fix(sanitize,okf,active_content): three quadratic patterns, two on the input path

The generalised sweep found what 0.3.2's hand-written rows missed. All three are
the documented class -- a run in front of a required literal that never arrives,
so every start position rescans the tail -- and all three are worse than the
0.3.3 findings, because `sanitize`, `neutralize`, `scan_active_content` and the
okf link graph apply NO input cap. `scan_lexicon`/`scan_output` are the only
entry points that do, so there is no ceiling to extrapolate to.

  sanitize._HTML_COMMENT_RE   `<!--`*100_000        20.1s, exponent 1.96-2.14
  active_content.URL_IN_TEXT_RE  `<a `+`A`*100_000  12.99s / 14.9s, exponent ~2.0
  okf._MD_LINK_RE             `[`*100_000            7.1s, exponent 1.99-2.05

Each fix is the one the pattern's own shape allows, not a copied choice:

  - The comment stripper drops the regex for `str.find`. Excluding `<` would lose
    every comment containing markup; bounding the run would be a carrier bypass
    of the exact construct the stripper exists to remove.
  - `URL_IN_TEXT_RE` bounds its scheme run to an RFC 3986 scheme (`{0,63}`).
    Bounding is safe *here* only because it is a defanger inside a tag already
    flagged `active:raw-html`. A lookbehind was measured too and rejected: it
    drops `-http://evil.com`, a one-character evasion. Bounded: 0.185s at 1M.
  - `_MD_LINK_RE` excludes `[`, matching `active_content.MD_LINK_RE` exactly,
    including the nested-label trade already documented there.

`sanitize` claimed "no catastrophic backtracking" in a comment; that claim was
wrong in the same way `output`'s was before 0.3.2, and is corrected in place.

676 tests (+10), coverage 128/128 + 6/6 gaps, sweep clean across 150 patterns.
The okf destination run gets no row: `[^)\s]+` cannot fail, so a row for it
could never go red.

tests/test_active_content.py

@@ -18,6 +18,8 @@ from __future__ import annotations
 
 import pytest
 
+import time
+
 from llm_ingestion_guard import (
     scan_active_content,
     scan_output,
@@ -294,3 +296,38 @@ def test_raw_html_counts_end_tags():
             if f.label == "active:raw-html"]
     assert len(pair) == 1, "a start/end pair must not split into two findings"
     assert pair[0].count == 2, f"end tag not counted: {pair[0].count}"
+
+
+# --- self-safety (OWASP LLM10): the long-attribute arm -----------------------
+# The `_REDOS_PAYLOADS` rows in test_output.py attack tags that never CLOSE, so
+# `HTML_TAG_RE` fails and the tag body is never handed on. This arm is the
+# opposite: the tag closes, and its body is long. `_tag` then runs
+# `URL_IN_TEXT_RE` over it, whose scheme run sits in front of a required `://`
+# that never arrives — 12.99s at 100_000 chars through this scanner, exponent
+# 1.87-2.06 over four doublings, with no input cap on this entry point at all.
+# Missed by the 0.3.2 sweep because a repeating-unit payload cannot express
+# "one tag, long body"; found by docs/redos-sweep.py generalised past lexicon.
+_ATTR_REDOS_N = 100_000
+
+
+def test_crafted_long_attribute_tag_stays_bounded():
+    payload = "<a " + "A" * _ATTR_REDOS_N + ">"
+    start = time.monotonic()
+    scan_active_content(payload)
+    assert time.monotonic() - start < 2.0
+
+
+def test_url_defanging_survives_the_redos_fix():
+    # Recall parity for the evidence defanger, including the two forms a
+    # lookbehind-based fix would have dropped (`-` / `.` immediately before the
+    # scheme), which is why the scheme run is bounded instead.
+    for raw, expected in (
+        ("<a href=http://evil.com>", "hxxp"),
+        ("<a href=-http://evil.com>", "hxxp"),
+        ("<a href=.http://x.com>", "hxxp"),
+        ('<a href="https://a.b/c">', "hxxps"),
+    ):
+        report = scan_active_content(raw)
+        evidence = " ".join(f.evidence or "" for f in report.findings)
+        assert expected in evidence, raw
+        assert "http://" not in evidence and "https://" not in evidence, raw

tests/test_neutralize.py

@@ -11,6 +11,8 @@ empty report; only active-content constructs are ever rewritten. Mutation lives
 here, kept separate from the report-only output gate (design principles 3 & 4).
 The transform is pure ``text -> (defanged_text, report)`` — no I/O, no globals.
 """
+import time
+
 from llm_ingestion_guard.neutralize import neutralize
 from llm_ingestion_guard.report import Severity, Source
 
@@ -139,3 +141,23 @@ def test_prose_with_lone_brackets_and_angles_is_identical():
     result = neutralize(text)
     assert result.text == text
     assert result.report.found is False
+
+
+# --- self-safety (OWASP LLM10): the long-attribute arm -----------------------
+# Second call site of the same defect pinned in test_active_content.py: the
+# defanger runs `URL_IN_TEXT_RE` over each active tag's body. 14.9s at 100_000
+# chars, exponent 1.91-2.22. `neutralize` applies no input cap either.
+_ATTR_REDOS_N = 100_000
+
+
+def test_crafted_long_attribute_tag_stays_bounded():
+    payload = "<a " + "A" * _ATTR_REDOS_N + ">"
+    start = time.monotonic()
+    neutralize(payload)
+    assert time.monotonic() - start < 2.0
+
+
+def test_url_defanging_inside_a_tag_survives_the_redos_fix():
+    result = neutralize("<a href=-http://evil.com>x</a>")
+    assert "hxxp" in result.text
+    assert "http://evil.com" not in result.text

tests/test_okf.py

@@ -17,6 +17,8 @@ OKF spec facts used here (verified against okf/SPEC.md, 2026-07-06):
 """
 import pytest
 
+import time
+
 from llm_ingestion_guard.okf import (
     parse_frontmatter,
     scan_concept,
@@ -640,3 +642,34 @@ def test_t2_constrains_import_not_emission(fm):
     doc = f"---\nid: x\n{fm}---\n\nbody\n"
     assert import_bundle({"concepts/x.md": doc}).disposition is Disposition.FAIL_SECURE
     assert screen_output(doc, PRESET_USER_UPLOAD).disposition is Disposition.WARN
+
+
+# --- self-safety (OWASP LLM10): ReDoS in the link-graph extractor ------------
+# `[^\]]*` is a run in front of a REQUIRED `]`: a bundle body that repeats `[`
+# and never closes it makes every start position rescan the tail. Measured 7.1s
+# at 100_000 chars, exponent 1.99-2.05 over four doublings, and the link graph
+# runs over attacker-supplied bundle bodies with no input cap. Found by
+# docs/redos-sweep.py once it was generalised past the lexicon table; the same
+# defect in `active_content`'s markdown table was already fixed there the same
+# way, by excluding the character that opens the pattern's own anchor.
+_LINK_REDOS_N = 100_000
+
+
+def test_crafted_link_payload_stays_bounded():
+    start = time.monotonic()
+    extract_link_targets("[" * _LINK_REDOS_N)
+    assert time.monotonic() - start < 2.0
+
+
+# The destination run behind the label gets no row: `[^)\s]+` needs only one
+# character, so it cannot fail, and a run that cannot fail cannot pay the
+# per-start rescan. A row for it could never go red — decoration, not a pin.
+
+
+def test_link_extraction_survives_the_redos_fix():
+    # Recall parity: ordinary links, a label holding brackets it does not close,
+    # and the nested-bracket form the exclusion deliberately gives up on -- the
+    # same trade `active_content.MD_LINK_RE` already makes.
+    assert extract_link_targets("see [x](./a.md) and [y](/b.md)") == ["./a.md", "/b.md"]
+    assert extract_link_targets("[a b](./c.md)") == ["./c.md"]
+    assert extract_link_targets("text [![img](./i.png)](./t.md)") == ["./i.png"]

tests/test_output.py

@@ -436,3 +436,15 @@ def test_gate_is_bounded_on_the_payload_the_first_sweep_missed():
     start = time.monotonic()
     scan_output(payload)
     assert time.monotonic() - start < 2.0
+
+
+def test_gate_is_bounded_on_the_long_attribute_arm():
+    # The composed-gate row for the defect pinned in test_active_content.py and
+    # test_neutralize.py. `scan_output` runs `scan_active_content`, so the gate a
+    # caller actually invokes inherits it. Not expressible as a repeating unit —
+    # the tag has to CLOSE for the body to be handed on — which is exactly why
+    # the unit-table above never covered it.
+    payload = "<a " + "A" * _REDOS_N + ">"
+    start = time.monotonic()
+    scan_output(payload)
+    assert time.monotonic() - start < 2.0

tests/test_sanitize.py

@@ -4,6 +4,8 @@ Core invariants (BRIEF §9): clean input returns byte-identical with an all-zero
 report; the sanitizer only ever *removes* — its output is always a subsequence
 of the input.
 """
+import time
+
 from llm_ingestion_guard.sanitize import sanitize
 from llm_ingestion_guard.report import Severity, Source
 
@@ -75,3 +77,42 @@ def test_data_uri_does_not_match_inside_a_word():
 def test_output_source_is_respected():
     result = sanitize("x​y", source=Source.OUTPUT)
     assert all(f.source is Source.OUTPUT for f in result.report.findings)
+
+
+# --- self-safety (OWASP LLM10): ReDoS on the comment stripper ----------------
+# `sanitize` is step 1 of `prepare_input` -- the first thing every ingested
+# document hits -- and unlike `scan_lexicon`/`scan_output` it applies NO input
+# cap, so a quadratic run here has no ceiling at all. `<!--.*?-->` is a lazy run
+# in front of a REQUIRED literal: crafted input that repeats the opener and never
+# supplies `-->` makes every start position rescan the tail. Measured 20.1s at
+# 100_000 chars, exponent 1.96-2.14 over four doublings. Found by
+# docs/redos-sweep.py once it was generalised past the lexicon table.
+_REDOS_N = 100_000
+
+
+def test_crafted_comment_payload_stays_bounded():
+    payload = ("<!--" * (_REDOS_N // 4 + 1))[:_REDOS_N]
+    start = time.monotonic()
+    sanitize(payload)
+    assert time.monotonic() - start < 2.0
+
+
+def test_legitimate_comment_heavy_document_is_far_under_the_bound():
+    # The bound above only has signal if ordinary comment-dense content is
+    # nowhere near it: this is the same size, 100% closed comments.
+    unit = "<!-- a note -->"
+    payload = (unit * (_REDOS_N // len(unit) + 1))[:_REDOS_N]
+    start = time.monotonic()
+    sanitize(payload)
+    assert time.monotonic() - start < 0.5
+
+
+def test_comment_stripping_survives_the_redos_fix():
+    # Recall parity for every comment shape the lazy regex used to handle:
+    # nested markup, newlines (the pattern was DOTALL), and an unterminated
+    # comment, which must be left alone rather than swallowed to end-of-input.
+    assert sanitize("a <!-- <b>x</b> --> z").text == "a  z"
+    assert sanitize("a <!-- one\ntwo --> z").text == "a  z"
+    assert sanitize("a <!-- x --> b <!-- y --> c").text == "a  b  c"
+    assert sanitize("a <!-- never closed").text == "a <!-- never closed"
+    assert sanitize("a --> b").text == "a --> b"