fix(storage): JSON-serialize date/datetime metadata from YAML frontmatter#25
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torresmateo merged 2 commits intoMay 21, 2026
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…tter
Obsidian and other markdown frontmatter commonly contain `YYYY-MM-DD`
values that PyYAML parses into `datetime.date`, e.g.:
---
last_push: 2026-05-19
---
When `MarkdownParser` extracted the frontmatter and `Database.insert_document`
ran `json.dumps(document.metadata)`, this crashed with:
TypeError: Object of type date is not JSON serializable
Add a small `_json_default` fallback that converts `date` / `datetime`
to ISO strings (and falls back to `str()` for anything else). Round-tripped
values come back as strings — acceptable because metadata is informational
and not queried as dates.
Includes a regression test that fails before this change and passes after,
covering both `insert_document` and `update_document`.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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torresmateo
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May 21, 2026
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This LGTM with the exception of a small Python style issue!
torresmateo
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May 21, 2026
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What
Database.insert_documentandupdate_documentcalljson.dumps(document.metadata)to persist parsed-frontmatter metadata. Frontmatter dates likelast_push: 2026-05-19are parsed by PyYAML intodatetime.dateobjects, which the stdlib JSON encoder doesn't know how to handle, so any markdown file with a date in frontmatter fails to index:```
TypeError: Object of type date is not JSON serializable
```
Repro
Hits anyone using Obsidian (very common to have
created: YYYY-MM-DDor similar in frontmatter). A minimal example:```
title: My note
last_push: 2026-05-19
```
`librarian add /path/to/that/note.md` → `Error: ... Object of type date is not JSON serializable`.
Fix
Pass a small `default=` callback to `json.dumps` that converts `date` / `datetime` to ISO strings, and `str()`'s anything else unexpected. Stored as strings; round-tripped values come back as strings — acceptable because metadata is informational, not queried as dates.
Tests
New `tests/test_database.py` with regression tests for both `insert_document` and `update_document`. Verified the tests fail on `main` (reproducing `TypeError`) and pass with this change. Existing `test_parser.py` continues to pass.
Notes