diff --git a/src/application/binary/AnalysisSnapshotFiles.ts b/src/application/binary/AnalysisSnapshotFiles.ts
index 5b98f65439..3c22a1831b 100644
--- a/src/application/binary/AnalysisSnapshotFiles.ts
+++ b/src/application/binary/AnalysisSnapshotFiles.ts
@@ -14,6 +14,7 @@ import {
 } from "../../domain/evidenceErrors.js";
 import { err, ok, type Result } from "../../domain/result.js";
 import { describeValidationFailure } from "../../domain/validationFailure.js";
+import { validationIssueOptions } from "../../domain/evidenceValidation.js";
 import { isUnsupportedEvidenceFormat } from "../../domain/evidenceFormat.js";
 import type { AnalysisResourceConstraintError } from "../../domain/analysisErrorCore.js";
 import {
@@ -87,7 +88,10 @@ export const readAnalysisSnapshot = async (
     if (signal?.aborted === true)
       return err(cancelledBy(READ_OPERATION, signal));
     return err(
-      new EvidenceIntegrityError(snapshotValidationMessage(cause), { cause }),
+      new EvidenceIntegrityError(snapshotValidationMessage(cause), {
+        cause,
+        ...validationIssueOptions(cause, []),
+      }),
     );
   }
 };
@@ -156,7 +160,10 @@ export const writeAnalysisSnapshot = async (
     encoded = serializeAnalysisSnapshot(snapshot);
   } catch (cause: unknown) {
     return err(
-      new EvidenceIntegrityError(snapshotValidationMessage(cause), { cause }),
+      new EvidenceIntegrityError(snapshotValidationMessage(cause), {
+        cause,
+        ...validationIssueOptions(cause, []),
+      }),
     );
   }
   return writeTextFile(encoded, path, overwrite, resources);
diff --git a/src/application/process/ProcessCli.ts b/src/application/process/ProcessCli.ts
index 5eecd16da1..e3ebb07cad 100644
--- a/src/application/process/ProcessCli.ts
+++ b/src/application/process/ProcessCli.ts
@@ -14,7 +14,7 @@ import type { AnalysisErrorProjection } from "../../domain/analysisErrorProjecti
 import { ProviderAdapterError } from "../../domain/providerAdapterError.js";
 import {
   describeValidationFailure,
-  firstValidationIssuePath,
+  firstValidationIssue,
 } from "../../domain/validationFailure.js";
 import { PROCESS_PROVIDER } from "../../domain/process/processEvidenceProvider.js";
 import {
@@ -35,6 +35,7 @@ import { ProcessCaptureError } from "../../process/capture/ProcessCaptureError.j
 import {
   createProcessCaptureEvidence,
   createProcessScenarioPlanEvidence,
+  wrongWorkflowIssueFacts,
   type ProcessCaptureEvidenceFailure,
 } from "./ProcessEvidence.js";
 import { prepareProcessScenarioPlan } from "./ProcessScenarioPreparation.js";
@@ -282,6 +283,7 @@ const projectCaptureFileFailure = (
         "Capture evidence is not from the current process-capture workflow. Create new capture evidence, then try again.",
         [side],
         "invalid_value",
+        wrongWorkflowIssueFacts(failure),
       );
     case "unsupported-provider":
       return unsupportedProcessCaptureProvider(side, failure);
@@ -305,15 +307,23 @@ const parseTraceSpecification = (input: unknown) => {
 };
 
 const invalidCaptureEvidence = (cause: unknown, side: "left" | "right") => {
-  const issuePath = firstValidationIssuePath(cause);
+  const issue = firstValidationIssue(cause);
   return processInputFailure(
     "compare_process_captures",
     `Capture evidence is malformed (${describeValidationFailure(cause)}). Create new capture evidence, then try again.`,
     [side],
     "invalid_value",
-    issuePath === undefined
+    issue === undefined
       ? undefined
-      : { issue_path: ["normalized_result", ...issuePath] },
+      : {
+          observed: {
+            issue_path: ["normalized_result", ...issue.path],
+            ...(issue.constraint === undefined
+              ? {}
+              : { constraint: issue.constraint }),
+            remaining_issue_count: issue.remainingIssueCount,
+          },
+        },
   );
 };
 
@@ -344,7 +354,7 @@ const readJson = async (
     ["input_file"],
     "invalid_value",
     // Read and parse failures share one issue reason; name which one occurred.
-    { file_reason: loaded.error.reason },
+    { observed: { file_reason: loaded.error.reason } },
   );
 };
 
@@ -353,15 +363,10 @@ const processInputFailure = (
   userMessage: string,
   path: readonly (string | number)[],
   reason: "invalid_value" | "missing_argument",
-  observed?: AnalysisInputIssue["observed"],
+  facts?: Pick<AnalysisInputIssue, "expected" | "observed">,
 ): AnalysisInputError =>
   new AnalysisInputError(operation, { userMessage }, [
-    {
-      path,
-      reason,
-      message: userMessage,
-      ...(observed === undefined ? {} : { observed }),
-    },
+    { path, reason, message: userMessage, ...facts },
   ]);
 
 const cliAnalysisError = (error: AnalysisError): ProcessCliErrorOutput => ({
diff --git a/src/application/process/ProcessComparisonService.ts b/src/application/process/ProcessComparisonService.ts
index 29c82ef352..f109a92e63 100644
--- a/src/application/process/ProcessComparisonService.ts
+++ b/src/application/process/ProcessComparisonService.ts
@@ -1,11 +1,9 @@
 import { processComparisonInputSchema } from "../../contracts/processComparisonContracts.js";
 import { AnalysisError } from "../../domain/analysisErrorBase.js";
 import { AnalysisInputError } from "../../domain/analysisErrorCore.js";
-import {
-  describeValidationFailure,
-  firstValidationIssuePath,
-} from "../../domain/validationFailure.js";
+import { describeValidationFailure } from "../../domain/validationFailure.js";
 import { EvidenceIntegrityError } from "../../domain/evidenceErrors.js";
+import { validationIssueOptions } from "../../domain/evidenceValidation.js";
 import {
   PROCESS_COMPARISON_DIMENSIONS,
   type ProcessCaptureComparison,
@@ -19,6 +17,7 @@ import type { RecordUnknownInput } from "../../domain/residualUnknown.js";
 import { err, ok, type Result } from "../../domain/result.js";
 import {
   parseProcessCaptureEvidence,
+  wrongWorkflowIssueFacts,
   type ProcessCaptureEvidenceFailure,
 } from "./ProcessEvidence.js";
 import {
@@ -114,7 +113,7 @@ export const readProcessComparisonSource = (
         new EvidenceIntegrityError(`${side} Evidence failed validation`, {
           cause: failure.cause,
           side,
-          ...issuePathFact(failure.cause),
+          ...validationIssueOptions(failure.cause, []),
           userMessage: `The ${side} Evidence failed validation (${describeValidationFailure(failure.cause)}). Supply unmodified capture Evidence from capture_process_scenario.`,
         }),
       );
@@ -125,6 +124,7 @@ export const readProcessComparisonSource = (
             path: [side],
             reason: "invalid_value",
             message: `Expected process capture Evidence (operation ${failure.expected.operation}, predicate ${failure.expected.predicate}); the ${side} Evidence has operation ${failure.actual.operation} and predicate ${failure.actual.predicate}.`,
+            ...wrongWorkflowIssueFacts(failure),
           },
         ]),
       );
@@ -137,7 +137,7 @@ export const readProcessComparisonSource = (
           {
             cause: failure.cause,
             side,
-            ...issuePathFact(failure.cause, ["normalized_result"]),
+            ...validationIssueOptions(failure.cause, ["normalized_result"]),
             userMessage: `The ${side} Evidence has an invalid process capture result (${describeValidationFailure(failure.cause)}). Recreate the capture with capture_process_scenario.`,
           },
         ),
@@ -145,17 +145,6 @@ export const readProcessComparisonSource = (
   }
 };
 
-/** Issue paths are relative to the Evidence record, as for `readEvidence`. */
-const issuePathFact = (
-  cause: unknown,
-  within: readonly (string | number)[] = [],
-) => {
-  const issuePath = firstValidationIssuePath(cause);
-  return issuePath === undefined
-    ? {}
-    : { issuePath: [...within, ...issuePath] };
-};
-
 /** Report the same provider admission failure at both public adapters. */
 export const unsupportedProcessCaptureProvider = (
   side: "left" | "right",
diff --git a/src/application/process/ProcessEvidence.ts b/src/application/process/ProcessEvidence.ts
index bd21493d42..ec3361872c 100644
--- a/src/application/process/ProcessEvidence.ts
+++ b/src/application/process/ProcessEvidence.ts
@@ -50,6 +50,20 @@ export type ProcessCaptureEvidenceFailure =
     }
   | { readonly kind: "invalid-capture"; readonly cause: z.ZodError };
 
+/** The workflow a capture input must come from and the one it came from, as input-issue facts. */
+export const wrongWorkflowIssueFacts = (
+  failure: Extract<ProcessCaptureEvidenceFailure, { kind: "wrong-workflow" }>,
+) => ({
+  expected: {
+    operation: failure.expected.operation,
+    predicate_type: failure.expected.predicate,
+  },
+  observed: {
+    operation: failure.actual.operation,
+    predicate_type: failure.actual.predicate,
+  },
+});
+
 /** Authenticate capture Evidence before admitting its workflow, provider and payload. */
 export const parseProcessCaptureEvidence = (
   input: unknown,
diff --git a/src/domain/analysisErrorProjection.ts b/src/domain/analysisErrorProjection.ts
index 8bcc3e3169..3bbeb77790 100644
--- a/src/domain/analysisErrorProjection.ts
+++ b/src/domain/analysisErrorProjection.ts
@@ -804,6 +804,12 @@ const requestErrorDetails = (
       ...(error.issuePath === undefined
         ? {}
         : { issue_path: [...error.issuePath] }),
+      ...(error.constraint === undefined
+        ? {}
+        : { constraint: error.constraint }),
+      ...(error.remainingIssueCount === undefined
+        ? {}
+        : { remaining_issue_count: error.remainingIssueCount }),
     };
   return undefined;
 };
diff --git a/src/domain/analysisSnapshot.ts b/src/domain/analysisSnapshot.ts
index 91c24cfe8a..2b6699908e 100644
--- a/src/domain/analysisSnapshot.ts
+++ b/src/domain/analysisSnapshot.ts
@@ -277,6 +277,27 @@ const snapshotFileHeaderSchema = z.object({
   evidence_bundle: z.unknown(),
 });
 
+/**
+ * The bundle is validated on its own, so locate its schema issues within the
+ * snapshot document, as entry issues are.
+ */
+const parseSnapshotBundle = <Bundle>(
+  value: unknown,
+  parse: (value: unknown) => Bundle,
+): Bundle => {
+  try {
+    return parse(value);
+  } catch (cause: unknown) {
+    if (!(cause instanceof z.ZodError)) throw cause;
+    throw new z.ZodError(
+      cause.issues.map((issue) => ({
+        ...issue,
+        path: ["evidence_bundle", ...issue.path],
+      })),
+    );
+  }
+};
+
 /** Reconstruct file entries only from fully authenticated matching Evidence. */
 export const parsePreparedAnalysisSnapshot = (
   input: unknown,
@@ -284,7 +305,10 @@ export const parsePreparedAnalysisSnapshot = (
   workflowEntries: readonly PreparedSnapshotEntry[],
 ): AnalysisSnapshot => {
   const header = snapshotFileHeaderSchema.parse(input);
-  const bundle = parseImmutableEvidenceBundle(header.evidence_bundle);
+  const bundle = parseSnapshotBundle(
+    header.evidence_bundle,
+    parseImmutableEvidenceBundle,
+  );
   const providerRows = entries.map((handle) => {
     const row = preparedEntries.get(handle);
     if (row?.kind !== "provider")
@@ -712,7 +736,7 @@ const authenticateSnapshot = (
   const parsed = analysisSnapshotSchema.parse(input);
   const restored = restoreSnapshot(
     parsed,
-    parseEvidenceBundle(parsed.evidence_bundle),
+    parseSnapshotBundle(parsed.evidence_bundle, parseEvidenceBundle),
     parsed.entries.map((entry) => ({
       kind: "provider",
       entry,
diff --git a/src/domain/evidenceErrors.ts b/src/domain/evidenceErrors.ts
index 2949c7dbf4..97afe2c867 100644
--- a/src/domain/evidenceErrors.ts
+++ b/src/domain/evidenceErrors.ts
@@ -24,6 +24,10 @@ export class EvidenceIntegrityError extends AnalysisError {
   readonly side: "left" | "right" | undefined;
   /** The first failing location inside that Evidence or its result, when schema-located. */
   readonly issuePath: readonly (string | number)[] | undefined;
+  /** The constraint a schema refinement named on that first issue. */
+  readonly constraint: string | undefined;
+  /** Schema issues after the first, which the message only summarizes. */
+  readonly remainingIssueCount: number | undefined;
 
   constructor(
     message: string,
@@ -31,12 +35,16 @@ export class EvidenceIntegrityError extends AnalysisError {
       readonly userMessage?: string;
       readonly side?: "left" | "right";
       readonly issuePath?: readonly (string | number)[];
+      readonly constraint?: string;
+      readonly remainingIssueCount?: number;
     },
   ) {
     super(message, options);
     this.userMessage = options?.userMessage;
     this.side = options?.side;
     this.issuePath = options?.issuePath;
+    this.constraint = options?.constraint;
+    this.remainingIssueCount = options?.remainingIssueCount;
   }
 }
 
diff --git a/src/domain/evidenceValidation.ts b/src/domain/evidenceValidation.ts
index d03a4c9309..ea38e41bb5 100644
--- a/src/domain/evidenceValidation.ts
+++ b/src/domain/evidenceValidation.ts
@@ -4,7 +4,7 @@ import { parseEvidence, immutableEvidence, type Evidence } from "./evidence.js";
 import { EvidenceIntegrityError } from "./evidenceErrors.js";
 import {
   describeValidationFailure,
-  firstValidationIssuePath,
+  firstValidationIssue,
 } from "./validationFailure.js";
 import { err, ok, type Result } from "./result.js";
 
@@ -74,19 +74,36 @@ export const readEvidencePayload = <Output>(
     : err(integrityFailure(parsed.error, location));
 };
 
-/** The issue path is reported only when its position in the record is known. */
+/**
+ * Schema issue facts for an integrity failure. The issue path is reported
+ * only when its position in the record (`within`) is known.
+ */
+export const validationIssueOptions = (
+  cause: unknown,
+  within?: readonly (string | number)[],
+): {
+  readonly issuePath?: readonly (string | number)[];
+  readonly constraint?: string;
+  readonly remainingIssueCount?: number;
+} => {
+  const issue = firstValidationIssue(cause);
+  if (issue === undefined) return {};
+  return {
+    ...(within === undefined ? {} : { issuePath: [...within, ...issue.path] }),
+    ...(issue.constraint === undefined ? {} : { constraint: issue.constraint }),
+    remainingIssueCount: issue.remainingIssueCount,
+  };
+};
+
 const integrityFailure = (
   cause: z.ZodError,
   location: EvidenceSourceLocation | undefined,
 ): EvidenceIntegrityError => {
   const message = `Evidence validation failed ${describeValidationFailure(cause)}`;
-  const issuePath = firstValidationIssuePath(cause);
   return new EvidenceIntegrityError(message, {
     cause,
     userMessage: message,
     ...(location?.side === undefined ? {} : { side: location.side }),
-    ...(location?.within === undefined || issuePath === undefined
-      ? {}
-      : { issuePath: [...location.within, ...issuePath] }),
+    ...validationIssueOptions(cause, location?.within),
   });
 };
diff --git a/src/domain/functionComparisonSchemas.ts b/src/domain/functionComparisonSchemas.ts
index 4a38ac365e..cdffb88a69 100644
--- a/src/domain/functionComparisonSchemas.ts
+++ b/src/domain/functionComparisonSchemas.ts
@@ -174,6 +174,7 @@ export const functionComparisonResultSchema = z
         path: ["status"],
         message:
           "Function comparison status contradicts its dimensions or function match.",
+        params: { constraint: "status-matches-dimensions" },
       });
   });
 
diff --git a/src/domain/functionDossierEvidence.ts b/src/domain/functionDossierEvidence.ts
index 2aa61383af..51d19a9ee6 100644
--- a/src/domain/functionDossierEvidence.ts
+++ b/src/domain/functionDossierEvidence.ts
@@ -68,14 +68,17 @@ export const parseFunctionEvidence = (
   const parsed = readEvidence(input, side);
   if (!parsed.ok) return parsed;
   const evidence = parsed.value;
-  const invalidSelection = (message: string, expected?: JsonValue) =>
+  const invalidSelection = (
+    message: string,
+    facts?: { readonly expected: JsonValue; readonly observed: JsonValue },
+  ) =>
     err(
       new AnalysisInputError(selection.operation, { userMessage: message }, [
         {
           path: selection.path,
           reason: "invalid_value",
           message,
-          ...(expected === undefined ? {} : { expected }),
+          ...facts,
         },
       ]),
     );
@@ -93,8 +96,14 @@ export const parseFunctionEvidence = (
     return invalidSelection(
       `Function analysis requires analyze_function Evidence with the rea.analysis predicate; the ${subject} has operation ${evidence.operation} and predicate ${evidence.predicate_type}.`,
       {
-        operation: "analyze_function",
-        predicate_type: ANALYSIS_EVIDENCE_PREDICATE,
+        expected: {
+          operation: "analyze_function",
+          predicate_type: ANALYSIS_EVIDENCE_PREDICATE,
+        },
+        observed: {
+          operation: evidence.operation,
+          predicate_type: evidence.predicate_type,
+        },
       },
     );
   }
diff --git a/src/domain/process/processComparison.ts b/src/domain/process/processComparison.ts
index 3a4cf8295c..6b72113798 100644
--- a/src/domain/process/processComparison.ts
+++ b/src/domain/process/processComparison.ts
@@ -101,6 +101,7 @@ export const processCaptureComparisonSchema = z
         code: "custom",
         message: "Process comparison status contradicts its dimensions",
         path: ["status"],
+        params: { constraint: "status-matches-dimensions" },
       });
   });
 export type ProcessCaptureComparison = z.infer<
diff --git a/src/domain/validationFailure.ts b/src/domain/validationFailure.ts
index 1beb743682..74eff909b5 100644
--- a/src/domain/validationFailure.ts
+++ b/src/domain/validationFailure.ts
@@ -1,14 +1,34 @@
 import { z } from "zod";
 
-/** The location `describeValidationFailure` names, when the cause is schema-located. */
-export const firstValidationIssuePath = (
+/**
+ * What `describeValidationFailure` states in prose, as facts a caller can act
+ * on without reading the description.
+ */
+export interface ValidationIssueFacts {
+  /** The first issue's location. */
+  readonly path: readonly (string | number)[];
+  /** The constraint a custom refinement named on the first issue. */
+  readonly constraint: string | undefined;
+  /** Further issues the description summarizes as "(N more issues)". */
+  readonly remainingIssueCount: number;
+}
+
+/** The first schema issue's facts, when the cause is a schema failure. */
+export const firstValidationIssue = (
   cause: unknown,
-): readonly (string | number)[] | undefined => {
+): ValidationIssueFacts | undefined => {
   if (!(cause instanceof z.ZodError)) return undefined;
-  const first = cause.issues[0];
-  return first?.path.map((key) =>
-    typeof key === "number" ? key : String(key),
-  );
+  const [first, ...rest] = cause.issues;
+  if (first === undefined) return undefined;
+  const constraint: unknown =
+    first.code === "custom" ? first.params?.["constraint"] : undefined;
+  return {
+    path: first.path.map((key) =>
+      typeof key === "number" ? key : String(key),
+    ),
+    constraint: typeof constraint === "string" ? constraint : undefined,
+    remainingIssueCount: rest.length,
+  };
 };
 
 /** Locate the first schema issue, or keep a thrown constraint message. */
diff --git a/tests/acceptance/analysisSnapshotDiagnostics.test.ts b/tests/acceptance/analysisSnapshotDiagnostics.test.ts
index 3b993bbb2e..dfec193d14 100644
--- a/tests/acceptance/analysisSnapshotDiagnostics.test.ts
+++ b/tests/acceptance/analysisSnapshotDiagnostics.test.ts
@@ -55,14 +55,17 @@ cliTest(
           code: "evidence_integrity_mismatch",
           category: "integrity_mismatch",
           retryable: false,
-          details: { reason: expect.stringContaining(`at ${field}:`) },
+          details: {
+            reason: expect.stringContaining(`at ${field}:`),
+            issue_path: field
+              .split(".")
+              .map((key) => (/^\d+$/u.test(key) ? Number(key) : key)),
+          },
         });
         expect(error).not.toHaveProperty("cause");
         expect(error).not.toHaveProperty("stack");
         if (field === "target")
-          expect(error.details?.reason).toMatch(
-            / at target: .+ \(2 more issues\)$/,
-          );
+          expect(error.details?.remaining_issue_count).toBe(2);
       }
       // MCP adds open-session facts; the snapshot reason must match exactly.
       expect(mcpError.details).toMatchObject(cliError.details ?? {});
diff --git a/tests/boundary/filesystem/analysisSnapshotInput.test.ts b/tests/boundary/filesystem/analysisSnapshotInput.test.ts
index 29af35ae05..2e856df4c4 100644
--- a/tests/boundary/filesystem/analysisSnapshotInput.test.ts
+++ b/tests/boundary/filesystem/analysisSnapshotInput.test.ts
@@ -58,12 +58,15 @@ describe.each([
         code: "evidence_integrity_mismatch",
         category: "integrity_mismatch",
         retryable: false,
-        details: { reason: expect.stringContaining(`at ${field}:`) },
+        details: {
+          reason: expect.stringContaining(`at ${field}:`),
+          issue_path: field
+            .split(".")
+            .map((key) => (/^\d+$/u.test(key) ? Number(key) : key)),
+        },
       });
       if (field === "target")
-        expect(projected.details?.reason).toMatch(
-          / at target: .+ \(2 more issues\)$/,
-        );
+        expect(projected.details?.remaining_issue_count).toBe(2);
       expect(projected).not.toHaveProperty("cause");
       expect(projected).not.toHaveProperty("stack");
       expect(await readFile(path, "utf8")).toBe(encoded);
@@ -144,6 +147,39 @@ it("refuses a snapshot holding an earlier-format bundle with the recreate guidan
   });
 });
 
+it("locates a bundle schema issue within the snapshot when reading and writing", async () => {
+  const root = await createTestTempDirectory("rea-snapshot-bundle-issue-");
+  const { providers: _providers, ...bundle } = createEvidenceBundle([]);
+  const snapshot = {
+    target: snapshotTarget(ANALYSIS_SNAPSHOT_TARGET),
+    binding: snapshotBinding(ANALYSIS_SNAPSHOT_PROFILE),
+    entries: [],
+    workflow_entries: [],
+    evidence_bundle: bundle,
+  };
+  const path = join(root, "snapshot.json");
+  await writeFile(path, JSON.stringify(snapshot));
+  const read = await readAnalysisSnapshot(path);
+  const written = await withArtifactResourceScope((resources) =>
+    writeAnalysisSnapshot(
+      snapshot as never,
+      join(root, "written.json"),
+      false,
+      resources,
+    ),
+  );
+  for (const result of [read, written]) {
+    if (result.ok) throw new Error("Expected invalid bundle refusal");
+    expect(projectAnalysisError(result.error)).toMatchObject({
+      code: "evidence_integrity_mismatch",
+      details: {
+        reason: expect.stringContaining("at evidence_bundle.providers:"),
+        issue_path: ["evidence_bundle", "providers"],
+      },
+    });
+  }
+});
+
 it("retains serialization schema diagnostics without creating a snapshot file", async () => {
   const root = await createTestTempDirectory("rea-snapshot-write-diagnostic-");
   const path = join(root, "snapshot.json");
diff --git a/tests/boundary/mcp/functionComparisonMcp.test.ts b/tests/boundary/mcp/functionComparisonMcp.test.ts
index 4bfed49443..7220b86e9c 100644
--- a/tests/boundary/mcp/functionComparisonMcp.test.ts
+++ b/tests/boundary/mcp/functionComparisonMcp.test.ts
@@ -314,10 +314,9 @@ describe("function comparison MCP integration", () => {
 });
 
 describe("function comparison input-kind diagnostics", () => {
+  // Each mismatch is checked once; alternating sides covers both labels.
   it.each([
     { side: "left", mismatch: "operation" },
-    { side: "right", mismatch: "operation" },
-    { side: "left", mismatch: "predicate" },
     { side: "right", mismatch: "predicate" },
   ] as const)(
     "rejects inline $side Evidence with the wrong $mismatch as an input-selection error",
@@ -350,11 +349,14 @@ describe("function comparison input-kind diagnostics", () => {
             {
               path: [side],
               reason: "invalid_value",
-              message: `Function analysis requires analyze_function Evidence with the rea.analysis predicate; the ${side} Evidence has operation ${wrong.operation} and predicate ${wrong.predicate_type}.`,
               expected: {
                 operation: "analyze_function",
                 predicate_type: "rea.analysis",
               },
+              observed: {
+                operation: wrong.operation,
+                predicate_type: wrong.predicate_type,
+              },
             },
           ],
         },
@@ -390,9 +392,7 @@ describe("function comparison input-kind diagnostics", () => {
         issues: [
           {
             path: ["left"],
-            message: expect.stringContaining(
-              "the left Evidence has operation inventory_artifact",
-            ),
+            observed: { operation: "inventory_artifact" },
           },
         ],
       },
@@ -531,11 +531,7 @@ it.each([
       const rejected = await verification(inconsistent.evidence_id);
       expect(parseMcpToolError(rejected).error).toMatchObject({
         code: "evidence_integrity_mismatch",
-        details: {
-          reason: expect.stringContaining(
-            "Function comparison status contradicts its dimensions or function match",
-          ),
-        },
+        details: { constraint: "status-matches-dimensions" },
       });
       expect(harness.session.evidenceById(inconsistent.evidence_id)).toEqual(
         inconsistent,
diff --git a/tests/boundary/mcp/processComparisonDiagnosticsMcp.test.ts b/tests/boundary/mcp/processComparisonDiagnosticsMcp.test.ts
index cdd77e8407..6a47a7f5cb 100644
--- a/tests/boundary/mcp/processComparisonDiagnosticsMcp.test.ts
+++ b/tests/boundary/mcp/processComparisonDiagnosticsMcp.test.ts
@@ -110,14 +110,14 @@ const compareViaCli = async (
   );
 };
 
-it.each(
-  (["left", "right"] as const).flatMap((missingWorker) =>
-    (["left", "right", "both", "neither"] as const).map((omittedRendered) => ({
-      missingWorker,
-      omittedRendered,
-    })),
-  ),
-)(
+// Each omission is checked once, alternating which side lacks the worker: a
+// one-sided omission on either side, both sides, and neither.
+it.each([
+  { missingWorker: "left", omittedRendered: "left" },
+  { missingWorker: "right", omittedRendered: "right" },
+  { missingWorker: "right", omittedRendered: "both" },
+  { missingWorker: "left", omittedRendered: "neither" },
+] as const)(
   "preserves terminal coverage when $missingWorker lacks a worker and $omittedRendered omits rendered output",
   async ({ missingWorker, omittedRendered }) => {
     const observation = (side: "left" | "right") => {
@@ -468,9 +468,11 @@ it("names the side and constraint when Evidence is not a usable capture", async
           {
             path: ["left"],
             reason: "invalid_value",
-            message: expect.stringContaining(
-              "the left Evidence has operation other",
-            ),
+            expected: {
+              operation: "capture_process_scenario",
+              predicate_type: "rea.process-capture",
+            },
+            observed: { operation: "other" },
           },
         ],
       },
@@ -552,7 +554,7 @@ it("names the side and constraint when Evidence is not a usable capture", async
         issues: [
           expect.objectContaining({
             path: ["right"],
-            observed: { issue_path: issuePath },
+            observed: expect.objectContaining({ issue_path: issuePath }),
           }),
         ],
       },
@@ -586,9 +588,6 @@ it("keeps structural capture issues alongside semantic ones through MCP and the
       },
     },
   });
-  // The count of remaining issues is only in the description.
-  const remaining = "(1 more issues)";
-
   const response = await client.callTool({
     name: "compare_process_captures",
     arguments: { left: capture, right: mixed },
@@ -596,23 +595,23 @@ it("keeps structural capture issues alongside semantic ones through MCP and the
   expect(parseMcpToolError(response)).toMatchObject({
     error: {
       code: "evidence_integrity_mismatch",
-      message: expect.stringContaining(remaining),
       details: {
         side: "right",
         issue_path: ["normalized_result", "manifest", "completed_at"],
+        remaining_issue_count: 1,
       },
     },
   });
   expect(await compareViaCli(capture, mixed)).toMatchObject({
     code: "invalid_request",
     category: "invalid_input",
-    message: expect.stringContaining(remaining),
     details: {
       issues: [
         {
           path: ["right"],
           observed: {
             issue_path: ["normalized_result", "manifest", "completed_at"],
+            remaining_issue_count: 1,
           },
         },
       ],
diff --git a/tests/boundary/mcp/processComparisonVerificationMcp.test.ts b/tests/boundary/mcp/processComparisonVerificationMcp.test.ts
index 5b9fb8f1c7..5f23638e65 100644
--- a/tests/boundary/mcp/processComparisonVerificationMcp.test.ts
+++ b/tests/boundary/mcp/processComparisonVerificationMcp.test.ts
@@ -101,11 +101,7 @@ it("rejects an inconsistent imported process comparison while retaining its Evid
     const rejected = await verify(inconsistent.evidence_id, selected);
     expect(parseMcpToolError(rejected).error).toMatchObject({
       code: "evidence_integrity_mismatch",
-      details: {
-        reason: expect.stringContaining(
-          "Process comparison status contradicts its dimensions",
-        ),
-      },
+      details: { constraint: "status-matches-dimensions" },
     });
     const failed = await verify(consistent.evidence_id, selected);
     expect(failed.isError).not.toBe(true);