fix(core): split comma-separated tags in parse_tags

src/basic_memory/utils.py

@@ -526,8 +526,20 @@ def parse_tags(tags: Union[List[str], str, None]) -> List[str]:
 
     # Process list of tags
     if isinstance(tags, list):
-        # First strip whitespace, then strip leading '#' characters to prevent accumulation
-        return [tag.strip().lstrip("#") for tag in tags if tag and tag.strip()]
+        # Trigger: a list element may itself be a comma-separated string (e.g. typer collects
+        #   `--tags "a,b"` into the one-element list `["a,b"]`).
+        # Why: keep the CLI list path and the MCP bare-string path on a single source of truth so
+        #   `--tags "a,b"`, `--tags a --tags b`, and `tags="a,b"` all converge to the same tags.
+        # Outcome: flatten by splitting each element on commas before stripping '#' / whitespace.
+        # Skip None entries (e.g. a YAML `tags: [alpha, null]`) so they are not revived as
+        # the literal tag "None" by str(raw); the old list branch ignored such falsy entries.
+        return [
+            tag.strip().lstrip("#")
+            for raw in tags
+            if raw is not None
+            for tag in str(raw).split(",")
+            if tag and tag.strip()
+        ]
 
     # Process string input
     if isinstance(tags, str):

test-int/bughunt_fixes/test_parse_tags_comma_split_integration.py

@@ -0,0 +1,81 @@
+"""Bug: CLI `write-note --tags "a,b"` does NOT split the comma string, but the
+MCP write_note(tags="a,b") DOES (parse_tags splits a bare string but treats each
+list element as a single literal tag).
+
+Typer collects a single --tags value into a one-element list ['a,b'], and
+parse_tags(['a,b']) returns ['a,b'] (no per-element comma split). The MCP tool
+receives the bare string 'a,b' and parse_tags('a,b') returns ['a','b'].
+
+Result: the SAME comma-string input yields different tags on CLI vs MCP, even
+though write_note's docstring promises comma-separated-string support.
+"""
+
+import json
+import pytest
+from fastmcp import Client
+from typer.testing import CliRunner
+from basic_memory.cli.main import app as cli_app
+
+runner = CliRunner()
+
+
+def test_cli_write_note_comma_tags_split_matches_mcp(app, app_config, test_project, config_manager):
+    # CLI: single --tags value containing a comma
+    write = runner.invoke(
+        cli_app,
+        [
+            "tool",
+            "write-note",
+            "--title",
+            "CLI Comma Split",
+            "--folder",
+            "cli-comma-split",
+            "--content",
+            "# CLI Comma Split\n\nbody",
+            "--tags",
+            "alpha,beta",
+        ],
+    )
+    assert write.exit_code == 0, write.output
+    permalink = json.loads(write.stdout)["permalink"]
+
+    read = runner.invoke(
+        cli_app,
+        ["tool", "read-note", permalink, "--include-frontmatter", "--local"],
+    )
+    assert read.exit_code == 0, read.output
+    content = json.loads(read.stdout)["content"]
+
+    # Correct behavior: two distinct tags (matching MCP write_note semantics).
+    # splitlines() is line-ending agnostic (Windows CRLF vs POSIX LF).
+    content_lines = content.splitlines()
+    assert "- alpha" in content_lines and "- beta" in content_lines, (
+        "CLI --tags 'alpha,beta' should split into two tags like MCP write_note does; "
+        f"got frontmatter:\n{content}"
+    )
+    assert "alpha,beta" not in content, "comma string must not survive as a single literal tag"
+
+
+@pytest.mark.asyncio
+async def test_mcp_write_note_comma_tags_split_baseline(mcp_server, app, test_project):
+    """Baseline: MCP write_note DOES split comma strings (the behavior CLI should match)."""
+    async with Client(mcp_server) as client:
+        await client.call_tool(
+            "write_note",
+            {
+                "project": test_project.name,
+                "title": "MCP Comma Split",
+                "directory": "mcp-comma-split",
+                "content": "# MCP Comma Split\n\nbody",
+                "tags": "alpha,beta",
+            },
+        )
+        read = await client.call_tool(
+            "read_note",
+            {"project": test_project.name, "identifier": "MCP Comma Split"},
+        )
+        text = read.content[0].text
+        text_lines = text.splitlines()
+        assert "- alpha" in text_lines and "- beta" in text_lines, (
+            f"MCP write_note should split comma string into two tags; got:\n{text}"
+        )

tests/utils/test_parse_tags.py

@@ -17,6 +17,11 @@
         (["tag1", "tag2"], ["tag1", "tag2"]),
         (["tag1", "", "tag2"], ["tag1", "tag2"]),  # Empty tags are filtered
         ([" tag1 ", " tag2 "], ["tag1", "tag2"]),  # Whitespace is stripped
+        # Comma inside a single list element is split (CLI `--tags "a,b"` -> ["a,b"])
+        (["tag1,tag2"], ["tag1", "tag2"]),
+        (["tag1, tag2", "tag3"], ["tag1", "tag2", "tag3"]),
+        # None entries (e.g. YAML `tags: [alpha, null]`) are skipped, not revived as "None"
+        (["alpha", None], ["alpha"]),
         # String inputs
         ("", []),
         ("tag1", ["tag1"]),