fix: make container media diagnostics reliable

Dockerfile

@@ -1,7 +1,10 @@
 ARG M4B_TOOL_IMAGE=sandreas/m4b-tool:0.5.2
 FROM ${M4B_TOOL_IMAGE}
 
-RUN apk add --no-cache python3 py3-pip
+# Alpine's ffmpeg package supplies ffprobe. /usr/local/bin/ffmpeg from the
+# upstream image remains first on PATH for its specialized codec build.
+RUN apk add --no-cache ffmpeg python3 py3-pip \
+    && ffprobe -version
 
 WORKDIR /app
 COPY pyproject.toml /app/

app/main.py

@@ -18,6 +18,11 @@ from .tui import AudiobookApp, TerminalUI
 
 _DEFAULT_CONFIG = Path("config.toml")
 _EXECUTABLES = ("m4b-tool", "ffmpeg", "ffprobe")
+_VERSION_ARGUMENTS = {
+    "m4b-tool": ("--version",),
+    "ffmpeg": ("-version",),
+    "ffprobe": ("-version",),
+}
 
 
 def _parser() -> argparse.ArgumentParser:
@@ -43,7 +48,11 @@ def _version(executable: str) -> str | None:
         return None
     try:
         result = subprocess.run(
-            (executable, "--version"), text=True, capture_output=True, check=False, timeout=5
+            (executable, *_VERSION_ARGUMENTS[executable]),
+            text=True,
+            capture_output=True,
+            check=False,
+            timeout=5,
         )
     except (OSError, subprocess.TimeoutExpired):
         return None

scripts/container-smoke.sh

@@ -2,6 +2,9 @@
 set -eu
 
 m4b-tool --version
+ffmpeg -version
+ffprobe -version
+
 merge_help=$(m4b-tool merge --help 2>&1)
 for required_option in \
     --jobs \
@@ -26,8 +29,6 @@ done
 if [ "${AUDIOBOOK_SMOKE_OPTION_GUARD_ONLY:-0}" = 1 ]; then
     exit 0
 fi
-ffmpeg -version
-ffprobe -version
 
 smoke_root=$(mktemp -d "${TMPDIR:-/tmp}/audiobook-tui-smoke.XXXXXX")
 trap 'rm -rf "$smoke_root"' EXIT HUP INT TERM

tests/test_main.py

@@ -1,6 +1,8 @@
 from io import StringIO
 from pathlib import Path
 
+import pytest
+
 import app.main as main_module
 from app.models import Roots, Settings
 
@@ -20,6 +22,33 @@ def test_doctor_is_read_only_and_reports_missing_config(tmp_path: Path, capsys)
     assert "configuration" in capsys.readouterr().out.lower()
 
 
+@pytest.mark.parametrize(
+    ("executable", "expected_argument"),
+    (("m4b-tool", "--version"), ("ffmpeg", "-version"), ("ffprobe", "-version")),
+)
+def test_version_uses_each_executables_supported_version_argument(
+    tmp_path: Path,
+    monkeypatch: pytest.MonkeyPatch,
+    executable: str,
+    expected_argument: str,
+) -> None:
+    binary_directory = tmp_path / "bin"
+    binary_directory.mkdir()
+    fake = binary_directory / executable
+    fake.write_text(
+        "#!/bin/sh\n"
+        f'if [ "$#" -ne 1 ] || [ "$1" != "{expected_argument}" ]; then\n'
+        "  exit 64\n"
+        "fi\n"
+        f"printf '%s\\n' '{executable} expected version'\n",
+        encoding="utf-8",
+    )
+    fake.chmod(0o755)
+    monkeypatch.setenv("PATH", str(binary_directory))
+
+    assert main_module._version(executable) == f"{executable} expected version"
+
+
 def test_doctor_checks_an_existing_destination_root_not_just_its_parent(tmp_path: Path) -> None:
     pending = tmp_path / "pending"
     pending.mkdir()

tests/test_packaging.py

@@ -27,6 +27,27 @@ def _service() -> dict[str, object]:
     return compose["services"]["audiobook-tui"]
 
 
+def _write_fake_media_versions(
+    binary_directory: Path, *, ffprobe_available: bool = True
+) -> None:
+    for executable in ("ffmpeg", "ffprobe"):
+        fake = binary_directory / executable
+        if executable == "ffprobe" and not ffprobe_available:
+            body = (
+                "#!/bin/sh\n"
+                "printf '%s\\n' 'ffprobe unavailable' >&2\n"
+                "exit 127\n"
+            )
+        else:
+            body = (
+                "#!/bin/sh\n"
+                "[ \"${1:-}\" = -version ] || exit 64\n"
+                f"printf '%s\\n' '{executable} fake'\n"
+            )
+        fake.write_text(body, encoding="utf-8")
+        fake.chmod(0o755)
+
+
 def test_compose_has_tty_stdin_and_four_mounts() -> None:
     service = _service()
 
@@ -130,6 +151,17 @@ def test_image_pin_and_application_entrypoint_are_explicit() -> None:
     assert 'ENTRYPOINT ["/usr/local/bin/audiobook-entrypoint"]' in dockerfile
 
 
+def test_image_installs_ffprobe_and_smoke_checks_its_supported_version_flag() -> None:
+    dockerfile = Path("Dockerfile").read_text(encoding="utf-8").replace("\\\n", " ")
+    smoke = Path("scripts/container-smoke.sh").read_text(encoding="utf-8")
+    runtime_install = next(
+        line for line in dockerfile.splitlines() if line.startswith("RUN apk add ")
+    )
+
+    assert "ffmpeg" in runtime_install.split()
+    assert "ffprobe -version" in smoke
+
+
 def test_container_smoke_script_is_copied_to_its_documented_path() -> None:
     dockerfile = Path("Dockerfile").read_text(encoding="utf-8")
     smoke = Path("scripts/container-smoke.sh").read_text(encoding="utf-8")
@@ -162,6 +194,7 @@ def test_container_smoke_upgrade_guard_rejects_each_missing_planner_option(
         encoding="utf-8",
     )
     fake_m4b.chmod(0o755)
+    _write_fake_media_versions(binary_directory)
     help_text = " ".join(option for option in PLANNER_OPTIONS if option != missing)
 
     result = subprocess.run(
@@ -197,6 +230,7 @@ def test_container_smoke_upgrade_guard_accepts_complete_planner_interface(
         encoding="utf-8",
     )
     fake_m4b.chmod(0o755)
+    _write_fake_media_versions(binary_directory)
 
     result = subprocess.run(
         ("sh", "scripts/container-smoke.sh"),
@@ -212,3 +246,36 @@ def test_container_smoke_upgrade_guard_accepts_complete_planner_interface(
     )
 
     assert result.returncode == 0, result.stderr
+
+
+def test_container_smoke_preflight_rejects_unavailable_ffprobe(tmp_path: Path) -> None:
+    binary_directory = tmp_path / "bin"
+    binary_directory.mkdir()
+    fake_m4b = binary_directory / "m4b-tool"
+    fake_m4b.write_text(
+        "#!/bin/sh\n"
+        "if [ \"${1:-}\" = merge ] && [ \"${2:-}\" = --help ]; then\n"
+        "  printf '%s\\n' \"$FAKE_M4B_HELP\"\n"
+        "else\n"
+        "  printf '%s\\n' 'm4b-tool fake'\n"
+        "fi\n",
+        encoding="utf-8",
+    )
+    fake_m4b.chmod(0o755)
+    _write_fake_media_versions(binary_directory, ffprobe_available=False)
+
+    result = subprocess.run(
+        ("sh", "scripts/container-smoke.sh"),
+        env={
+            **os.environ,
+            "PATH": f"{binary_directory}:{os.environ['PATH']}",
+            "FAKE_M4B_HELP": " ".join(PLANNER_OPTIONS),
+            "AUDIOBOOK_SMOKE_OPTION_GUARD_ONLY": "1",
+        },
+        capture_output=True,
+        text=True,
+        check=False,
+    )
+
+    assert result.returncode == 127
+    assert "ffprobe unavailable" in result.stderr