feat(okf): read_provenance names WHY a signal is unreadable, on the SkippedLink shape

Co-Authored-By: Claude <claude-opus-5>
This commit is contained in:
Kjell Tore Guttormsen 2026-09-02 20:16:01 +02:00
commit 7552be239b
2 changed files with 216 additions and 9 deletions

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@ -29,6 +29,7 @@ never written.
from __future__ import annotations
import itertools
import json
import posixpath
import re
@ -370,6 +371,96 @@ class SkippedLink:
reason: SkipReason
#: WHY a provenance value could not be read. The tokens name the SHAPE the value is written in
#: and NOTHING else — the same discipline ``SkipReason`` carries. A block sequence and a block
#: mapping are both CONFORMANT OKF (SPEC §5.2 writes ``verified`` in exactly those forms); they are
#: simply outside the accepted single-line subset, and this decoder is not entitled to an opinion
#: about whether the author erred. ``unsupported-flow`` is the one token that does denote a
#: malformation, and it says so by naming the flow FORM rather than the author.
ProvenanceReason = Literal["block-sequence", "block-mapping", "unsupported-flow"]
@dataclass(frozen=True)
class UnreadableProvenance:
"""A provenance key that IS present and could NOT be read, and why — never silence.
Mirrors ``SkippedLink``: structured rather than a rendered string, for the reason
``BudgetExceeded`` carries ``kind``/``limit``/``observed`` as fields (kø-(y)). "Which shape is
this written in" and "how many entries were there" are two separate operative questions, and a
caller forced to re-parse a token to tell them apart has been handed a diagnostic it cannot act
on. That is why the COUNT is its own field and is never folded into the token.
``value`` is the offending text VERBATIM as written in the file, indentation included — the
operator fixing the document edits that text, and a normalised form would send them looking for
a string their file does not contain."""
#: Path of the document the key was read from.
file: str
#: The frontmatter key that could not be read.
key: str
#: The offending text exactly as it appears in that file.
value: str
reason: ProvenanceReason
#: Entries seen. ``0`` when nothing countable was there — an empty key, or a flow value the
#: decoder refused and therefore never enumerated.
items_seen: int
def read_provenance(
path: str | Path, key: str
) -> tuple[dict[str, str], ...] | UnreadableProvenance | None:
"""Read one provenance key into entries, or say why it could not be read.
Three outcomes, and the three-way split is the whole point:
* ``None`` — the document does not carry the key. **Absence is ``None``, never a default**:
the F2 principle one layer down, where an unread signal must not become an asserted absent
one.
* a tuple of entries — the value was in the accepted flow subset and decoded.
* ``UnreadableProvenance`` — the key is THERE and could not be read, with the shape and the
count that say what was seen.
Driven by ``_split_frontmatter``: this is a second READER of the one parse, never a second
parser. Only top-level (unindented) frontmatter lines are considered as key sites, so an
indented ``by:`` inside a block entry can never be mistaken for a document-level key.
Gated by ``tests/test_provenance_decoder_loadbearing.py``."""
lines = _split_frontmatter(Path(path).read_text(encoding="utf-8"))[0]
for i, line in enumerate(lines):
if line[:1] in (" ", "\t"):
continue
name, sep, raw = line.partition(":")
if not sep or name.strip() != key:
continue
value = raw.strip()
if value:
try:
return decode_flow_value(value, key=key)
except FlowDecodeError:
return UnreadableProvenance(
file=str(path), key=key, value=value, reason="unsupported-flow", items_seen=0
)
continuation = list(itertools.takewhile(lambda ln: ln[:1] in (" ", "\t"), lines[i + 1 :]))
if not continuation:
return UnreadableProvenance(
file=str(path), key=key, value="", reason="block-mapping", items_seen=0
)
# An ITEM is a continuation line whose STRIPPED form opens with ``- ``. A ``- `` occurring
# inside a value is text, not an item, and counting it would inflate the number the caller
# acts on.
items = sum(1 for ln in continuation if ln.strip().startswith("- "))
return UnreadableProvenance(
file=str(path),
key=key,
value="\n".join(continuation),
# SPEC §5.2's one-element MUST: a bare mapping IS one entry, so a mapping that is
# present counts 1 rather than 0 — 0 is reserved for "nothing was there at all".
reason="block-sequence" if items else "block-mapping",
items_seen=items or 1,
)
return None
@dataclass(frozen=True)
class Bundle:
"""A navigated OKF bundle: ``index.md`` plus every cross-linked file that resolves — and, in

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@ -18,6 +18,8 @@ means unchanged against a measurement rather than against a recollection.
from __future__ import annotations
import ast
import itertools
import tempfile
from pathlib import Path
import pytest
@ -67,6 +69,17 @@ _EXPECTED_BODY: dict[str, str] = {
}
_FIXTURE_COUNTER = itertools.count()
def _fixture(text: str) -> Path:
"""A throwaway document on disk. The accessor reads FILES, so an in-memory string would test a
different function than the one shipped."""
path = Path(tempfile.mkdtemp(prefix="okf-provenance-")) / f"c{next(_FIXTURE_COUNTER)}.md"
path.write_text(text, encoding="utf-8")
return path
def _write(tmp_path: Path, shape: str) -> Path:
path = tmp_path / f"{shape}.md"
path.write_text(_SHAPES[shape], encoding="utf-8")
@ -161,13 +174,14 @@ def test_load_file_reads_each_file_once(tmp_path: Path) -> None:
def test_the_parsed_dict_loses_what_the_accessor_recovers(tmp_path: Path) -> None:
"""AMENDMENT C — the leak, shown by putting both readers on the SAME file in ONE arm.
``parse_frontmatter`` hands back ``""`` for a block-form ``verified``; the provenance accessor
hands back the shape and the entry count. Asserting only the accessor's answer would leave the
*reason the accessor exists* undocumented, and the reason is the whole of condition 2.
``parse_frontmatter`` hands back ``""`` for a block-form ``verified``; the accessor hands back
the SHAPE and the COUNT. Asserting only the accessor's answer would leave the *reason the
accessor exists* undocumented, and the reason is the whole of condition 2.
``read_provenance`` arrives in Step 4. This arm is AUTHORED here and ENABLES ITSELF the moment
the symbol exists — a self-enabling skip rather than a TODO, because a note in prose is a note
somebody has to remember to act on.
Authored in Step 2 against an accessor that did not exist yet, and it ENABLED ITSELF when the
symbol arrived in Step 4 — a self-enabling skip rather than a TODO. What the arm asserts was
corrected at that point: an unreadable value yields ``UnreadableProvenance``, not entries, and
a test that had guessed otherwise would have been a test written against an imagined API.
"""
read_provenance = getattr(okf, "read_provenance", None)
if read_provenance is None:
@ -176,9 +190,9 @@ def test_the_parsed_dict_loses_what_the_accessor_recovers(tmp_path: Path) -> Non
path = _write(tmp_path, "block")
assert parse_frontmatter(path)["verified"] == ""
provenance = read_provenance(path, key="verified")
assert provenance.entries, "the accessor recovered nothing the parser had already lost"
assert len(provenance.entries) == 2
provenance = read_provenance(path, "verified")
assert isinstance(provenance, okf.UnreadableProvenance)
assert (provenance.reason, provenance.items_seen) == ("block-sequence", 2)
# --- Step 3: the flow-form decoder ------------------------------------------------------------
@ -315,3 +329,105 @@ def test_a_verified_entry_with_no_actor_is_refused() -> None:
assert okf.decode_flow_value("{ at: 2026-01-01T00:00:00Z }", key="sources") == (
{"at": "2026-01-01T00:00:00Z"},
)
# --- Step 4: the provenance accessor and its reason vocabulary --------------------------------
_FIXTURE_BUNDLE = (
Path(__file__).resolve().parents[1] / "tests" / "golden" / "block-form-provenance" / "bundle"
)
def test_a_single_entry_block_sequence_reports_shape_and_count() -> None:
"""The committed fixture's one-entry block ``verified``: the PAIR is asserted, not the token.
``reason`` alone cannot tell a one-entry list from a five-entry one, and the count alone cannot
say which shape produced it. Together they are strictly more information than a single
``block-form``/``multi-entry`` token, and neither half mislabels the other.
"""
result = okf.read_provenance(_FIXTURE_BUNDLE / "attested.md", "verified")
assert isinstance(result, okf.UnreadableProvenance)
assert (result.reason, result.items_seen) == ("block-sequence", 1)
assert result.key == "verified"
def test_a_two_entry_block_sequence_counts_both() -> None:
"""The same shape, a different count — which is what makes ``items_seen`` a real discriminator."""
result = okf.read_provenance(_FIXTURE_BUNDLE / "multi-verified.md", "verified")
assert isinstance(result, okf.UnreadableProvenance)
assert (result.reason, result.items_seen) == ("block-sequence", 2)
def test_a_block_mapping_is_named_a_mapping_not_a_sequence() -> None:
"""Both shapes are CONFORMANT OKF and merely outside the accepted subset.
The tokens name the shape the value is written in and nothing else — the decoder is not
entitled to an opinion about whether the author erred, and a token that implied one would file
this repo's own SPEC-canonical fixture as a defect.
"""
path = _fixture(
"---\ntype: concept\nverified:\n by: human:a\n at: 2026-01-01T00:00:00Z\n---\nbody\n"
)
result = okf.read_provenance(path, "verified")
assert isinstance(result, okf.UnreadableProvenance)
assert (result.reason, result.items_seen) == ("block-mapping", 1)
def test_a_key_with_an_empty_value_and_no_continuation_counts_nothing() -> None:
"""``verified:`` with nothing under it saw zero entries, and says so."""
path = _fixture("---\ntype: concept\nverified:\ntitle: x\n---\nbody\n")
result = okf.read_provenance(path, "verified")
assert isinstance(result, okf.UnreadableProvenance)
assert (result.reason, result.items_seen) == ("block-mapping", 0)
def test_a_flow_value_the_decoder_refuses_is_named_unsupported_flow() -> None:
"""``unsupported-flow`` is the ONE token that denotes a malformation, and it names the FORM."""
path = _fixture("---\ntype: concept\nsources: [ a.pdf, b.pdf ]\n---\nbody\n")
result = okf.read_provenance(path, "sources")
assert isinstance(result, okf.UnreadableProvenance)
assert result.reason == "unsupported-flow"
assert result.value == "[ a.pdf, b.pdf ]"
def test_a_readable_flow_value_comes_back_decoded() -> None:
"""CONTROL — an accessor that only ever answered ``UnreadableProvenance`` would pass every
negative arm above and be worthless."""
path = _fixture(
"---\ntype: concept\nsources: [{ id: golden-v0-2-sales, resource: fixture }]\n---\nbody\n"
)
assert okf.read_provenance(path, "sources") == (
{"id": "golden-v0-2-sales", "resource": "fixture"},
)
def test_an_absent_key_is_None_never_a_default() -> None:
"""Absence is ``None`` — the F2 principle one layer down.
An unread signal must not become an asserted absent one: ``None`` says "this document does not
carry the key", which is a different fact from "the key is there and unreadable" and from
"the key is there and empty".
"""
path = _fixture("---\ntype: concept\ntitle: x\n---\nbody\n")
assert okf.read_provenance(path, "sources") is None
def test_a_literal_dash_inside_a_value_does_not_inflate_the_count() -> None:
"""An item is a continuation line whose STRIPPED form starts with ``- ``, not a substring."""
path = _fixture("---\ntype: concept\nverified:\n by: human:a - reviewed - twice\n---\nbody\n")
result = okf.read_provenance(path, "verified")
assert isinstance(result, okf.UnreadableProvenance)
assert (result.reason, result.items_seen) == ("block-mapping", 1)
def test_the_offending_text_is_carried_verbatim() -> None:
"""``value`` is what the operator will edit, indentation included — never a normalised form
that would send them looking for a string their file does not contain (the ``SkippedLink``
rule, applied one layer down)."""
path = _fixture(
"---\ntype: concept\nverified:\n - { by: human:a, at: 2026-01-01T00:00:00Z }\n---\nbody\n"
)
result = okf.read_provenance(path, "verified")
assert isinstance(result, okf.UnreadableProvenance)
assert result.value == " - { by: human:a, at: 2026-01-01T00:00:00Z }"
assert result.file == str(path)