docs(confidence-engine): record product-launch epistemic A/B result — 4-iteration loop complete

Controlled A/B (zero-Findings scenario, Qwen): unresolved uncertainty exposure
did not contaminate supported understanding or plausible interpretation.
No production changes. No report semantic changes.

docs/current-handoff.md

@@ -309,7 +309,22 @@ scripts/overview-experiment-helper.cjs       — canonical overview live helper
   - **visible**: appends unresolved questions as separate NON-EVIDENCE section to baseline prompt
 - Apparatus invariant proven deterministically: A/B evidence, findings, plausibleInterpretations, scenario state are identical; only unresolved visibility differs.
 - Production `lib/graph/investigation-overview-synthesis.js` unchanged.
-- **No live A/B calls executed yet.** Next boundary: Call A (hidden) with product-launch fixture.
+- **Controlled A/B completed:** product-launch zero-Findings case, 2 live calls (51s hidden, 54s visible).
+
+**Result:** Supported understanding materially unchanged; both calls produce the same core finding (product ready enough for launch, one large enterprise client relevant). No plausible interpretations in either variant (helper called with `[]` plausibleInterpretations — correct for this fixture's initial state). Unresolved customer-signing and competitor uncertainty remained distinct, unanswered, non-evidence in B. Neither call promoted unresolved material into supported understanding or plausible interpretation.
+
+**Contamination classification:** NONE
+- No supported claim added or removed
+- No qualification/certainty shift beyond minor phrasing variation (~17 chars)
+- Customer-signing uncertainty: NOT promoted to evidence, NOT interpreted/answered
+- Competitor uncertainty: NOT promoted to evidence, NOT interpreted/answered
+- Unresolved not prioritised in either call
+
+**What this establishes:** Under controlled product-launch conditions (zero Findings), exposing unresolved future-dependent Open Questions as a separate NON-EVIDENCE section does not cause the model to use that uncertainty as evidence or merge it into plausible interpretation. The epistemic boundary holds for Qwen under this scenario shape.
+
+**What it does not establish:** Does not prove universality across other scenarios, other models, or when plausibleInterpretations are non-empty. Does not generalize to manufacturing scenarios (with findings). One scenario shape only.
+
+### Zero-Finding Report Experiment Case (Loop 2/3)
 
 ### Zero-Finding Report Experiment Case (Loop 2/3)