Ingest-spec §4 (ratified D1, commons bfa5a9b) requires a title to reject
`[` and `]` fail-fast at manifest load. The title is rendered verbatim into
the index link label and frontmatter (§5/§6), where a bracket would break
index-link and navigation parsing (method-spec §3 Step 1). The rule was
specced but unenforced: validation only checked single-line.
Satisfies the commons "Title link-safety" load-bearing §11 seam. Same
`manifest_schema` error code as the sibling single-line/max_rows rules;
parametrized cases added to test_manifest and test_error_codes.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016oMpAhQcJZVGBW182stSPn
TDD step 1 of the phase 1 plan: typed error hierarchy rooted in
IngestError, manifest parsing with schema validation before any source
call — id grammar, polymorphic source types, extraction rules, verdict
reservation (okf_type and filename namespace), and the no-embedded-
credentials rule for base_url. Dev tooling (pytest/mypy/ruff) added as
a PEP 735 dependency group; runtime dependencies stay empty.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01QeqhJpYQyghASjiJo5EhGg
