diff --git a/src/application/investigation/EvidenceLedger.ts b/src/application/investigation/EvidenceLedger.ts
index 5a83f8c718..a8fc6da9b6 100644
--- a/src/application/investigation/EvidenceLedger.ts
+++ b/src/application/investigation/EvidenceLedger.ts
@@ -4,14 +4,16 @@ import { z } from "zod";
 import {
   createEvidenceBundle,
   createImmutableEvidenceBundle,
-  safeParseEvidenceBundle,
+  safeParseImmutableEvidenceBundle,
+  InvalidResidualUnknownGraphError,
   validateResidualUnknownAddition,
   type EvidenceBundle,
 } from "../../domain/evidenceBundle.js";
 import { AnalysisInputError } from "../../domain/analysisErrorCore.js";
 import { EvidenceIntegrityError } from "../../domain/evidenceErrors.js";
 import { UnknownRegistryError } from "../../domain/unknownRegistryError.js";
-import { immutableEvidence, type Evidence } from "../../domain/evidence.js";
+import type { Evidence } from "../../domain/evidence.js";
+import { readImmutableEvidence } from "../../domain/evidenceValidation.js";
 import {
   createResidualUnknown,
   updateResidualUnknown,
@@ -43,21 +45,17 @@ type ImportResult = Result<
 
 /** Session-owned set of immutable evidence records. */
 export class EvidenceLedger {
-  readonly #records = new Map<string, Evidence>();
-  readonly #unknownRevisions = new Map<string, ResidualUnknown>();
-  readonly #unknownHeads = new Map<string, ResidualUnknown>();
+  #records = new Map<string, Evidence>();
+  #unknownRevisions = new Map<string, ResidualUnknown>();
+  #unknownHeads = new Map<string, ResidualUnknown>();
   /** Record evidence idempotently; conflicting content is rejected. */
   record(input: Evidence): RecordResult {
-    let evidence: Evidence;
-    try {
-      evidence = immutableEvidence(input);
-    } catch (cause: unknown) {
-      return err(
-        new EvidenceIntegrityError("Evidence record validation failed", {
-          cause,
-        }),
-      );
-    }
+    const authenticated = readLedgerEvidence(
+      input,
+      "Evidence record validation failed",
+    );
+    if (!authenticated.ok) return authenticated;
+    const evidence = authenticated.value;
     const existing = this.#records.get(evidence.evidence_id);
     if (existing !== undefined) {
       // A borrowed record is already authenticated and deeply immutable. Its
@@ -74,7 +72,7 @@ export class EvidenceLedger {
 
   /** Validate an entire bundle before atomically merging its records. */
   import(input: unknown): ImportResult {
-    const parsed = safeParseEvidenceBundle(input);
+    const parsed = safeParseImmutableEvidenceBundle(input);
     if (!parsed.ok) {
       const { kind, message, cause } = parsed.error;
       if (kind === "single-record")
@@ -116,9 +114,8 @@ export class EvidenceLedger {
         additions.set(evidence.evidence_id, evidence);
       }
       for (const [id, evidence] of replacements)
-        this.#records.set(id, immutableEvidence(evidence));
-      for (const [id, evidence] of additions)
-        this.#records.set(id, immutableEvidence(evidence));
+        this.#records.set(id, evidence);
+      for (const [id, evidence] of additions) this.#records.set(id, evidence);
       return ok({
         recordsAdded: additions.size,
         unknownsAdded: 0,
@@ -154,19 +151,14 @@ export class EvidenceLedger {
     }
     const checked = this.#validateCandidate(pending, pendingUnknowns);
     if (!checked.ok) {
-      if (checked.error instanceof UnknownRegistryError)
-        return err(
-          new EvidenceIntegrityError(
-            "Evidence bundle unknown registry failed",
-            {
-              cause: checked.error,
-            },
-          ),
-        );
-      return err(checked.error);
+      return err(
+        new EvidenceIntegrityError("Evidence bundle unknown registry failed", {
+          cause: checked.error,
+        }),
+      );
     }
     const added = pending.size - this.#records.size;
-    this.#commit(pending, pendingUnknowns);
+    this.#commit(checked.value);
     return ok({
       recordsAdded: added,
       unknownsAdded,
@@ -217,16 +209,12 @@ export class EvidenceLedger {
     ResidualUnknown,
     EvidenceIntegrityError | UnknownRegistryError | AnalysisInputError
   > {
-    let parsedMutation: Evidence;
-    try {
-      parsedMutation = immutableEvidence(mutationEvidence);
-    } catch (cause: unknown) {
-      return err(
-        new EvidenceIntegrityError("Unknown mutation evidence is invalid", {
-          cause,
-        }),
-      );
-    }
+    const authenticated = readLedgerEvidence(
+      mutationEvidence,
+      "Unknown mutation evidence is invalid",
+    );
+    if (!authenticated.ok) return authenticated;
+    const parsedMutation = authenticated.value;
     let unknown: ResidualUnknown;
     try {
       unknown = createResidualUnknown(
@@ -235,7 +223,8 @@ export class EvidenceLedger {
         parsedMutation.subject?.digest.sha256 ?? null,
       );
     } catch (cause: unknown) {
-      return err(unknownInputError("record_unknown", cause, input));
+      if (!(cause instanceof z.ZodError)) throw cause;
+      return err(requestInputError("record_unknown", cause, input));
     }
     if (this.#unknownHeads.has(unknown.unknown_id))
       return err(new UnknownRegistryError("already-exists"));
@@ -251,18 +240,18 @@ export class EvidenceLedger {
     ResidualUnknown | null,
     EvidenceIntegrityError | UnknownRegistryError
   > {
-    let evidence: Evidence;
-    let mutation: Evidence;
-    try {
-      evidence = immutableEvidence(evidenceInput);
-      mutation = immutableEvidence(mutationInput);
-    } catch (cause: unknown) {
-      return err(
-        new EvidenceIntegrityError("Atomic Evidence validation failed", {
-          cause,
-        }),
-      );
-    }
+    const authenticatedEvidence = readLedgerEvidence(
+      evidenceInput,
+      "Atomic Evidence validation failed",
+    );
+    if (!authenticatedEvidence.ok) return authenticatedEvidence;
+    const authenticatedMutation = readLedgerEvidence(
+      mutationInput,
+      "Atomic Evidence validation failed",
+    );
+    if (!authenticatedMutation.ok) return authenticatedMutation;
+    const evidence = authenticatedEvidence.value;
+    const mutation = authenticatedMutation.value;
     const existingEvidence = this.#records.get(evidence.evidence_id);
     if (
       existingEvidence !== undefined &&
@@ -277,6 +266,7 @@ export class EvidenceLedger {
         mutation.subject?.digest.sha256 ?? null,
       );
     } catch (cause: unknown) {
+      if (!(cause instanceof z.ZodError)) throw cause;
       return err(new UnknownRegistryError("invalid-transition", { cause }));
     }
     const creationUnknown = this.#unknownRevisions.get(
@@ -315,9 +305,15 @@ export class EvidenceLedger {
         mutationEvidence.evidence_id,
       );
     } catch (cause: unknown) {
-      return err(unknownInputError("update_unknown", cause, input));
+      if (!(cause instanceof z.ZodError)) throw cause;
+      return err(requestInputError("update_unknown", cause, input));
     }
-    return this.#appendUnknown(unknown, mutationEvidence);
+    const authenticated = readLedgerEvidence(
+      mutationEvidence,
+      "Unknown mutation evidence is invalid",
+    );
+    if (!authenticated.ok) return authenticated;
+    return this.#appendUnknown(unknown, authenticated.value);
   }
 
   /** Query current heads in stable ID order. */
@@ -391,23 +387,14 @@ export class EvidenceLedger {
 
   #appendUnknown(
     unknown: ResidualUnknown,
-    mutationEvidenceInput: Evidence,
+    mutationEvidence: Evidence,
   ): Result<ResidualUnknown, EvidenceIntegrityError | UnknownRegistryError> {
-    let mutationEvidence: Evidence;
-    try {
-      mutationEvidence = immutableEvidence(mutationEvidenceInput);
-    } catch (cause: unknown) {
-      return err(
-        new EvidenceIntegrityError("Unknown mutation evidence is invalid", {
-          cause,
-        }),
-      );
-    }
     const checked = this.#appendIncremental([mutationEvidence], unknown);
     if (!checked.ok) return checked;
     return ok(structuredClone(unknown));
   }
 
+  /** Incoming records were authenticated and sealed at the ingestion boundary. */
   #appendIncremental(
     records: readonly Evidence[],
     unknown?: ResidualUnknown,
@@ -439,10 +426,10 @@ export class EvidenceLedger {
           this.#unknownHeads,
         );
       } catch (cause: unknown) {
+        if (!(cause instanceof InvalidResidualUnknownGraphError)) throw cause;
         return err(new UnknownRegistryError("integrity", { cause }));
       }
-    for (const [id, evidence] of additions)
-      this.#records.set(id, immutableEvidence(evidence));
+    for (const [id, evidence] of additions) this.#records.set(id, evidence);
     if (unknown !== undefined && unknownKey !== undefined) {
       this.#unknownRevisions.set(unknownKey, unknown);
       this.#unknownHeads.set(unknown.unknown_id, unknown);
@@ -450,48 +437,60 @@ export class EvidenceLedger {
     return ok(undefined);
   }
 
+  /** Return the sealed candidate facts that the commit will adopt. */
   #validateCandidate(
     records: ReadonlyMap<string, Evidence>,
     unknowns: ReadonlyMap<string, ResidualUnknown>,
-  ): Result<void, EvidenceIntegrityError | UnknownRegistryError> {
+  ): Result<EvidenceBundle, UnknownRegistryError> {
     try {
-      createImmutableEvidenceBundle(
-        [...records.values()],
-        [...unknowns.values()],
+      return ok(
+        createImmutableEvidenceBundle(
+          [...records.values()],
+          [...unknowns.values()],
+        ),
       );
     } catch (cause: unknown) {
+      if (
+        !(cause instanceof z.ZodError) &&
+        !(cause instanceof InvalidResidualUnknownGraphError)
+      )
+        throw cause;
       return err(new UnknownRegistryError("integrity", { cause }));
     }
-    return ok(undefined);
   }
 
-  #commit(
-    records: ReadonlyMap<string, Evidence>,
-    unknowns: ReadonlyMap<string, ResidualUnknown>,
-  ): void {
-    this.#records.clear();
-    for (const [id, evidence] of records)
-      this.#records.set(id, immutableEvidence(evidence));
-    this.#unknownRevisions.clear();
-    this.#unknownHeads.clear();
-    for (const [key, unknown] of unknowns) {
-      this.#unknownRevisions.set(key, unknown);
-      const head = this.#unknownHeads.get(unknown.unknown_id);
+  #commit(bundle: EvidenceBundle): void {
+    const records = new Map(
+      bundle.records.map((evidence) => [evidence.evidence_id, evidence]),
+    );
+    const unknownRevisions = new Map(
+      bundle.unknowns.map((unknown) => [unknownRevisionKey(unknown), unknown]),
+    );
+    const unknownHeads = new Map<string, ResidualUnknown>();
+    for (const unknown of bundle.unknowns) {
+      const head = unknownHeads.get(unknown.unknown_id);
       if (head === undefined || head.revision < unknown.revision)
-        this.#unknownHeads.set(unknown.unknown_id, unknown);
+        unknownHeads.set(unknown.unknown_id, unknown);
     }
+    this.#records = records;
+    this.#unknownRevisions = unknownRevisions;
+    this.#unknownHeads = unknownHeads;
   }
 }
 
-/** A caller's unknown that fails its schema is an input mistake, not a state change. */
-const unknownInputError = (
-  operation: "record_unknown" | "update_unknown",
-  cause: unknown,
-  input: RecordUnknownInput | UpdateUnknownInput,
-): UnknownRegistryError | AnalysisInputError =>
-  cause instanceof z.ZodError
-    ? requestInputError(operation, cause, input)
-    : new UnknownRegistryError("invalid-transition", { cause });
+const readLedgerEvidence = (
+  input: unknown,
+  message: string,
+): Result<Evidence, EvidenceIntegrityError> => {
+  const checked = readImmutableEvidence(input);
+  return checked.ok
+    ? checked
+    : err(
+        new EvidenceIntegrityError(message, {
+          cause: checked.error.cause,
+        }),
+      );
+};
 
 const unknownRevisionKey = (unknown: ResidualUnknown): string =>
   `${unknown.unknown_id}:${String(unknown.revision)}`;
diff --git a/tests/process-global/ledgerMutationFailures.test.ts b/tests/process-global/ledgerMutationFailures.test.ts
new file mode 100644
index 0000000000..15d01321b1
--- /dev/null
+++ b/tests/process-global/ledgerMutationFailures.test.ts
@@ -0,0 +1,311 @@
+import { expect, it, onTestFinished, vi } from "vitest";
+
+import * as evidenceDomain from "../../src/domain/evidence.js";
+import * as evidenceBundleDomain from "../../src/domain/evidenceBundle.js";
+import * as residualUnknownDomain from "../../src/domain/residualUnknown.js";
+import {
+  recordUnknownInputSchema,
+  updateUnknownInputSchema,
+} from "../../src/domain/residualUnknown.js";
+import { processEvidence } from "../../src/application/ReconstructionObligationLedger.fixture.js";
+import { createApplicationMcpHarness } from "../fixtures/applicationMcpHarness.js";
+import { createTestBinarySession } from "../fixtures/binarySession.js";
+import { InvestigationRecords } from "../../src/application/investigation/InvestigationRecords.js";
+
+type ApplicationClient = Awaited<
+  ReturnType<typeof createApplicationMcpHarness>
+>["client"];
+
+const unknownInput = (question: string) =>
+  recordUnknownInputSchema.parse({
+    question,
+    domain: "ledger-failure",
+    severity: "medium",
+    required_authority: "analyst-inference",
+    required_confidence: "observed",
+    required_environment: null,
+    recommended_probes: [],
+    relationships: [],
+    supporting_evidence_ids: [],
+    contradicting_evidence_ids: [],
+  });
+
+const updateInput = (unknownId: string, expectedRevision: number) =>
+  updateUnknownInputSchema.parse({
+    unknown_id: unknownId,
+    expected_revision: expectedRevision,
+    status: "investigating",
+    severity: "medium",
+    supporting_evidence_ids: [],
+    contradicting_evidence_ids: [],
+    required_authority: "analyst-inference",
+    required_confidence: "observed",
+    required_environment: null,
+    recommended_probes: [],
+    relationships: [],
+    resolution: null,
+  });
+
+const failureFor = (kind: "TypeError" | "Error", message: string): Error =>
+  kind === "TypeError" ? new TypeError(message) : new Error(message);
+
+const expectSdkFailure = async (
+  client: ApplicationClient,
+  name: "record_unknown" | "update_unknown",
+  args: Record<string, unknown>,
+  failure: Error,
+): Promise<void> => {
+  const response = await client.callTool({
+    name,
+    arguments: args,
+  });
+  expect(response).toMatchObject({
+    isError: true,
+    content: [{ type: "text", text: failure.message }],
+  });
+  expect(response.structuredContent).toBeUndefined();
+};
+
+const withHarness = async <T>(
+  run: (
+    harness: Awaited<ReturnType<typeof createApplicationMcpHarness>>,
+  ) => Promise<T>,
+): Promise<T> => {
+  const session = createTestBinarySession(() => {
+    throw new Error("Ledger mutations must not launch a provider");
+  });
+  const harness = await createApplicationMcpHarness({ session });
+  try {
+    return await run(harness);
+  } finally {
+    vi.restoreAllMocks();
+    await harness.close();
+  }
+};
+
+it.each(
+  (["recordEvidence", "recordEvidenceWithUnknown"] as const).flatMap(
+    (operation) =>
+      (["TypeError", "Error"] as const).map(
+        (kind) => [operation, kind] as const,
+      ),
+  ),
+)(
+  "lets unexpected authentication failure escape %s (%s) without changing the bundle",
+  async (operation, kind) =>
+    withHarness(async ({ session }) => {
+      const derived = processEvidence();
+      const input = unknownInput(`Failure during ${operation}`);
+      const before = session.exportEvidenceBundle();
+      const failure = failureFor(kind, `${operation} authentication failed`);
+      const authenticate = vi
+        .spyOn(evidenceDomain, "immutableEvidence")
+        .mockImplementation(() => {
+          throw failure;
+        });
+      onTestFinished(() => authenticate.mockRestore());
+
+      if (operation === "recordEvidence")
+        expect(() => session.recordEvidence(derived)).toThrow(failure);
+      else
+        expect(() => session.recordEvidenceWithUnknown(derived, input)).toThrow(
+          failure,
+        );
+      expect(session.exportEvidenceBundle()).toEqual(before);
+    }),
+);
+
+it("preserves an unexpected unknown-construction fault through record_unknown", async () =>
+  withHarness(async ({ client, session }) => {
+    const before = session.exportEvidenceBundle();
+    const failure = new TypeError("unknown constructor implementation failed");
+    const construct = vi
+      .spyOn(residualUnknownDomain, "createResidualUnknown")
+      .mockImplementation(() => {
+        throw failure;
+      });
+    onTestFinished(() => construct.mockRestore());
+
+    await expectSdkFailure(
+      client,
+      "record_unknown",
+      unknownInput("Unexpected constructor failure"),
+      failure,
+    );
+    expect(session.exportEvidenceBundle()).toEqual(before);
+  }));
+
+it("preserves an unexpected unknown-revision fault through update_unknown", async () =>
+  withHarness(async ({ client, session }) => {
+    const created = session.recordUnknown(unknownInput("Update failure setup"));
+    if (!created.ok) throw created.error;
+    const before = session.exportEvidenceBundle();
+    const failure = new Error("unknown update implementation failed");
+    const update = vi
+      .spyOn(residualUnknownDomain, "updateResidualUnknown")
+      .mockImplementation(() => {
+        throw failure;
+      });
+    onTestFinished(() => update.mockRestore());
+
+    await expectSdkFailure(
+      client,
+      "update_unknown",
+      updateInput(created.value.unknown_id, created.value.revision),
+      failure,
+    );
+    expect(session.exportEvidenceBundle()).toEqual(before);
+  }));
+
+it.each(
+  (["record_unknown", "update_unknown"] as const).flatMap((operation) =>
+    (["TypeError", "Error"] as const).map((kind) => [operation, kind] as const),
+  ),
+)(
+  "preserves unexpected mutation Evidence authentication failure through %s (%s)",
+  async (operation, kind) =>
+    withHarness(async ({ client, session }) => {
+      let args: Record<string, unknown>;
+      if (operation === "record_unknown") {
+        args = unknownInput("Mutation Evidence authentication failure");
+      } else {
+        const created = session.recordUnknown(
+          unknownInput("Mutation Evidence authentication setup"),
+        );
+        if (!created.ok) throw created.error;
+        args = updateInput(created.value.unknown_id, created.value.revision);
+      }
+      const before = session.exportEvidenceBundle();
+      const failure = failureFor(
+        kind,
+        "mutation Evidence authentication failed",
+      );
+      const authenticate = vi
+        .spyOn(evidenceDomain, "immutableEvidence")
+        .mockImplementation(() => {
+          throw failure;
+        });
+      onTestFinished(() => authenticate.mockRestore());
+
+      await expectSdkFailure(client, operation, args, failure);
+      expect(session.exportEvidenceBundle()).toEqual(before);
+    }),
+);
+
+it.each([
+  ["record_unknown", "record graph failure"],
+  ["update_unknown", "update graph failure"],
+] as const)(
+  "does not convert an unexpected graph-validation fault during %s into a caller error",
+  async (operation, message) =>
+    withHarness(async ({ client, session }) => {
+      let args: Record<string, unknown>;
+      if (operation === "record_unknown") {
+        args = unknownInput(`Unexpected graph validation: ${message}`);
+      } else {
+        const created = session.recordUnknown(
+          unknownInput(`Graph validation setup: ${message}`),
+        );
+        if (!created.ok) throw created.error;
+        args = updateInput(created.value.unknown_id, created.value.revision);
+      }
+      const before = session.exportEvidenceBundle();
+      const failure = new Error(message);
+      const validate = vi
+        .spyOn(evidenceBundleDomain, "validateResidualUnknownAddition")
+        .mockImplementation(() => {
+          throw failure;
+        });
+      onTestFinished(() => validate.mockRestore());
+
+      await expectSdkFailure(client, operation, args, failure);
+      expect(session.exportEvidenceBundle()).toEqual(before);
+    }),
+);
+
+it("preserves unexpected full-candidate bundle validation faults and leaves import state unchanged", async () =>
+  withHarness(async ({ session }) => {
+    const source = new InvestigationRecords();
+    const created = source.recordUnknown(unknownInput("Imported history"));
+    if (!created.ok) throw created.error;
+    const bundle = source.exportEvidenceBundle();
+    const before = session.exportEvidenceBundle();
+    const failure = new TypeError("candidate bundle validation failed");
+    const validate = vi
+      .spyOn(evidenceBundleDomain, "createImmutableEvidenceBundle")
+      .mockImplementation(() => {
+        throw failure;
+      });
+    onTestFinished(() => validate.mockRestore());
+
+    expect(() => session.importEvidenceBundle(bundle)).toThrow(failure);
+    expect(session.exportEvidenceBundle()).toEqual(before);
+  }));
+
+it("authenticates derived and mutation Evidence before committing recordWithUnknown", async () =>
+  withHarness(async ({ session }) => {
+    const input = unknownInput("Atomic record with unknown");
+    const evidence = processEvidence();
+    const expectedId = evidence.evidence_id;
+    const original = evidenceDomain.immutableEvidence;
+    let evidenceVisibleDuringAuthentication = false;
+    const authenticate = vi
+      .spyOn(evidenceDomain, "immutableEvidence")
+      .mockImplementation((candidate) => {
+        if (
+          session
+            .exportEvidenceBundle()
+            .records.some((record) => record.evidence_id === expectedId)
+        )
+          evidenceVisibleDuringAuthentication = true;
+        return original(candidate);
+      });
+    onTestFinished(() => authenticate.mockRestore());
+
+    const recorded = session.recordEvidenceWithUnknown(evidence, input);
+    authenticate.mockRestore();
+    expect(recorded.ok).toBe(true);
+    expect(evidenceVisibleDuringAuthentication).toBe(false);
+    const committed = session.exportEvidenceBundle();
+    expect(committed.records.map(({ evidence_id }) => evidence_id)).toContain(
+      expectedId,
+    );
+    expect(committed.unknowns).toHaveLength(1);
+    expect(committed.records).toHaveLength(2);
+    expect(
+      session.immutableEvidenceBundle().records.every(Object.isFrozen),
+    ).toBe(true);
+  }));
+
+it("authenticates all Evidence before committing an imported unknown history", async () =>
+  withHarness(async ({ session }) => {
+    const source = new InvestigationRecords();
+    expect(source.recordEvidence(processEvidence()).ok).toBe(true);
+    const created = source.recordUnknown(
+      unknownInput("Atomic imported history"),
+    );
+    if (!created.ok) throw created.error;
+    const bundle = source.exportEvidenceBundle();
+    const expectedIds = bundle.records.map(({ evidence_id }) => evidence_id);
+    const original = evidenceDomain.immutableEvidence;
+    let incomingVisibleDuringAuthentication = false;
+    const authenticate = vi
+      .spyOn(evidenceDomain, "immutableEvidence")
+      .mockImplementation((input) => {
+        const visible = session
+          .exportEvidenceBundle()
+          .records.some(({ evidence_id }) => expectedIds.includes(evidence_id));
+        if (visible) incomingVisibleDuringAuthentication = true;
+        return original(input);
+      });
+    onTestFinished(() => authenticate.mockRestore());
+
+    const imported = session.importEvidenceBundle(bundle);
+    authenticate.mockRestore();
+    expect(imported.ok).toBe(true);
+    expect(incomingVisibleDuringAuthentication).toBe(false);
+    expect(session.exportEvidenceBundle()).toEqual(bundle);
+    expect(
+      session.immutableEvidenceBundle().records.every(Object.isFrozen),
+    ).toBe(true);
+  }));