Say metadata check and strip results are not a clean verdict

docs/cli.md

@@ -157,6 +157,11 @@ remove-ai-watermarks metadata image.png --remove -o clean.png
 When `-o` is omitted, removal overwrites the source. Standard metadata is kept
 unless you pass `--remove-all`.
 
+A quiet `--check` or a successful `--remove` is not a clean verdict. The command
+only inspects and strips embedded AI metadata; a pixel watermark such as SynthID
+has no local decoder once that metadata proxy is gone. `identify` reports the
+same limit.
+
 The command also supports the audio and video containers listed in
 [supported signals](supported-signals.md). ffmpeg must be available for the
 non-ISOBMFF audio and video path.
@@ -225,6 +230,10 @@ remove-ai-watermarks video metadata input.mp4 --check
 remove-ai-watermarks video metadata input.mp4 --remove -o clean.mp4
 ```
 
+As with the generic `metadata` command, a quiet check or a successful strip is
+not a clean verdict: video SynthID is not decoded locally after the metadata
+proxy is gone.
+
 Supported containers are MP4, MOV, M4V, WebM, MKV, AVI, and FLV. The operation
 delegates to the same verified metadata scanner and stripper as the generic
 `metadata` command, so detection and removal stay in parity. Video and audio

docs/module-internals.md

@@ -42,6 +42,10 @@ Important contracts:
 - `invisible` writes no output when no supported local signal is found, unless
   `--force` is supplied.
 - The two no-signal conditions currently share exit code `2`.
+- A quiet `metadata --check` and a successful `metadata --remove` (same for
+  `video metadata`) end by repeating the `identify` limit: the pixel channel is
+  untouched and a watermark such as SynthID has no local decoder once its
+  metadata proxy is gone, so neither outcome is a clean verdict.
 - Hard processing and write failures exit with code `1`.
 - `all` can still write the completed visible and metadata stages when the
   diffusion dependencies are unavailable, but exits with code `1` so the

src/remove_ai_watermarks/cli.py

@@ -904,10 +904,27 @@ def cmd_invisible(
 
 
 # ── Metadata operations ──
+def _print_metadata_not_a_clean_verdict() -> None:
+    """Repeat the identify empty-scan limit on metadata check and strip success.
+
+    ``metadata --check`` and ``metadata --remove`` answer a narrower question than
+    ``identify``: they report embedded AI metadata only. A quiet result used to
+    stop at "No AI metadata found" / "AI metadata stripped", which readers treat
+    as a clean-image verdict. The pixel channel is unchanged, and this project has
+    no local SynthID decoder, so the command must say so in the same words
+    ``identify`` already uses.
+    """
+    console.print(
+        "  This is not the same as 'clean': a pixel watermark such as SynthID cannot be\n"
+        "  detected here once its metadata proxy is absent."
+    )
+
+
 def _print_metadata_report(source: Path, has_ai: bool, metadata: dict[str, str]) -> None:
     """Render one metadata inspection result for the generic and video commands."""
     if not has_ai:
         console.print(f"  No AI metadata found in {source.name}")
+        _print_metadata_not_a_clean_verdict()
         return
 
     console.print(f"  Warning: AI metadata detected in {source.name}:")
@@ -974,6 +991,7 @@ def cmd_metadata(
         console.print("    the file could not be decoded, so it was copied through unchanged")
         raise SystemExit(1)
     console.print(f"  AI metadata stripped -> {out}")
+    _print_metadata_not_a_clean_verdict()
 
 
 # ── Video pipeline ──
@@ -1115,6 +1133,7 @@ def cmd_video_metadata(
         console.print(f"    still present: {', '.join(sorted(result.remaining))}")
         raise SystemExit(1)
     console.print(f"  AI metadata stripped -> {result.output}")
+    _print_metadata_not_a_clean_verdict()
 
 
 @cmd_video.command("invisible")

tests/test_cli.py

@@ -629,11 +629,13 @@ class TestMetadataCommand:
         result = runner.invoke(main, ["metadata", str(tmp_clean_png), "--check"])
         assert result.exit_code == 0
         assert "No AI metadata" in result.output
+        assert "not the same as 'clean'" in result.output
 
     def test_metadata_check_ai(self, runner, tmp_png_with_ai_metadata):
         result = runner.invoke(main, ["metadata", str(tmp_png_with_ai_metadata), "--check"])
         assert result.exit_code == 0
         assert "AI metadata detected" in result.output
+        assert "not the same as 'clean'" not in result.output
 
     def test_metadata_remove(self, runner, tmp_png_with_ai_metadata, tmp_path):
         output = tmp_path / "stripped.png"
@@ -649,6 +651,7 @@ class TestMetadataCommand:
         )
         assert result.exit_code == 0
         assert "stripped" in result.output
+        assert "not the same as 'clean'" in result.output
 
     def test_metadata_remove_reports_failure_when_the_strip_was_a_no_op(self, runner, tmp_path):
         """A file PIL cannot decode is copied through UNCHANGED by the fail-safe.

tests/test_video.py

@@ -951,6 +951,7 @@ class TestVideoMetadataCli:
 
         assert result.exit_code == 0, result.output
         assert "AI metadata detected" in result.output
+        assert "not the same as 'clean'" not in result.output
 
     def test_remove_reports_output(self, tmp_path: Path):
         runner = CliRunner()
@@ -961,6 +962,7 @@ class TestVideoMetadataCli:
 
         assert result.exit_code == 0, result.output
         assert "AI metadata stripped" in result.output
+        assert "not the same as 'clean'" in result.output
         assert C2PA_UUID not in output.read_bytes()
 
     def test_rejects_image_input(self, tmp_clean_png: Path):