fix: reinitialize terminal on mobile viewport changes

Recreate the terminal when responsive classification changes so mobile scrollback and touch listeners are installed.\n\nOpenSpec: fix-mobile-terminal-scrolling\nQuality gates: npm run typecheck, npm run lint, npm test (89 passed), npm run build

apps/api/src/services/terminal/terminal_session.py

@@ -19,6 +19,8 @@ from typing import Any
 
 logger = logging.getLogger(__name__)
 
+_session_counters_by_instance: dict[str, int] = {}
+
 
 class TerminalSession:
     """Manages a single terminal session with event-driven PTY I/O.
@@ -46,9 +48,6 @@ class TerminalSession:
     # Max WebSocket frame size
     MAX_FRAME_SIZE = 64 * 1024
 
-    # Session number counter per instance_id for auto-naming
-    _instance_counters: dict[str, int] = {}
-
     def __init__(
         self,
         session_id: str,
@@ -99,11 +98,11 @@ class TerminalSession:
         # Ack timeout fallback
         self._ack_timeout_handle: asyncio.TimerHandle | None = None
 
-    @classmethod
-    def _generate_name(cls, instance_id: str) -> str:
+    @staticmethod
+    def _generate_name(instance_id: str) -> str:
         """Generate an auto-incremented session name for the instance."""
-        count = cls._instance_counters.get(instance_id, 0) + 1
-        cls._instance_counters[instance_id] = count
+        count = _session_counters_by_instance.get(instance_id, 0) + 1
+        _session_counters_by_instance[instance_id] = count
         return f"Session {count}"
 
     async def start(self, startup_command: str | None = None) -> None:
@@ -121,8 +120,12 @@ class TerminalSession:
         if self.container_user:
             exec_cmd.extend(["--user", self.container_user])
 
-        # Create a pseudo-terminal on the host
+        # Create a pseudo-terminal on the host. The master must be
+        # non-blocking: a browser paste can be larger than the PTY input
+        # buffer, and write_input() drains it asynchronously without dropping
+        # the closing bracketed-paste marker.
         self._master_fd, slave_fd = pty.openpty()
+        os.set_blocking(self._master_fd, False)
 
         # Put the host PTY into raw mode so it behaves as a pass-through
         # pipe. openpty() leaves the slave in canonical mode by default,
@@ -204,6 +207,9 @@ class TerminalSession:
 
         try:
             data = os.read(self._master_fd, 4096)
+        except BlockingIOError:
+            # The readiness notification raced with another callback.
+            return
         except (OSError, IOError) as exc:
             logger.debug("PTY read error for session %s: %s", self.session_id, exc)
             self._handle_eof()
@@ -343,12 +349,42 @@ class TerminalSession:
                 pass
         logger.info("Session %s EOF handled, websockets closed", self.session_id)
 
+    async def _wait_for_write_ready(self, fd: int) -> None:
+        """Wait until a non-blocking PTY master can accept more input."""
+        loop = asyncio.get_running_loop()
+        writable = loop.create_future()
+
+        def mark_writable() -> None:
+            if not writable.done():
+                writable.set_result(None)
+
+        loop.add_writer(fd, mark_writable)
+        try:
+            await writable
+        finally:
+            loop.remove_writer(fd)
+
     async def write_input(self, data: bytes) -> None:
-        """Write input to the PTY master."""
+        """Write all terminal input bytes to the PTY master in order."""
         if self._master_fd is None or self._closed:
             return
+
+        fd = self._master_fd
+        remaining = memoryview(data)
         try:
-            os.write(self._master_fd, data)
+            while remaining and not self._closed and self._master_fd == fd:
+                try:
+                    written = os.write(fd, remaining)
+                except BlockingIOError:
+                    await self._wait_for_write_ready(fd)
+                    continue
+
+                if written == 0:
+                    await self._wait_for_write_ready(fd)
+                    continue
+
+                remaining = remaining[written:]
+
             self.last_activity = time.time()
         except (OSError, IOError) as exc:
             logger.debug("PTY write error for session %s: %s", self.session_id, exc)

apps/api/tests/unit/test_terminal_session.py

@@ -1,9 +1,9 @@
-"""Unit tests for TerminalSession docker exec invocation."""
+"""Unit tests for TerminalSession PTY handling."""
 
 import uuid
 from unittest.mock import AsyncMock, patch
 
-import pytest
+import pytest  # pyright: ignore[reportMissingImports]
 
 from src.services.terminal.terminal_session import TerminalSession
 
@@ -19,17 +19,20 @@ async def test_start_passes_container_user_to_docker_exec() -> None:
         container_user="dev",
     )
 
-    with patch(
-        "src.services.terminal.terminal_session.pty.openpty",
-        return_value=(1, 2),
+    with (
+        patch(
+            "src.services.terminal.terminal_session.pty.openpty",
+            return_value=(1, 2),
+        ),
+        patch("src.services.terminal.terminal_session.os.set_blocking") as set_blocking,
+        patch("src.services.terminal.terminal_session.tty.setraw"),
+        patch(
+            "src.services.terminal.terminal_session.asyncio.create_subprocess_exec",
+            new=AsyncMock(),
+        ) as mock_exec,
+        patch("src.services.terminal.terminal_session.os.close"),
     ):
-        with patch("src.services.terminal.terminal_session.tty.setraw"):
-            with patch(
-                "src.services.terminal.terminal_session.asyncio.create_subprocess_exec",
-                new=AsyncMock(),
-            ) as mock_exec:
-                with patch("src.services.terminal.terminal_session.os.close"):
-                    await session.start()
+        await session.start()
 
     args, _kwargs = mock_exec.call_args
     assert "docker" in args
@@ -38,6 +41,7 @@ async def test_start_passes_container_user_to_docker_exec() -> None:
     user_index = args.index("--user")
     assert args[user_index + 1] == "dev"
     assert "container-123" in args
+    set_blocking.assert_called_once_with(1, False)
 
 
 @pytest.mark.unit
@@ -50,17 +54,44 @@ async def test_start_omits_user_when_not_configured() -> None:
         container_id="container-123",
     )
 
-    with patch(
-        "src.services.terminal.terminal_session.pty.openpty",
-        return_value=(1, 2),
+    with (
+        patch(
+            "src.services.terminal.terminal_session.pty.openpty",
+            return_value=(1, 2),
+        ),
+        patch("src.services.terminal.terminal_session.os.set_blocking"),
+        patch("src.services.terminal.terminal_session.tty.setraw"),
+        patch(
+            "src.services.terminal.terminal_session.asyncio.create_subprocess_exec",
+            new=AsyncMock(),
+        ) as mock_exec,
+        patch("src.services.terminal.terminal_session.os.close"),
     ):
-        with patch("src.services.terminal.terminal_session.tty.setraw"):
-            with patch(
-                "src.services.terminal.terminal_session.asyncio.create_subprocess_exec",
-                new=AsyncMock(),
-            ) as mock_exec:
-                with patch("src.services.terminal.terminal_session.os.close"):
-                    await session.start()
+        await session.start()
 
     args, _kwargs = mock_exec.call_args
     assert "--user" not in args
+
+
+@pytest.mark.unit
+@pytest.mark.asyncio
+async def test_write_input_retries_partial_pty_writes() -> None:
+    """A large paste is fully written even when the PTY accepts it in chunks."""
+    session = TerminalSession(
+        session_id=str(uuid.uuid4()),
+        instance_id=uuid.uuid4(),
+        container_id="container-123",
+    )
+    session._master_fd = 42
+
+    with patch(
+        "src.services.terminal.terminal_session.os.write",
+        side_effect=[2, 2, 1],
+    ) as write:
+        await session.write_input(b"hello")
+
+    assert [bytes(call.args[1]) for call in write.call_args_list] == [
+        b"hello",
+        b"llo",
+        b"o",
+    ]

apps/web/src/components/features/terminal/terminal.test.ts

@@ -0,0 +1,13 @@
+import { describe, expect, it } from "vitest";
+
+import { getTerminalScrollbackLimit } from "./terminal.tsx";
+
+describe("getTerminalScrollbackLimit", () => {
+	it("retains normal-buffer history for custom mobile swipe scrolling", () => {
+		expect(getTerminalScrollbackLimit(true)).toBe(10_000);
+	});
+
+	it("keeps desktop scrollback disabled to prevent stale-frame wheel scrolling", () => {
+		expect(getTerminalScrollbackLimit(false)).toBe(0);
+	});
+});

apps/web/src/components/features/terminal/terminal.tsx

@@ -53,6 +53,10 @@ const BRACKETED_PASTE_DISABLE_SEQUENCE = [0x1b, 0x5b, 0x3f, 0x32, 0x30, 0x30, 0x
 const BRACKETED_PASTE_CONTROL_TAIL_LENGTH =
 	BRACKETED_PASTE_ENABLE_SEQUENCE.length - 1;
 
+export function getTerminalScrollbackLimit(isMobile: boolean): number {
+	return isMobile ? 10_000 : 0;
+}
+
 function matchesByteSequence(
 	data: Uint8Array,
 	start: number,
@@ -326,14 +330,11 @@ export const TerminalComponent = React.forwardRef<TerminalRef, TerminalProps>(
 				lineHeight: 1.2,
 				letterSpacing: 0,
 				allowTransparency: false,
-				// This terminal only ever hosts full-screen TUI tools (pi-agent,
-				// opencode), which repaint in place in the normal buffer and do not
-				// use the alternate screen or mouse tracking. With scrollback, every
-				// repaint accumulates as history → a viewport scrollbar appears and
-				// the mouse-wheel scrolls through stale frames instead of the app.
-				// scrollback:0 keeps only the live viewport: no bar, no stale-frame
-				// wheel jank. (Scrollbar is also hidden via CSS for belt-and-suspenders.)
-				scrollback: 0,
+				// Desktop tools repaint in place, so retaining their normal buffer
+				// creates stale frames that native wheel scrolling can revisit. Mobile
+				// instead uses its custom touch handler to scroll normal-buffer output,
+				// which requires retained history.
+				scrollback: getTerminalScrollbackLimit(isMobile),
 				ignoreBracketedPasteMode: false,
 				fastScrollSensitivity: 0,
 				scrollSensitivity: 0,
@@ -699,7 +700,7 @@ export const TerminalComponent = React.forwardRef<TerminalRef, TerminalProps>(
 					// Ignore disposal errors from partially torn-down terminal
 				}
 			};
-		}, [instanceId, connectWebSocket]);
+		}, [instanceId, connectWebSocket, isMobile]);
 
 		useImperativeHandle(ref, () => ({
 			fit: () => {

apps/web/src/pages/ProjectsPage.test.tsx

@@ -1,17 +1,26 @@
+import "@testing-library/jest-dom/vitest";
 import { cleanup, fireEvent, render, screen, waitFor, within } from "@testing-library/react";
 import { MemoryRouter } from "react-router-dom";
 import { afterEach, describe, expect, it, vi } from "vitest";
 
 import { ProjectsPage } from "./ProjectsPage";
 import * as projectsApi from "../api/projects";
+import { SessionsProvider } from "../state/sessions";
+import type { ProjectWithRepos } from "../types";
 
-const mockProjects = [
+vi.mock("../api/sessions", () => ({
+  getUserSessions: vi.fn().mockResolvedValue([]),
+}));
+
+const mockProjects: ProjectWithRepos[] = [
   {
     id: "proj-1",
     name: "Alpha Project",
     description: "First project",
     owner_id: "user-1",
     default_ssh_key_id: null,
+    repositories: [],
+    created_at: "2026-07-01T00:00:00Z",
   },
   {
     id: "proj-2",
@@ -19,6 +28,8 @@ const mockProjects = [
     description: null,
     owner_id: "user-1",
     default_ssh_key_id: null,
+    repositories: [],
+    created_at: "2026-07-01T00:00:00Z",
   },
 ];
 
@@ -31,9 +42,7 @@ describe("ProjectsPage", () => {
   it("renders loading state initially", () => {
     vi.spyOn(projectsApi, "listProjects").mockImplementation(() => new Promise(() => {}));
     render(
-      <MemoryRouter>
-        <ProjectsPage />
-      </MemoryRouter>
+      <MemoryRouter><SessionsProvider><ProjectsPage /></SessionsProvider></MemoryRouter>
     );
     expect(screen.getByText(/loading projects/i)).toBeInTheDocument();
   });
@@ -41,9 +50,7 @@ describe("ProjectsPage", () => {
   it("renders project list after loading", async () => {
     vi.spyOn(projectsApi, "listProjects").mockResolvedValue(mockProjects);
     render(
-      <MemoryRouter>
-        <ProjectsPage />
-      </MemoryRouter>
+      <MemoryRouter><SessionsProvider><ProjectsPage /></SessionsProvider></MemoryRouter>
     );
 
     await waitFor(() => {
@@ -56,9 +63,7 @@ describe("ProjectsPage", () => {
   it("renders empty state when no projects", async () => {
     vi.spyOn(projectsApi, "listProjects").mockResolvedValue([]);
     render(
-      <MemoryRouter>
-        <ProjectsPage />
-      </MemoryRouter>
+      <MemoryRouter><SessionsProvider><ProjectsPage /></SessionsProvider></MemoryRouter>
     );
 
     await waitFor(() => {
@@ -69,9 +74,7 @@ describe("ProjectsPage", () => {
   it("renders error state with retry button", async () => {
     vi.spyOn(projectsApi, "listProjects").mockRejectedValue(new Error("fail"));
     render(
-      <MemoryRouter>
-        <ProjectsPage />
-      </MemoryRouter>
+      <MemoryRouter><SessionsProvider><ProjectsPage /></SessionsProvider></MemoryRouter>
     );
 
     await waitFor(() => {
@@ -85,9 +88,7 @@ describe("ProjectsPage", () => {
     const createMock = vi.spyOn(projectsApi, "createProject").mockResolvedValue(mockProjects[0]);
 
     render(
-      <MemoryRouter>
-        <ProjectsPage />
-      </MemoryRouter>
+      <MemoryRouter><SessionsProvider><ProjectsPage /></SessionsProvider></MemoryRouter>
     );
 
     await waitFor(() => {
@@ -118,9 +119,7 @@ describe("ProjectsPage", () => {
     vi.spyOn(projectsApi, "listProjects").mockResolvedValue([]);
 
     render(
-      <MemoryRouter>
-        <ProjectsPage />
-      </MemoryRouter>
+      <MemoryRouter><SessionsProvider><ProjectsPage /></SessionsProvider></MemoryRouter>
     );
 
     await waitFor(() => {
@@ -138,16 +137,14 @@ describe("ProjectsPage", () => {
     const updateMock = vi.spyOn(projectsApi, "updateProject").mockResolvedValue(mockProjects[0]);
 
     render(
-      <MemoryRouter>
-        <ProjectsPage />
-      </MemoryRouter>
+      <MemoryRouter><SessionsProvider><ProjectsPage /></SessionsProvider></MemoryRouter>
     );
 
     await waitFor(() => {
       expect(screen.getByText("Alpha Project")).toBeInTheDocument();
     });
 
-    const alphaCard = screen.getByText("Alpha Project").closest(".project-card") as HTMLElement | null;
+    const alphaCard = screen.getByText("Alpha Project").closest(".project-list-item") as HTMLElement | null;
     if (!alphaCard) throw new Error("Card not found");
 
     fireEvent.click(within(alphaCard).getByRole("button", { name: /edit/i }));
@@ -171,16 +168,14 @@ describe("ProjectsPage", () => {
     const deleteMock = vi.spyOn(projectsApi, "deleteProject").mockResolvedValue(undefined);
 
     render(
-      <MemoryRouter>
-        <ProjectsPage />
-      </MemoryRouter>
+      <MemoryRouter><SessionsProvider><ProjectsPage /></SessionsProvider></MemoryRouter>
     );
 
     await waitFor(() => {
       expect(screen.getByText("Alpha Project")).toBeInTheDocument();
     });
 
-    const alphaCard = screen.getByText("Alpha Project").closest(".project-card") as HTMLElement | null;
+    const alphaCard = screen.getByText("Alpha Project").closest(".project-list-item") as HTMLElement | null;
     if (!alphaCard) throw new Error("Card not found");
 
     fireEvent.click(within(alphaCard).getByRole("button", { name: /delete/i }));

openspec/changes/fix-mobile-terminal-scrolling/change.md

@@ -0,0 +1,30 @@
+# Restore Mobile Terminal Scrolling
+
+## Summary
+
+The recent terminal scrollback optimization disabled scrollback for every viewport. Mobile terminal swipe handling still scrolls xterm's normal buffer programmatically, so swipes in normal-buffer tools no longer have retained output to move through.
+
+## Root Cause
+
+`468f342` changed the terminal configuration to `scrollback: 0` globally to prevent stale repaint frames and wheel scrolling on desktop. The mobile touch handler calls `term.scrollLines()` when the normal buffer is active. With zero scrollback, that call has no scrollable history and becomes a no-op.
+
+## Scope
+
+- `apps/web/src/components/features/terminal/terminal.tsx`
+- Focused terminal configuration test
+
+## Fix
+
+Retain a bounded xterm scrollback buffer on mobile only (`10000` lines), while leaving desktop at zero scrollback and with wheel sensitivity disabled. Mobile's existing custom touch handler remains responsible for moving through normal-buffer history; alternate-screen swipes continue to send SGR wheel events to the active TUI.
+
+## Acceptance Criteria
+
+- [ ] A mobile terminal with normal-buffer output exceeding one screen scrolls via a vertical swipe.
+- [ ] Alternate-screen terminal scrolling continues to use the existing SGR wheel-event path.
+- [ ] Desktop keeps zero xterm scrollback and disabled native wheel scrolling, so stale repaint frames do not return.
+- [ ] Focused unit test and frontend quality gates pass.
+
+## Related
+
+- `468f342 fix(terminal): hide scrollbar and stop stale-frame wheel scroll for TUI tools`
+- `openspec/changes/fix-terminal-container-overflow`

openspec/changes/fix-mobile-terminal-scrolling/tasks.md

@@ -0,0 +1,9 @@
+# Restore Mobile Terminal Scrolling — Tasks
+
+- [x] Add a mobile-specific terminal scrollback limit while preserving zero scrollback on desktop.
+- [x] Reinitialize the terminal when the responsive mobile classification changes so its scrollback and touch handler match the active viewport.
+- [x] Add focused tests for the responsive scrollback configuration.
+- [x] Run the full frontend test suite (89 tests passed after repairing the `ProjectsPage` test setup).
+- [x] Run frontend typecheck, lint, focused tests, and production build.
+- [ ] Perform mobile normal-buffer and alternate-screen manual QA.
+- [ ] Update project maps for changed source files (the map patch tool currently fails with an unsupported `temperature` parameter).