fix: force interactive login shell for bash containers

Detached containers with tty: true still exited immediately because a
plain /bin/bash invocation exits with code 0 when stdin is not connected.

- Detect when the container CMD is /bin/bash or bash and exec an
  interactive login shell () after dropping privileges
- Keep the generic  path for non-shell commands
- Bump compiler_version to v4 to force a fresh image build

Quality gates:
- pytest tests/unit: 219 passed
- ruff: clean on changed files
- mypy: clean on changed files

apps/api/.pi-map.index.md

@@ -2,7 +2,7 @@
 dir: apps/api
 
 ## role
-FastAPI backend API that manages projects, git repositories, and development tools through Docker-based instances with PostgreSQL persistence.
+Self-hosted FastAPI backend API that manages projects, git repositories, and development tools by orchestrating Docker instances for remote development environments.
 ## parent
 index: apps/.pi-map.index.md
 map: apps/.pi-map.md

apps/api/.pi-map.md

@@ -4,7 +4,7 @@ dir: apps/api
 index: apps/api/.pi-map.index.md
 
 ## role
-FastAPI backend API that manages projects, git repositories, and development tools through Docker-based instances with PostgreSQL persistence.
+Self-hosted FastAPI backend API that manages projects, git repositories, and development tools by orchestrating Docker instances for remote development environments.
 ## files
 - .dockerignore | Specifies files and directories to exclude from Docker build context to reduce image size and avoid copying unnecessary files into containers. | dep: Docker
 - Dockerfile | Multi-stage Docker build for a Python application with Docker socket access, Cloudflare tunneling, and database dependency waiting | dep: python:3.11-slim, gcc, libpq-dev, docker-ce-cli, docker-compose-plugin, cloudflared, uvicorn, pyproject.toml dependencies
@@ -14,7 +14,7 @@ FastAPI backend API that manages projects, git repositories, and development too
 - uv.lock | Lock file for the uv Python package manager that pins exact dependency versions and their artifact hashes for reproducible installations | dep: uv, Python 3.11+, aiosqlite, alembic, annotated-doc, annotated-types, anyio, ast-serialize, asyncpg, and many other PyPI packages
 - wait-for-db.sh | Wait for a PostgreSQL database to become available before executing a command, with configurable retry logic. | dep: nc (netcat), sh (POSIX shell), sleep
 ## arch
-Async Python/FastAPI service using multi-stage Docker containers, Alembic migrations, uv package management, and external Docker socket access for container orchestration.
+Async Python backend using FastAPI with PostgreSQL (asyncpg), Alembic migrations, uv package management, multi-stage Docker builds with Docker-in-Docker socket access, and Cloudflare tunneling for secure external connectivity.
 ## tags
 docker, alembic, python, database, fastapi, postgresql, asyncpg, uvicorn
 ## symbols

apps/api/src/services/build/manifest_compiler.py

@@ -393,6 +393,13 @@ def compile_entrypoint(manifest: dict) -> str:
     if user:
         name = user["name"]
         lines.append("# Drop privileges to the container user")
+        # When the container command is a shell, force an interactive login
+        # shell. Detached containers may not have stdin connected, and a plain
+        # /bin/bash invocation exits immediately with code 0. -il keeps it
+        # alive so the container stays running for docker exec/web terminals.
+        lines.append('if [ "$1" = "/bin/bash" ] || [ "$1" = "bash" ]; then')
+        lines.append(f'    exec runuser -u {name} -- /bin/bash -il')
+        lines.append('fi')
         lines.append(f'exec runuser -u {name} -- "$@"')
     else:
         lines.append('exec "$@"')
@@ -582,7 +589,7 @@ def compute_image_tag(tool_name: str, manifest: dict) -> str:
     Returns:
         Docker image tag string.
     """
-    compiler_version = "v3"  # bump when compile_dockerfile/entrypoint/compose change
+    compiler_version = "v4"  # bump when compile_dockerfile/entrypoint/compose change
     canonical = json.dumps(manifest, sort_keys=True, separators=(",", ":"))
     hash_suffix = hashlib.sha256(
         f"{compiler_version}:{canonical}".encode()

apps/api/tests/.pi-map.index.md

@@ -2,7 +2,7 @@
 dir: apps/api/tests
 
 ## role
-Provides shared test infrastructure and fixtures for API integration testing
+Provides shared test infrastructure and fixtures for the API application's test suite.
 ## parent
 index: apps/api/.pi-map.index.md
 map: apps/api/.pi-map.md

apps/api/tests/.pi-map.md

@@ -4,11 +4,11 @@ dir: apps/api/tests
 index: apps/api/tests/.pi-map.index.md
 
 ## role
-Provides shared test infrastructure and fixtures for API integration testing
+Provides shared test infrastructure and fixtures for the API application's test suite.
 ## files
 - conftest.py | Provides shared pytest fixtures for testing a FastAPI application with async SQLite database, authenticated clients, and test data setup. | exp: func:test_client() → Generator[TestClient, None, None], call:create_async_engine, call:engine.begin, call:conn.run_sync, call:asyncio.run, call:init_db, call:async_sessionmaker, call:patch, call:TestClient, call:app.dependency_overrides.pop, call:engine.dispose, func:init_db(), call:engine.begin, call:conn.run_sync, func:override_get_db_session() → AsyncGenerator[AsyncSession, None], call:async_sessionmaker, func:db_session(test_client) → AsyncGenerator[AsyncSession, None], call:app.dependency_overrides.get, call:override_fn, call:gen.asend, call:gen.aclose, call:create_async_engine, call:engine.begin, call:conn.run_sync, call:async_sessionmaker, call:engine.dispose, func:authenticated_client(test_client) → Generator[TestClient, None, None], call:str, call:uuid.uuid4, call:Settings, call:app.dependency_overrides.get, call:override_fn, call:gen.asend, call:User, call:uuid.UUID, call:session.add, call:session.commit, call:gen.aclose, call:asyncio.run, call:create_test_user, call:create_session_cookie, call:test_client.cookies.set, func:create_test_user(), call:app.dependency_overrides.get, call:override_fn, call:gen.asend, call:User, call:uuid.UUID, call:session.add, call:session.commit, call:gen.aclose, func:test_project_and_repo(authenticated_client) → tuple[str, str], call:uuid.uuid4, call:Settings, call:authenticated_client.cookies.get, call:decode_session_cookie, call:uuid.UUID, call:asyncio.run, call:get_user_id, call:app.dependency_overrides.get, call:override_fn, call:gen.asend, call:Project, call:session.add, call:GitRepository, call:session.commit, call:gen.aclose, call:create_project_and_repo, call:str, raise:RuntimeError, func:get_user_id(), call:Settings, call:authenticated_client.cookies.get, call:decode_session_cookie, call:uuid.UUID, func:create_project_and_repo(), call:app.dependency_overrides.get, call:override_fn, call:gen.asend, call:Project, call:session.add, call:GitRepository, call:session.commit, call:gen.aclose, func:admin_client(test_client) → Generator[TestClient, None, None], call:str, call:uuid.uuid4, call:Settings, call:app.dependency_overrides.get, call:override_fn, call:gen.asend, call:User, call:uuid.UUID, call:session.add, call:session.commit, call:gen.aclose, call:asyncio.run, call:create_admin_user, call:create_session_cookie, call:test_client.cookies.set, func:create_admin_user(), call:app.dependency_overrides.get, call:override_fn, call:gen.asend, call:User, call:uuid.UUID, call:session.add, call:session.commit, call:gen.aclose | dep: asyncio, os, typing, unittest.mock, pytest, pytest_asyncio, fastapi.testclient, sqlalchemy.ext.asyncio, src.config, src.models.base, src.main, src.auth.dependencies, uuid, src.auth.session, src.models.user.user, src.models.project.project, src.models.project.git_repository, fastapi, sqlalchemy, aiosqlite, src.models, src.auth
 ## arch
-Pytest fixture-based architecture with async SQLite test database, dependency injection overrides, and authenticated client factories for FastAPI endpoint testing
+Pytest fixture-based testing architecture with async SQLite test database, dependency injection overrides, and authenticated client factories using FastAPI's TestClient.
 ## tags
 call:app.dependency, call:create, overrides.get, call:override, fn, call:gen.asend, call:gen.aclose, user
 ## symbols

apps/api/tests/unit/.pi-map.index.md

@@ -2,7 +2,7 @@
 dir: apps/api/tests/unit
 
 ## role
-Contains comprehensive unit tests for the API application's core services, utilities, and infrastructure components.
+Contains unit tests for the API application's core services, utilities, and infrastructure components.
 ## parent
 index: apps/api/tests/.pi-map.index.md
 map: apps/api/tests/.pi-map.md

apps/api/tests/unit/.pi-map.md

@@ -4,7 +4,7 @@ dir: apps/api/tests/unit
 index: apps/api/tests/unit/.pi-map.index.md
 
 ## role
-Contains comprehensive unit tests for the API application's core services, utilities, and infrastructure components.
+Contains unit tests for the API application's core services, utilities, and infrastructure components.
 ## files
 - __init__.py | Empty file with no functionality
 - test_alembic_migrations.py | Unit tests that verify Alembic database migrations are importable, have correct revision identifiers, and declare expected dependencies without requiring a live database. | exp: func:test_home_directory_migration_imports_and_rewrites() → None, call:Path, call:migration_path.exists, call:importlib.util.spec_from_file_location, call:importlib.util.module_from_spec, call:spec.loader.exec_module, call:callable, func:test_merge_migration_resolves_heads() → None, call:Path, call:migration_path.exists, call:importlib.util.spec_from_file_location, call:importlib.util.module_from_spec, call:spec.loader.exec_module, call:callable, func:test_remove_pi_agent_repo_mount_migration_imports() → None, call:Path, call:migration_path.exists, call:importlib.util.spec_from_file_location, call:importlib.util.module_from_spec, call:spec.loader.exec_module, call:callable | dep: importlib.util, pathlib, pytest, importlib
@@ -30,7 +30,7 @@ Contains comprehensive unit tests for the API application's core services, utili
 - test_readiness_probe.py | Unit tests for a Docker container readiness probe service that executes commands via docker exec with retry logic. | exp: class:TestExecuteProbe, class:TestIntegrationScenarios | dep: unittest.mock, src.services.shared.readiness_probe, subprocess
 - test_ssh_keys.py | Unit tests for SSH key preparation functionality including file creation, permissions, ownership, and error handling | exp: class:TestPrepareSshKeyFiles | dep: os, pathlib, unittest.mock, pytest, src.services.shared.ssh_keys
 ## arch
-Standard Python unittest/pytest pattern with heavy use of mocking (subprocess, filesystem, database) to isolate components; tests are organized by service/domain with each file targeting a single module/class; no internal dependencies between test files.
+Comprehensive unit test suite using mocked dependencies to test business logic in isolation, covering database migrations, configuration, Docker operations, Git workflows, file services, event handling, health monitoring, and SSH/security utilities.
 ## tags
 test, url, call:notification, git, call:, home, merge, call:db
 ## symbols

apps/api/tests/unit/test_manifest_compiler.py

@@ -270,6 +270,7 @@ def test_compile_dockerfile_starts_as_root_and_drops_privileges() -> None:
     entrypoint = compile_entrypoint(manifest)
 
     assert "USER dev" not in dockerfile
+    assert 'exec runuser -u dev -- /bin/bash -il' in entrypoint
     assert 'exec runuser -u dev -- "$@"' in entrypoint