{
  "step": "C388",
  "status": "completed",
  "date": "2026-09-24",
  "title": "Finite E/J strip composition and source boundaries",
  "previous_certificate_sha256": "8364fafc1c302bdb753da1bbfd161ac6c153321ee459ee31e219f917e420ab3e",
  "bindings": {
    "step": "STEP.json",
    "source_manifest": "SOURCE_MANIFEST.json",
    "report": "490d_C388_Finite_E_J_Strip_Composition_and_Source_Boundaries_20260924.md",
    "checkpoint": "490d_Mirror_Checkpoint_After_C388_20260924.md",
    "data": "evidence/DATA.json",
    "results": "evidence/RESULTS.json",
    "calculation": "evidence/CALCULATION.py",
    "verifier": "evidence/check.py",
    "next_step_decision": "NEXT_STEP_DECISION.json",
    "replay": "REPLAY.json",
    "control_integrity": "CONTROL_INTEGRITY.json",
    "readme": "README.md"
  },
  "step_sha256": "43d3415e6dc3cb9722b689744f2c9f89fdc8e664856795f3e507d918de8e019f",
  "source_manifest_sha256": "0dc35ba6d303bd9df0220b4e2de8fa711825d1259fb00eca1d682d6654ad2f65",
  "report_sha256": "eae321e6b3d6e00e3617623115e83e8cccc3c294f4ce825712c2f016e490c3f3",
  "checkpoint_sha256": "d2b933eadbfb107b1f4303d114776e9aba65f7b2e9b91555eccbb8fb6433e4f7",
  "data_sha256": "f0fa378bbf7f5a68728762f5fd7116d8de70744367dc36b34f5cdb2fc4c06e0d",
  "results_sha256": "547970596a1f4a2ea626410e72c27e51bfe8aef3b44c670f9e6d9017a541a42d",
  "calculation_sha256": "fefde6cfa8b75060c57e3f4e2b5ac254ee0788ca1632df58010c453a9485642b",
  "verifier_sha256": "9f175670abb70f7819dd7f6d997ff0bef2e58df8dffd763b433f6c6cd62e332d",
  "next_step_decision_sha256": "69cf7b42391e3276d6ccbf87135b8da008a282621b5f61baa7fcca2d506d5731",
  "replay_sha256": "fd69ab2c3fc26ba466f58fa4e081ed1c114b2021d1b1b5abe8403705d5ac5980",
  "control_integrity_sha256": "9810807cb07b02f43f568f68bb82cb41a6eeff6799902254b4932e5c350ac838",
  "readme_sha256": "f65ea182e1369b2df1864c5b481135b25faeaaeb4e54eede6c0d5dabbb4cac61",
  "assertions_passed": 21,
  "source_checks_passed": 17,
  "main_result": "Two two-edge E/J coordinate strips compose exactly over G1→G2→G3, with four SP/LXX context lifts. Eight bottom P/J words share source endpoints, but only the two JJ routes equal the upper all-J map. Second E images and fourth-Gear MT continuations are absent.",
  "limits": "Composition is finite and context-labelled. A shared source endpoint is not equality of operators, and no new regular Gear, cumulative Gear, endpoint or phase is adopted.",
  "canonical_or_graph_edits": false,
  "new_independent_agent_review": false,
  "review_provenance": "Root-agent analysis and deterministic replay; no new independent-agent review",
  "next_proposed_step": "Reflect the source-qualified E/J square through each of the two already recorded17K corner exchanges and test every resulting point against the frozen cumulative menu. Preserve ancestry phases and distinguish algebraic conjugacy from cumulative source availability.",
  "next_step_executed": false
}