The slug inherited the whole filename stem with no length bound, so a long
dropped name produced a filename the filesystem cannot hold — surfacing as an
untyped OSError at the write, with an errno that differs per platform (63 on
macOS, 36 on Linux). The inbox contract promises a typed per-file outcome, so
the gate belongs in the pure function that forms the name.
Refusal, not truncation: truncating is lossy AND collision-prone — two long
names sharing a prefix would reduce to one filename and the second write would
silently claim the first file. Same posture as `inbox_slug_empty`: the library
never invents a filename the operator did not give it. The message carries the
actual size and the limit, since the fix is to rename the dropped file.
Limit verified empirically on APFS 2026-07-25: a 255-byte component writes, a
258-byte one raises errno 63. ext4 and NTFS cap at the same 255.
New MaterializationError code `inbox_slug_too_long`, registered in the errors
docstring and in the error-code conformance suite.
Second guard-independent step of Phase 2: the pure functions that turn a
dropped file's name and extracted text into an OKF concept file, with the
§7-analogous honesty marker. No runtime dependency, no guard call, no model
call — the persist gate is still steps 4–5.
- `inbox_slug(filename)` reduces a name to the Phase 1 id grammar
(`[a-z0-9][a-z0-9-]*`): drop the final extension, lowercase, collapse every
run of non-grammar characters to one `-`, strip the ends. A name that
reduces to nothing fails fast rather than inventing an `untitled` fallback
that would silently collide across unrelated files.
- `inbox_filename(slug)` namespaces it `inbox-{slug}.md`, disjoint from
`index.md`, Door A's `ingest-*`, and `promoted-verdict-*` for every slug the
grammar admits (asserted over a hostile-name table, not one example).
- `render_inbox_concept(...)` emits the six-key layer in fixed order — `type`,
`title`, `source_file`, `source_sha256`, `ingested_at`, `generated: true` —
with the digest taken over the ORIGINAL dropped bytes, never the extracted
text, so provenance stays re-verifiable against the operator's file. Body is
normalised to LF-only with exactly one trailing newline (dropped files
legitimately arrive with CRLF; Door A can validate instead because it renders
its own bodies).
Slugging normalises to NFC first. macOS (APFS) hands filenames over
decomposed, so `é` arrives as `e` + combining acute: without normalising, the
combining mark alone becomes a separator and the base letter survives
(`cafe`), where the composed form is one non-grammar character (`caf`) — one
visual filename, two slugs, depending on where the string came from. The test
pins both forms with explicit escapes so it cannot depend on the test file's
own encoding. No transliteration, deliberately: mapping non-ASCII to ASCII is
a semantic claim the slugger cannot make (Norwegian `møte`/meeting would
become `mote`/fashion). The readable name survives verbatim in `title`.
Fail-fast gates, all typed: reserved `verdict` layer refused at this door too
(the promotion gate stays the only path in); a title that is multi-line or
contains `[`/`]` refused, matching Door A's manifest rule, because it renders
verbatim into `- [title](target)`; a multi-line `source_file` refused because
line-oriented frontmatter would take the injected lines. Four new stable
MaterializationError codes, each with its entry in the test_error_codes.py
registry: `inbox_slug_empty`, `inbox_title_invalid`,
`inbox_source_file_invalid`, `okf_type_reserved`.
`ingested_at` validation moves to a shared `validate_ingested_at` in
materialize.py and is called by both doors — one rule in one place is what
keeps the determinism contract from drifting apart per door.
TDD: tests/test_inbox.py precedes the implementation. 325 tests green;
mypy --strict, ruff check/format, and the sanitize|quarantine|lexicon
boundary grep-gate clean; runtime dependencies still exactly none; the Phase 1
golden suite still passes byte-for-byte.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01A2aKJxLejT9S8jYwoZ9fut
