feat(reports): the model's own suspicion band is a proposal too

contributor-scan 2.17, completing Req 5.5.

Task 2.11 made static pattern matches proportionate and left the model
layer's own suspicions alone, reasoning that a proposer had reasoned about
them. That does not survive inspection. A model suspicion is what the
enumerator proposed at a site the graph could NOT decide, affirmed by a
judge with no coverage there -- and its own rationale says exactly that:
"the model resolved no flow here; its sink table may not cover this API".
It is a pattern match with an opinion attached, and it reads like a
reasoned claim only because a model produced it.

  vampi    60 findings, 61 sections -> 26, report 1085 lines -> 446
  libpng   198 findings, 39 sections -> 30

**What it costs, which is the number that decides whether the rule is
right.** For each known vulnerability the recipe declares, take every
finding row at its location and ask whether any survives the rule. All
three of vampi's -- the SQL injection and both documented BOLAs -- are
still found at model_entailed and all three survive. Nothing known is
hidden. Three vulnerabilities in one repository is also a statement about
how small the evidence base is, and the artifact says so.

The obligations checker sits at `suspicion` too and is NOT grouped: its
output comes from a structural analysis, an obligated operation with no
discharging guard, rather than from a guess. An earlier attempt at this
rule filtered on rung alone and would have collapsed it; six tests failed
and they were right to.

"Pattern matches" is now "Proposed, not corroborated", since it holds two
shapes. Model rows group by FAMILY rather than by rule, because their rule
is always `model`.

Gates byte-identical.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01T7XD7x5KonMdmGRkp63EQG

.kiro/specs/contributor-scan/tasks.md

@@ -318,7 +318,7 @@
   - _Requirements: 3.1, 8.2_
   - _Depends: 2.15_
 
-- [ ] 2.17 The model's own suspicion band is a pattern match with an opinion attached
+- [x] 2.17 The model's own suspicion band is a pattern match with an opinion attached
   - **Req 5.5's other half.** Task 2.11 made pattern matches proportionate and left this untouched, so vampi
     still emits 61 sections for a 520-line application -- 38 of them model suspicions, roughly one per
     fourteen lines of code.

benchmarks/measurements/2026-09-09-report-proportionality-model-band.json

@@ -0,0 +1,25 @@
+{
+  "generated": "2026-09-09",
+  "measured": {
+    "libpng": {
+      "findings": 198,
+      "sections_after_2_11": 39,
+      "sections_after_2_17": 30
+    },
+    "vampi": {
+      "findings": 60,
+      "report_lines": "1085 -> 446",
+      "sections_after": 26,
+      "sections_before": 61
+    }
+  },
+  "reading": "Task 2.11 made static pattern matches proportionate and left the model layer's own suspicions alone, on the reasoning that a proposer had reasoned about them. That reasoning does not survive inspection: a model suspicion is what the enumerator proposed at a site the graph could NOT decide, affirmed by a judge with no coverage there. Its own rationale says so -- 'the model resolved no flow here; its sink table may not cover this API'. It is a pattern match with an opinion attached, and it reads like a reasoned claim only because a model produced it.",
+  "spec": "contributor-scan 2.17 (Req 5.5) -- the model's own suspicion band",
+  "the_section_renamed": "'Pattern matches' became 'Proposed, not corroborated', because it now holds two shapes: a static pattern saying an API is present, and a candidate the model could not decide. Model rows group by FAMILY rather than by rule, since their rule is always `model`.",
+  "what_is_not_grouped": "The obligations checker also sits at `suspicion`, and is NOT grouped. Its output comes from a structural analysis -- an obligated operation with no discharging guard -- rather than from a guess. An earlier attempt at this rule filtered on rung alone and would have collapsed it; six tests failed and they were right to.",
+  "what_it_costs": {
+    "caveat": "Three known vulnerabilities in one repository. The rule would hide a real finding that only ever reached model-suspicion, and no such finding exists in the evidence base -- which is a statement about how small the evidence base is as much as about the rule.",
+    "method": "For each known vulnerability the recipe declares, take every finding row at its location and ask whether any survives the rule. If a known vulnerability appeared ONLY at model-suspicion, this rule hides it, and that is the number that decides whether the rule is right.",
+    "result": "VAmPI-SQLI, VAmPI-BOLA and VAmPI-BOLA-BOOKS all still found at model_entailed and all three survive the rule. Nothing known is hidden."
+  }
+}

src/openultrasast/reports.py

@@ -385,13 +385,8 @@ def _crowded_pattern_rules(findings: Sequence[StaticFinding]) -> list[StaticFind
     counts: dict[str, int] = {}
     for finding in findings:
         if _is_pattern_only(finding):
-            rule = str(finding.finding_id).split(":", 1)[0]
-            counts[rule] = counts.get(rule, 0) + 1
-    return [
-        finding
-        for finding in findings
-        if _is_pattern_only(finding) and counts.get(str(finding.finding_id).split(":", 1)[0], 0) > _PATTERN_DETAIL_LIMIT
-    ]
+            counts[_rule_key(finding)] = counts.get(_rule_key(finding), 0) + 1
+    return [finding for finding in findings if _is_pattern_only(finding) and counts.get(_rule_key(finding), 0) > _PATTERN_DETAIL_LIMIT]
 
 
 def _append_coverage(lines: list[str], coverage: Sequence[Mapping[str, object]]) -> None:
@@ -425,30 +420,51 @@ def _append_coverage(lines: list[str], coverage: Sequence[Mapping[str, object]])
 
 
 def _is_pattern_only(finding: StaticFinding) -> bool:
-    """Is a text match the only thing behind this finding?
+    """Was this proposed with nothing corroborating it?
 
-    `static_corroboration` is what the static layer emits when a pattern matched and nothing else spoke. A
-    proposer that reasoned about the site -- the model layer, the obligations checker -- carries `suspicion`
-    here even when its rung is also suspicion, and that is the distinction: an undecided CLAIM is not the
-    same as an observation that an API is present.
+    Two shapes qualify, and the second took a second look to see.
+
+    A **static pattern match** (`static_corroboration` at `suspicion`) says an API is present.
+
+    A **model suspicion** (`model:` at `suspicion`) is what the enumerator proposed at a site the graph could
+    NOT decide, affirmed by a judge that has no coverage there -- a pattern match with an opinion attached.
+    Its rationale says so in its own words: "the model resolved no flow here; its sink table may not cover
+    this API". It reads like a reasoned claim because a model produced it, which is exactly why it needs
+    naming: on vampi it is 38 of 60 findings, roughly one per fourteen lines of a 520-line application.
+
+    What does NOT qualify is the obligations checker, which also sits at `suspicion`. Its output comes from a
+    structural analysis -- an obligated operation with no discharging guard -- rather than from a guess, and
+    collapsing it would hide a detector.
     """
-    return str(finding.evidence_level) == "static_corroboration" and str(finding.rung) == "suspicion"
+    if str(finding.rung) != "suspicion":
+        return False
+    if str(finding.evidence_level) == "static_corroboration":
+        return True
+    return str(finding.finding_id).startswith("model:")
+
+
+def _rule_key(finding: StaticFinding) -> str:
+    """How a proposal is grouped. Model findings key on their FAMILY, since their rule is always `model`."""
+    parts = str(finding.finding_id).split(":")
+    if parts and parts[0] == "model" and len(parts) > 1:
+        return f"model:{parts[1]}"
+    return parts[0] if parts else ""
 
 
 def _append_pattern_matches(lines: list[str], patterned: Sequence[StaticFinding]) -> None:
     """Pattern matches, grouped by rule. Proportionate: few sites are named, many are counted."""
     by_rule: dict[str, list[StaticFinding]] = {}
     for finding in patterned:
-        by_rule.setdefault(str(finding.finding_id).split(":", 1)[0], []).append(finding)
+        by_rule.setdefault(_rule_key(finding), []).append(finding)
 
     lines.extend(
         [
-            "## Pattern matches",
+            "## Proposed, not corroborated",
             "",
-            f"{len(patterned)} site(s) matched a static pattern with nothing corroborating them. A match says "
-            "an API is present, not that it is misused; the model reached none of these, and silence from the "
-            "model means no fact table covered the site rather than that it is safe. All of them are in "
-            "`findings.json`.",
+            f"{len(patterned)} site(s) were proposed with nothing corroborating them: a static pattern saying "
+            "an API is present, or a candidate the model could not decide and a judge affirmed without "
+            "coverage there. Neither says the site is misused. Silence from the model means no fact table "
+            "covered it rather than that it is safe, and all of them are in `findings.json`.",
             "",
         ]
     )

tests/test_reports.py

@@ -485,7 +485,7 @@ def test_a_pattern_rule_with_many_sites_is_summarised_not_repeated(tmp_path: Pat
     write_markdown_report(crowded, output)
 
     text = output.read_text()
-    assert "## Pattern matches" in text
+    assert "## Proposed, not corroborated" in text
     assert "20 site(s) across 20 file(s)" in text
     assert text.count("## c-unsafe-copy needs review") == 0, "twenty sections for one rule is the noise"
     assert "`findings.json`" in text, "counted, never dropped"
@@ -499,7 +499,7 @@ def test_a_pattern_rule_with_few_sites_keeps_its_sections(tmp_path: Path) -> Non
 
     text = output.read_text()
     assert "## python-flask-debug needs review" in text
-    assert "## Pattern matches" not in text
+    assert "## Proposed, not corroborated" not in text
 
 
 def test_a_reasoned_claim_keeps_its_section_whatever_its_rung(tmp_path: Path) -> None:
@@ -552,3 +552,68 @@ def test_a_scan_that_made_no_claims_states_no_limits(tmp_path: Path) -> None:
     write_markdown_report([_finding()], output)
 
     assert "## What was analysed" not in output.read_text()
+
+
+def test_a_model_suspicion_is_grouped_like_a_pattern_match(tmp_path: Path) -> None:
+    """contributor-scan 2.17, Req 5.5's other half.
+
+    A model suspicion is what the enumerator proposed at a site the graph could NOT decide, affirmed by a
+    judge with no coverage there -- a pattern match with an opinion attached. It reads like a reasoned claim
+    because a model produced it, and on vampi it was 38 of 60 findings on a 520-line application.
+    """
+    from dataclasses import replace
+
+    base = _finding()
+    suspicions = [
+        replace(
+            base,
+            finding_id=f"model:injection:api/f{i}.py:{i}:jsonify",
+            evidence_level="suspicion",
+            rung="suspicion",
+            path=f"api/f{i}.py",
+            line=i,
+            rationale="the model resolved no flow here; its sink table may not cover this API",
+        )
+        for i in range(20)
+    ]
+    output = tmp_path / "report.md"
+
+    write_markdown_report(suspicions, output)
+
+    text = output.read_text()
+    assert "`model:injection`" in text, "grouped by family, since the rule is always `model`"
+    assert "20 site(s)" in text
+    assert text.count(f"## {base.title}") == 0
+
+
+def test_an_obligation_finding_is_not_grouped_away(tmp_path: Path) -> None:
+    """It sits at `suspicion` too, but it comes from a structural analysis rather than a guess. Collapsing
+    it would hide a detector -- which an earlier attempt at this rule did, and six tests caught it."""
+    from dataclasses import replace
+
+    base = _finding()
+    obligations = [
+        replace(base, finding_id=f"obligation:protected_read:api/u.py:{i}", evidence_level="suspicion", rung="suspicion", line=i)
+        for i in range(20)
+    ]
+    output = tmp_path / "report.md"
+
+    write_markdown_report(obligations, output)
+
+    assert output.read_text().count(f"## {base.title}") == 20
+
+
+def test_an_entailed_model_finding_keeps_its_section(tmp_path: Path) -> None:
+    """The rung is the product. Whatever the model layer DECIDED is never summarised away."""
+    from dataclasses import replace
+
+    base = _finding()
+    entailed = [
+        replace(base, finding_id=f"model:injection:app.py:{i}:execute", evidence_level="suspicion", rung="model_entailed", line=i)
+        for i in range(20)
+    ]
+    output = tmp_path / "report.md"
+
+    write_markdown_report(entailed, output)
+
+    assert output.read_text().count(f"## {base.title}") == 20