.sessionId }))
+      // Send cwd only on a fresh session (M6 "new tab here"); on reconnect the
+      // sessionId is already set and the server ignores cwd.
+      const attachMsg: ClientMessage =
+        this.sessionId === null && this.spawnCwd !== undefined
+          ? { type: 'attach', sessionId: null, cwd: this.spawnCwd }
+          : { type: 'attach', sessionId: this.sessionId }
+      socket.send(buildMessage(attachMsg))
     })
 
     socket.addEventListener('message', (event: MessageEvent<string>) => {

public/title-util.ts

@@ -23,3 +23,19 @@ export function folderFromTitle(title: string): string | null {
   if (slash !== -1) s = s.slice(slash + 1)
   return s || null
 }
+
+/**
+ * Parse the full cwd path from an OSC 7 sequence payload (M6).
+ *   data = "file://host/Users/me/dir"  →  "/Users/me/dir"
+ * Returns null if it isn't a file:// URL.
+ */
+export function cwdFromOsc7(data: string): string | null {
+  const m = /^file:\/\/[^/]*(\/.*)$/.exec(data.trim())
+  if (m === null) return null
+  const path = m[1] as string
+  try {
+    return decodeURIComponent(path)
+  } catch {
+    return path
+  }
+}

src/protocol.ts

@@ -133,8 +133,21 @@ function validateAttach(obj: Record<string, unknown>): ParseResult {
     return { ok: false, error: 'attach.sessionId field is required' }
   }
 
+  // Optional cwd (M6): must be an absolute path string if present.
+  const rawCwd = obj['cwd']
+  let cwd: string | undefined
+  if (rawCwd !== undefined) {
+    if (typeof rawCwd !== 'string' || !rawCwd.startsWith('/')) {
+      return { ok: false, error: 'attach.cwd must be an absolute path string' }
+    }
+    cwd = rawCwd
+  }
+
   if (sessionId === null) {
-    return { ok: true, message: { type: 'attach', sessionId: null } }
+    return {
+      ok: true,
+      message: cwd !== undefined ? { type: 'attach', sessionId: null, cwd } : { type: 'attach', sessionId: null },
+    }
   }
 
   if (typeof sessionId !== 'string') {
@@ -151,7 +164,10 @@ function validateAttach(obj: Record<string, unknown>): ParseResult {
     }
   }
 
-  return { ok: true, message: { type: 'attach', sessionId } }
+  return {
+    ok: true,
+    message: cwd !== undefined ? { type: 'attach', sessionId, cwd } : { type: 'attach', sessionId },
+  }
 }
 
 // ─── serialize ────────────────────────────────────────────────────────────────

src/server.ts

@@ -229,7 +229,7 @@ export function startServer(cfg: Config): { close(): Promise<void> } {
 
         let session
         try {
-          session = manager.handleAttach(ws, msg.sessionId, dims, Date.now())
+          session = manager.handleAttach(ws, msg.sessionId, dims, Date.now(), msg.cwd)
         } catch (err: unknown) {
           // M4: spawn failure — send exit(-1) and close only this connection.
           const reason =

src/session/manager.ts

@@ -82,11 +82,13 @@ export function createSessionManager(cfg: Config): SessionManager {
     sessionId: string | null,
     dims: Dims,
     now: number,
+    cwd?: string,
   ): Session {
     // ── Case 1: null → always create a new session ──────────────────────────
     if (sessionId === null) {
       // M4: createSession may throw (spawn failure). Do NOT catch here.
-      const session = createSession(cfg, dims, now, onSessionExit);
+      // M6: cwd (if given) is the spawn directory for "new tab here".
+      const session = createSession(cfg, dims, now, onSessionExit, undefined, cwd);
       const kicked = attachWs(session, ws);
       if (kicked !== null) kicked.close();
       sessions = new Map(sessions).set(session.meta.id, session);

src/session/session.ts

@@ -61,6 +61,8 @@ export function createSession(
   // H1: pass an existing id to RE-ATTACH to a surviving tmux session (e.g. after
   // a server restart). Default = a fresh id for a brand-new session.
   id: string = randomUUID(),
+  // M6: spawn directory for a new session ("new tab here"); defaults to homeDir.
+  cwd?: string,
 ): Session {
   // The id is injected into the shell env so Claude Code hooks know which tab an
   // event belongs to ($WEBTERM_SESSION) and where to POST ($WEBTERM_HOOK_URL, H2).
@@ -76,7 +78,7 @@ export function createSession(
     name: 'xterm-256color',
     cols: dims.cols,
     rows: dims.rows,
-    cwd: cfg.homeDir,
+    cwd: cwd ?? cfg.homeDir,
     env: {
       ...process.env,
       WEBTERM_SESSION: id,

src/types.ts

@@ -39,9 +39,10 @@ export type EnvLike = Readonly<Record<string, string | undefined>>;
 
 /* ─────────────────────── protocol (§3.2) ─────────────────────── */
 
-/** client → server. approve/reject (H3) resolve a held PermissionRequest. */
+/** client → server. approve/reject (H3) resolve a held PermissionRequest.
+ *  attach.cwd (M6) = spawn a new session in this directory ("new tab here"). */
 export type ClientMessage =
-  | { type: 'attach'; sessionId: string | null }
+  | { type: 'attach'; sessionId: string | null; cwd?: string }
   | { type: 'input'; data: string }
   | { type: 'resize'; cols: number; rows: number }
   | { type: 'approve' }
@@ -167,7 +168,13 @@ export interface Session {
 /* ──────────────────────── manager (§3.5) ─────────────────────── */
 
 export interface SessionManager {
-  handleAttach(ws: WebSocketLike, sessionId: string | null, dims: Dims, now: number): Session;
+  handleAttach(
+    ws: WebSocketLike,
+    sessionId: string | null,
+    dims: Dims,
+    now: number,
+    cwd?: string,
+  ): Session;
   get(id: string): Session | undefined;
   /** Set a session's Claude status (from a hook) and push it to the attached ws (H2/H3). */
   handleHookEvent(

test/title-util.test.ts

@@ -1,5 +1,21 @@
 import { describe, it, expect } from 'vitest'
-import { folderFromTitle } from '../public/title-util.js'
+import { folderFromTitle, cwdFromOsc7 } from '../public/title-util.js'
+
+describe('cwdFromOsc7', () => {
+  it('extracts the path from a file:// URL with a host', () => {
+    expect(cwdFromOsc7('file://mac.local/Users/me/web-terminal')).toBe('/Users/me/web-terminal')
+  })
+  it('extracts the path with an empty host (file:///)', () => {
+    expect(cwdFromOsc7('file:///Users/me/dir')).toBe('/Users/me/dir')
+  })
+  it('decodes percent-encoded spaces', () => {
+    expect(cwdFromOsc7('file://h/Users/me/my%20dir')).toBe('/Users/me/my dir')
+  })
+  it('returns null for non-file URLs', () => {
+    expect(cwdFromOsc7('http://x/y')).toBeNull()
+    expect(cwdFromOsc7('garbage')).toBeNull()
+  })
+})
 
 describe('folderFromTitle', () => {
   it('extracts the folder from user@host:~/path', () => {