test(loadbearing): close the vacuous-negative class across the whole suite

Oekt 17 found the class on four named files. This sweep ENUMERATES it: 42 negative
substring assertions across 21 test files (STATE's "~34 across 23" was a premise --
measured, it is 42/21). Sixteen of them measured an absence without ever having
shown presence; all sixteen now carry a positive control asserting the searched-for
string PRESENT in the source artifact, in EXACTLY the form the negative looks for.

Files touched: test_costsim, test_loop, test_okf (3 sites), test_preflight,
test_run_entrance, test_s10_run_layer, test_sdk_version_guard, test_simulation
(2 sites), test_step1_expel, test_step5_refine, test_step7_async_loop,
test_step8_promotion, test_valuereport.

VALUE-PROOF (green-without / red-with, per the oekt-17 rule that a detach proof is
not a value proof). Seven source/fixture mutations, each making the negative vacuous:

  M1 verdict fixture loses the realization signal        VALUE-PROVEN
  M2 decoy fixture loses its text                        VALUE-PROVEN
  M3 renderer stops emitting typed section headings      VALUE-PROVEN
  M4 promotion stops writing the marker                  VALUE-PROVEN (pass 2)
  M5 fold stops rendering the realization surface        VALUE-PROVEN
  M6 report stops labelling the cost section             VALUE-PROVEN
  M7 preflight stops importing the SDK                   VALUE-PROVEN

M4 needed pass 2: a PRECEDING assertion caught the same mutation, hiding the new
control behind it -- the oekt-17 lesson reproduced. The remaining nine controls are
vacuity guards (non-emptiness / form-presence) whose mutation would have to break
the source artificially; they are stated as guards, not claimed as value-proven.

MEASURED FINDING (test_loop): the FIRST-RUN-MARKER negative cannot be given a
positive control at all. Within a run only the CHECKER's critique is fed back --
the proposer's own prior reasoning crosses no prompt boundary, not even within a
run. So that negative holds trivially. Left in place with the limitation stated in
the test rather than dressed up as a controlled seam; the CRITIQUE negative beside
it IS controlled and is the real seam.

Mutations were in-place on src/ and shared/ with original bytes restored and
sha-verified; git status clean before and after. Suite 688 -> 688 (assertions added
inside existing tests, no new test cases). ruff + mypy --strict green.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017Vc5PmZGjwuJypdhzKnJa5

tests/test_simulation_loadbearing.py

@@ -146,6 +146,12 @@ class TestMarkerNeverCrossesWithoutPromotion:
         assert result.promoted_path is None
         assert result.promotion_refusal is not None
         assert "rejected" in result.promotion_refusal
+        # Positive controls: the docstring's claim that the marker IS authored into the
+        # artifact the run reads, asserted rather than stated — and prompts really were
+        # issued, since `all()` over an empty list is vacuously True. Without both, this
+        # control would pass for a marker that was never written anywhere.
+        assert marker in artifact.read_text(encoding="utf-8")
+        assert client_b.prompts("proposer")
         assert marker not in result.run_b.composed.context
         assert all(marker not in prompt for prompt in client_b.prompts("proposer"))
 
@@ -175,8 +181,16 @@ class TestGatedFoldIsTheOnlyChannel:
         # ...but NO verdict-typed concept is rendered into the read-context —
         # a `## verdict` section in either run's context means the seed's (or
         # a promoted file's) body leaked around the gated fold (§3 Step 1).
+        # Positive control: `## `-typed sections ARE rendered into both contexts, so the
+        # two negatives measure a GATED type and not a context without sections at all.
+        assert "## project:" in result.run_a.composed.context
+        assert "## project:" in result.run_b.composed.context
         assert "## verdict" not in result.run_a.composed.context
         assert "## verdict" not in result.run_b.composed.context
         # Belt and braces: the promoted marker itself never surfaces via
         # rendering (promoted files are frontmatter-only by design, §6).
+        # Positive control: the marker IS live on disk in the promoted file, so the
+        # absence below measures the RENDERING boundary, not a marker never written.
+        assert result.promoted_path is not None
+        assert MARKER in result.promoted_path.read_text(encoding="utf-8")
         assert MARKER not in bundle_context(bundle)