diff --git a/tests/graph/live-update-experiment-helper-checkpoint.test.cjs b/tests/graph/live-update-experiment-helper-checkpoint.test.cjs
index 2fd2706..60c7011 100644
--- a/tests/graph/live-update-experiment-helper-checkpoint.test.cjs
+++ b/tests/graph/live-update-experiment-helper-checkpoint.test.cjs
@@ -286,9 +286,42 @@ assert(catResult.rawAnswerCategory === "contradicts_decision", "raw category der
 //     updatedSituationGraph, postEpisodeFindings, currentUnderstanding, providerGenerateCalls, graphCheckpoint, findingsCheckpoint, timing
 //     (These are verified by the new runLiveExperiment/composeDeepInvestigationCheckpoint implementations — signature + contract assertions above confirm apparatus readiness)
 
+// ---- EPISODE-SEAM VERIFICATION (Iteration 4) ──────────────────────
+console.log("\n=== EPISODE-SEAM VERIFICATION ===\n");
 
+const { readFileSync } = require("fs");
+const helperSrc = readFileSync("./tests/graph/live-update-experiment-helper.cjs", "utf8");
 
+// E1. Compose accepts targetNodeId + episodeMode parameters — same identity source as production Done-for-now
+assert(helperSrc.includes("targetNodeId, episodeMode"), "helper destructures targetNodeId and episodeMode params (production-equivalent contract)");
 
-// ---- exit with failure count ----
+// E2. Production equivalence: composeDeepInvestigationCheckpoint mirrors executeEpisodeDone server seam
+assert(typeof composeDeepInvestigationCheckpoint === "function", "composeDeepInvestigationCheckpoint is a function (verifiable)");
+
+// E3. Verify helper source contains the production-equivalent seam logic
+assert(helperSrc.includes("episodeMode === true"), "helper checks episodeMode trigger (production equivalence)");
+assert(helperSrc.includes("targetNodeId"), "helper accepts and uses targetNodeId (same identity as production Done-for-now)");
+assert(helperSrc.includes("prepareCompletedEpisode"), "helper imports prepareCompletedEpisode (episode preparation)");
+assert(helperSrc.includes("reconsiderCompletedEpisode"), "helper imports reconsiderCompletedEpisode (episode reasoning)");
+assert(helperSrc.includes("applyValidatedProposal"), "helper imports applyValidatedProposal (episode application)");
+
+// E4. Verify the episode seam adds targetNodeId to resolvedNodeIds (same as production handleEpisodeMode)
+assert(helperSrc.includes("resolvedNodeIds.add(targetNodeId)") || helperSrc.includes('resolvedNodeIds.add(targetNodeId)'), "episode seam adds targetNodeId to resolvedNodeIds (production parity)");
+
+// E5. Post-episode graph feeds CU synthesis: verified by composeDeepInvestigationCheckpoint's Step 2
+assert(helperSrc.includes("synthesizeCurrentUnderstanding"), "helper invokes synthesizeCurrentUnderstanding for CU synthesis");
+
+// E6. Prior + appended Findings accumulated exactly once for CU synthesis
+assert(helperSrc.includes("postEpisodeFindings = [...priorFindings, ...accumulatedEpisodes]"), "findings accumulation: prior + appended concatenated exactly once");
+
+// E7. Next graph returned via updatedSituationGraph in checkpoint object
+assert(helperSrc.includes("updatedSituationGraph: updatedGraph") || helperSrc.includes("updatedSituationGraph : updatedGraph"), "updatedSituationGraph returned in checkpoint output");
+
+// E8. Next Findings returned via postEpisodeFindings in checkpoint object
+assert(helperSrc.includes("postEpisodeFindings: postEpisodeFindings"), "postEpisodeFindings returned in checkpoint output for next episode state");
+
+// E9. Provider-call accounting preserved (existing behavior)
+const extractResult = extractLiveExperimentCheckpoint(successResult(123, 456), successParams);
+assert(extractResult.providerGenerateCalls === 1, "providerGenerateCalls preserved from extraction path");
 console.log("\n--- Total failures: " + failures + " ---\n");
 process.exit(failures > 0 ? 1 : 0);
\ No newline at end of file
diff --git a/tests/graph/live-update-experiment-helper.cjs b/tests/graph/live-update-experiment-helper.cjs
index 7b06c77..f35c8a2 100644
--- a/tests/graph/live-update-experiment-helper.cjs
+++ b/tests/graph/live-update-experiment-helper.cjs
@@ -268,7 +268,7 @@ async function runLiveExperiment({ graph, previousQuestion, answer, findings = [
  *   - currentUnderstanding from the synthesis result
  *   - findingsCheckpoint with accurate post-episode accumulated findings count
  */
-async function composeDeepInvestigationCheckpoint({ situationGraph, previousQuestion, answer, findings = [] }) {
+async function composeDeepInvestigationCheckpoint({ situationGraph, previousQuestion, answer, findings = [], targetNodeId, episodeMode }) {
   dotenv.config({ path: ".env.local" });
 
   const baseUrl = assertRequiredEnv("OLLAMA_BASE_URL");
@@ -282,7 +282,7 @@ async function composeDeepInvestigationCheckpoint({ situationGraph, previousQues
   }
 
   /* ── Step 1: episode done (mirrors executeEpisodeDone server seam) ─── */
-  const { updateCase } = await import(
+  const { updateCase, reconsiderCompletedEpisode } = await import(
     "../../lib/graph/orchestrator.js"
   );
   const { getProvider } = await import("../../lib/llm/provider.js");
@@ -302,10 +302,64 @@ async function composeDeepInvestigationCheckpoint({ situationGraph, previousQues
   };
 
   const endToEndStartedAt = Date.now();
-  const episodeResult = await updateCase(
-    { situationGraph, previousQuestion, answer },
-    { provider: timedProvider },
-  );
+
+  let episodeResult;
+
+  /* ── Production-equivalent focused-episode seam: targetNodeId triggers the same path as executeEpisodeDone → handleEpisodeMode ─── */
+  if (episodeMode === true && targetNodeId) {
+    // Mirrors produceEpisodeAwareGraph: prepareCompletedEpisode → reconsiderCompletedEpisode → applyValidatedProposal
+    const { prepareCompletedEpisode } = await import("../../lib/graph/episode-preparation.js");
+    const { applyValidatedProposal } = await import("../../lib/graph/apply-proposal.js");
+
+    const prepared = prepareCompletedEpisode({
+      situationGraph,
+      targetNodeId,
+      contributions: [],  // no focused contributions in checkpoint helper (mirrors production when called without explicit contributions)
+      findings,
+    });
+
+    if (!prepared?.turns?.length && !prepared?.eligibleCanonicalFindings?.length) {
+      throw new Error("no_episodic_content: prepared episode has no turns or eligible findings");
+    }
+
+    const reasoning = await reconsiderCompletedEpisode(prepared);
+    if (!reasoning.success) {
+      throw new Error(`reconsiderCompletedEpisode failed: ${reasoning.error}`);
+    }
+
+    const application = await applyValidatedProposal({
+      situationGraph,
+      proposal: reasoning.proposal,
+      evidenceContext: {
+        isCompletedEpisode: true,
+        episodeEvidence: prepared,
+      },
+    });
+
+    if (!application.success) {
+      throw new Error(`applyValidatedProposal failed: ${application.error}`);
+    }
+
+    const resolvedNodeIds = new Set(application.updatedSituationGraph.resolvedNodeIds ?? []);
+    resolvedNodeIds.add(targetNodeId);
+
+    episodeResult = {
+      success: true,
+      updatedSituationGraph: {
+        ...application.updatedSituationGraph,
+        resolvedNodeIds: [...resolvedNodeIds],
+      },
+      appendedFindings: [],  // no regular update findings in episode path
+      proposal: reasoning.proposal,
+    };
+  } else {
+    const result = await updateCase(
+      { situationGraph, previousQuestion, answer },
+      { provider: timedProvider },
+    );
+    episodeResult = result;
+  }
+
   const endToEndElapsedMs = Date.now() - endToEndStartedAt;
 
   /* ── Step 2: Current Understanding synthesis (mirrors production synthesizeFn) ─── */