diff --git a/src/browser/CdpCaptureDocuments.test.ts b/src/browser/CdpCaptureDocuments.test.ts
index c07dfdbe59..3629516051 100644
--- a/src/browser/CdpCaptureDocuments.test.ts
+++ b/src/browser/CdpCaptureDocuments.test.ts
@@ -2,13 +2,258 @@ import { describe, expect, it } from "vitest";
 
 import {
   captureAccessibility,
+  captureDom,
   captureFrames,
   captureResources,
 } from "./CdpCaptureDocuments.js";
+import { CdpCaptureCompleteness } from "./CdpCaptureCompleteness.js";
+import { inspectWebPageInputSchema } from "../domain/browserObservation.js";
 
 const origin = "https://app.example.test";
 
-describe("CDP document capture", () => {
+describe("CDP DOM capture", () => {
+  it("preserves node names and parents when aligned arrays are valid", () => {
+    const generator = captureDom(
+      {
+        strings: [origin + "/app", "#document", "DIV", "SPAN", ""],
+        documents: [
+          {
+            documentURL: 0,
+            baseURL: 0,
+            nodes: {
+              nodeType: [9, 1, 1],
+              nodeName: [1, 2, 3],
+              nodeValue: [4, 4, 4],
+              parentIndex: [-1, 0, 1],
+              attributes: [[], [], []],
+            },
+          },
+        ],
+      },
+      new Set([origin]),
+      inspectWebPageInputSchema.parse({
+        cdp_endpoint: "http://127.0.0.1:9222",
+        allowed_origins: [origin],
+        target_id: "page-1",
+      }),
+    );
+    let captured = generator.next([]);
+    while (!captured.done) captured = generator.next([]);
+    expect(captured.value.nodes.map((node) => node.node_name)).toEqual([
+      "#document",
+      "DIV",
+      "SPAN",
+    ]);
+    expect(captured.value.nodes.map((node) => node.parent_index)).toEqual([
+      -1, 0, 1,
+    ]);
+    expect(captured.value.nodes.map((node) => node.node_value_length)).toEqual([
+      0, 0, 0,
+    ]);
+  });
+
+  it.each(["nodeName", "parentIndex", "nodeValue", "attributes"] as const)(
+    "preserves DOM fact positions and reports malformed %s entries",
+    (field) => {
+      const strings = [
+        origin + "/app",
+        "#document",
+        "DIV",
+        "SPAN",
+        "href",
+        "title",
+        "/page",
+      ];
+      const nodeArrays: Record<string, unknown> = {
+        nodeType: [9, 1, 1],
+        nodeName: [1, 2, 3],
+        nodeValue: [0, 0, 0],
+        parentIndex: [-1, 0, 1],
+        attributes: [[], [], []],
+      };
+      if (field === "nodeName") nodeArrays.nodeName = [1, "malformed", 3];
+      if (field === "parentIndex")
+        nodeArrays.parentIndex = [-1, "malformed", 1];
+      if (field === "nodeValue") nodeArrays.nodeValue = [0, 0, "malformed"];
+      if (field === "attributes")
+        nodeArrays.attributes = [[], [4, "malformed", 5, 6], []];
+      const completeness = new CdpCaptureCompleteness();
+      const generator = captureDom(
+        {
+          strings,
+          documents: [
+            {
+              documentURL: 0,
+              baseURL: 0,
+              nodes: nodeArrays,
+            },
+          ],
+        },
+        new Set([origin]),
+        inspectWebPageInputSchema.parse({
+          cdp_endpoint: "http://127.0.0.1:9222",
+          allowed_origins: [origin],
+          target_id: "page-1",
+        }),
+        completeness,
+      );
+      let captured = generator.next([]);
+      while (!captured.done) captured = generator.next([]);
+      expect(captured.value.total).toBe(3);
+      expect(captured.value.nodes.map((node) => node.node_name)).toEqual(
+        field === "nodeValue" ? ["#document", "DIV"] : ["#document", "SPAN"],
+      );
+      expect(captured.value.nodes.map((node) => node.index)).toEqual(
+        field === "nodeValue" ? [0, 1] : [0, 2],
+      );
+      expect(captured.value.nodes.map((node) => node.parent_index)).toEqual(
+        field === "nodeValue" ? [-1, 0] : [-1, 1],
+      );
+      if (field === "attributes") {
+        expect(
+          captured.value.nodes.map((node) => node.attribute_names),
+        ).toEqual([[], []]);
+        expect(captured.value.urls).toEqual([]);
+      }
+      expect(completeness.snapshot()).toMatchObject({
+        unavailable_sections: expect.arrayContaining(["dom"]),
+        excluded: expect.arrayContaining([
+          { section: "dom", reason: "invalid_protocol_value", count: 1 },
+        ]),
+      });
+    },
+  );
+});
+
+describe("CDP DOM string and namespace validity", () => {
+  it.each([
+    { field: "nodeName", index: -1 },
+    { field: "nodeName", index: 20 },
+    { field: "nodeName", index: 2, malformedString: true },
+    { field: "nodeValue", index: -1 },
+    { field: "nodeValue", index: 20 },
+    { field: "nodeValue", index: 5, malformedString: true },
+    { field: "attributeName", index: -1 },
+    { field: "attributeName", index: 20 },
+    { field: "attributeValue", index: -1 },
+    { field: "attributeValue", index: 20 },
+  ] as const)(
+    "omits a node when its $field string index is invalid ($index)",
+    ({ field, index, malformedString }) => {
+      const strings: unknown[] = [
+        origin + "/app",
+        "#document",
+        "DIV",
+        "SPAN",
+        "href",
+        "/good",
+      ];
+      const nodeArrays: Record<string, unknown> = {
+        nodeType: [9, 1, 1],
+        nodeName: [1, 2, 3],
+        nodeValue: [0, 0, 0],
+        parentIndex: [-1, 0, 0],
+        attributes: [[], [], []],
+      };
+      if (field === "nodeName") nodeArrays.nodeName = [1, index, 3];
+      if (field === "nodeValue") nodeArrays.nodeValue = [0, index, 0];
+      if (field === "attributeName")
+        nodeArrays.attributes = [[], [index, 5], []];
+      if (field === "attributeValue")
+        nodeArrays.attributes = [[], [4, index], []];
+      if (malformedString === true) strings[index === 2 ? 2 : 5] = 42;
+      const completeness = new CdpCaptureCompleteness();
+      const generator = captureDom(
+        {
+          strings,
+          documents: [
+            {
+              documentURL: 0,
+              baseURL: 0,
+              nodes: nodeArrays,
+            },
+          ],
+        },
+        new Set([origin]),
+        inspectWebPageInputSchema.parse({
+          cdp_endpoint: "http://127.0.0.1:9222",
+          allowed_origins: [origin],
+          target_id: "page-1",
+        }),
+        completeness,
+      );
+      let captured = generator.next([]);
+      while (!captured.done) captured = generator.next([]);
+
+      expect(captured.value.total).toBe(3);
+      expect(captured.value.nodes.map((node) => node.index)).toEqual([0, 2]);
+      expect(captured.value.nodes.map((node) => node.node_name)).toEqual([
+        "#document",
+        "SPAN",
+      ]);
+      expect(completeness.snapshot().excluded).toContainEqual({
+        section: "dom",
+        reason: "invalid_protocol_value",
+        count: 1,
+      });
+    },
+  );
+
+  it("does not infer SVG ancestry through an element with malformed namespace data", () => {
+    const strings: unknown[] = [
+      origin + "/app",
+      "#document",
+      "svg",
+      "a",
+      "xmlns:xlink",
+      "http://www.w3.org/1999/xlink",
+      "xlink:href",
+      "/svg-link",
+    ];
+    const completeness = new CdpCaptureCompleteness();
+    const generator = captureDom(
+      {
+        strings,
+        documents: [
+          {
+            documentURL: 0,
+            baseURL: 0,
+            nodes: {
+              nodeType: [9, 1, 1],
+              nodeName: [1, 2, 3],
+              nodeValue: [0, 0, 0],
+              parentIndex: [-1, 0, 1],
+              attributes: [[], [4, 99], [6, 7]],
+            },
+          },
+        ],
+      },
+      new Set([origin]),
+      inspectWebPageInputSchema.parse({
+        cdp_endpoint: "http://127.0.0.1:9222",
+        allowed_origins: [origin],
+        target_id: "page-1",
+      }),
+      completeness,
+    );
+    let captured = generator.next([]);
+    while (!captured.done) captured = generator.next([]);
+
+    expect(captured.value.nodes.map((node) => node.index)).toEqual([0, 2]);
+    expect(captured.value.nodes[1]?.attribute_names).toEqual(["xlink:href"]);
+    expect(captured.value.urls).toEqual([]);
+    expect(
+      completeness
+        .snapshot()
+        .excluded.some(
+          ({ section, reason }) =>
+            section === "metadata" && reason === "invalid_protocol_value",
+        ),
+    ).toBe(true);
+  });
+});
+
+describe("CDP frame capture", () => {
   it("walks deeply nested frame trees and returns every frame and resource", () => {
     let frameTree: Record<string, unknown> = {
       frame: { id: "frame-0", url: `${origin}/0` },
@@ -30,7 +275,9 @@ describe("CDP document capture", () => {
     expect(frames.items).toHaveLength(2_000);
     expect(resources.items).toHaveLength(2_000);
   });
+});
 
+describe("CDP accessibility capture", () => {
   it("retains full approved accessibility text", () => {
     const capture = captureAccessibility(
       [
diff --git a/src/browser/CdpCaptureDocuments.ts b/src/browser/CdpCaptureDocuments.ts
index f95904fc0e..da7eb80192 100644
--- a/src/browser/CdpCaptureDocuments.ts
+++ b/src/browser/CdpCaptureDocuments.ts
@@ -174,7 +174,7 @@ export function* captureDom(
 > {
   const root = requiredRecord(result);
   const strings = Array.isArray(root.strings)
-    ? root.strings.map((value) => cdpStringValue(value) ?? "")
+    ? root.strings.map(cdpStringValue)
     : [];
   const nodes: WebPageInspection["dom"]["nodes"] = [];
   const urls: WebPageInspection["metadata"]["dom_urls"] = [];
@@ -184,44 +184,100 @@ export function* captureDom(
   let unresolvedSvgNodes = 0;
   for (const document of recordsValue(root.documents)) {
     const documentUrl = indexedString(strings, document.documentURL);
+    if (documentUrl === undefined) {
+      completeness?.exclude("dom", "invalid_protocol_value");
+      continue;
+    }
     if (allowedSanitizedUrl(documentUrl, allowedOrigins) === undefined) {
       completeness?.exclude("dom", exclusionReasonForUrl(documentUrl));
       continue;
     }
-    const baseUrl = indexedString(strings, document.baseURL) || documentUrl;
+    const baseUrlValue =
+      document.baseURL === undefined
+        ? documentUrl
+        : indexedString(strings, document.baseURL);
+    if (baseUrlValue === undefined) {
+      completeness?.exclude("dom", "invalid_protocol_value");
+      continue;
+    }
+    const baseUrl = baseUrlValue || documentUrl;
     const documentNodes = recordValue(document.nodes);
     if (documentNodes === undefined) continue;
-    const nodeTypes = numberArray(documentNodes.nodeType);
-    const nodeNames = numberArray(documentNodes.nodeName);
-    const nodeValues = numberArray(documentNodes.nodeValue);
-    const parents = numberArray(documentNodes.parentIndex);
-    const attributes = Array.isArray(documentNodes.attributes)
+    const rawNodeTypes = numberArray(documentNodes.nodeType);
+    const rawNodeNames = numberArray(documentNodes.nodeName);
+    const rawNodeValues = numberArray(documentNodes.nodeValue);
+    const rawParents = numberArray(documentNodes.parentIndex);
+    const rawAttributes = Array.isArray(documentNodes.attributes)
       ? documentNodes.attributes
-      : [];
+      : undefined;
+    if (
+      rawNodeTypes === undefined ||
+      rawNodeNames === undefined ||
+      rawNodeValues === undefined ||
+      rawParents === undefined ||
+      rawAttributes === undefined ||
+      rawNodeNames.length !== rawNodeTypes.length ||
+      rawNodeValues.length !== rawNodeTypes.length ||
+      rawParents.length !== rawNodeTypes.length
+    ) {
+      completeness?.exclude("dom", "invalid_protocol_value");
+      continue;
+    }
+    if (rawAttributes.length > rawNodeTypes.length)
+      completeness?.exclude(
+        "dom",
+        "invalid_protocol_value",
+        rawAttributes.length - rawNodeTypes.length,
+      );
     const backendNodeIds = Array.isArray(documentNodes.backendNodeId)
       ? documentNodes.backendNodeId
       : [];
-    const baseIndex = nodes.length;
+    const baseIndex = total;
+    total += rawNodeTypes.length;
     const ancestry = createDocumentSvgAncestry({
-      nodeTypes,
-      nodeNames,
-      parents,
+      nodeTypes: rawNodeTypes,
+      nodeNames: rawNodeNames,
+      parents: rawParents,
       strings,
-      attributes,
+      attributes: rawAttributes,
     });
-    total += nodeTypes.length;
     const pendingMetadata: PendingDomMetadata[] = [];
-    for (let index = 0; index < nodeTypes.length; index += 1) {
-      const attributeIndexes = numberArray(attributes[index]);
-      const parent = Math.trunc(parents[index] ?? -1);
-      const nodeIndex = nodes.length;
-      const nodeName = indexedString(strings, nodeNames[index]);
-      const attributeNames = uniqueAttributeNames(attributeIndexes, strings);
+    for (let index = 0; index < rawNodeTypes.length; index += 1) {
+      const nodeType = rawNodeTypes[index];
+      const nodeNameIndex = rawNodeNames[index];
+      const nodeValueIndex = rawNodeValues[index];
+      const parent = rawParents[index];
+      const attributeIndexes = numberArray(rawAttributes[index]);
+      const nodeName = indexedString(strings, nodeNameIndex);
+      const nodeValue = indexedString(strings, nodeValueIndex);
+      if (
+        nodeType === undefined ||
+        nodeName === undefined ||
+        nodeValue === undefined ||
+        parent === undefined ||
+        parent < -1 ||
+        parent === index ||
+        parent >= rawNodeTypes.length ||
+        attributeIndexes === undefined ||
+        attributeIndexes.length % 2 !== 0 ||
+        attributeIndexes.some(
+          (value) =>
+            value === undefined || indexedString(strings, value) === undefined,
+        )
+      ) {
+        completeness?.exclude("dom", "invalid_protocol_value");
+        continue;
+      }
+      const attributes = attributeIndexes as readonly number[];
+      const nodeIndex = baseIndex + index;
+      const attributeNames = uniqueAttributeNames(attributes, strings);
       const svgLink = domSvgLink(ancestry, index);
+      if (svgLink.xmlDocument === undefined)
+        completeness?.exclude("metadata", "invalid_protocol_value");
       let svgQuery: DomSvgNodeQuery | null | undefined;
       if (
-        !svgLink.xmlDocument &&
-        nodeTypes[index] === 1 &&
+        svgLink.xmlDocument === false &&
+        nodeType === 1 &&
         attributeNames.includes("xlink:href") &&
         !attributeNames.includes("href")
       ) {
@@ -236,16 +292,16 @@ export function* captureDom(
       nodes.push({
         index: nodeIndex,
         parent_index: parent < 0 ? -1 : baseIndex + parent,
-        node_type: Math.max(0, Math.trunc(nodeTypes[index] ?? 0)),
+        node_type: nodeType,
         node_name: nodeName,
-        node_value_length: indexedString(strings, nodeValues[index]).length,
+        node_value_length: nodeValue.length,
         attribute_names: attributeNames,
       });
       pendingMetadata.push({
         svgQuery,
         options: {
           strings,
-          attributes: attributeIndexes,
+          attributes,
           // The BASE element itself resolves against the document fallback URL.
           baseUrl: nodeName.toLowerCase() === "base" ? documentUrl : baseUrl,
           documentUrl,
@@ -257,7 +313,7 @@ export function* captureDom(
       });
       if (
         pendingMetadata.length === DOM_METADATA_BATCH_SIZE ||
-        index === nodeTypes.length - 1
+        index === rawNodeTypes.length - 1
       ) {
         const metadata = yield* captureDomMetadata(
           pendingMetadata,
@@ -270,6 +326,14 @@ export function* captureDom(
         pendingMetadata.length = 0;
       }
     }
+    if (pendingMetadata.length > 0) {
+      const metadata = yield* captureDomMetadata(pendingMetadata, completeness);
+      urls.push(...metadata.urls);
+      agentHints.push(...metadata.agentHints);
+      excludedUrls += metadata.excludedUrls;
+      unresolvedSvgNodes += metadata.unresolvedSvgNodes;
+      pendingMetadata.length = 0;
+    }
   }
   return {
     total,
@@ -450,19 +514,25 @@ const accessibilityStates = (
 const axText = (value: unknown): string | null =>
   cdpStringValue(recordValue(value)?.value) ?? null;
 
-const indexedString = (strings: readonly string[], index: unknown): string => {
+const indexedString = (
+  strings: readonly (string | undefined)[],
+  index: unknown,
+): string | undefined => {
   const integer = numberValue(index);
-  return integer === undefined ? "" : (strings[Math.trunc(integer)] ?? "");
+  if (integer === undefined || !Number.isSafeInteger(integer) || integer < 0)
+    return undefined;
+  return strings[integer];
 };
 
 const uniqueAttributeNames = (
   attributeIndexes: readonly number[],
-  strings: readonly string[],
+  strings: readonly (string | undefined)[],
 ): string[] => {
   const names: string[] = [];
   const seen = new Set<string>();
   for (let index = 0; index < attributeIndexes.length; index += 2) {
     const name = indexedString(strings, attributeIndexes[index]);
+    if (name === undefined) continue;
     if (seen.has(name)) continue;
     seen.add(name);
     names.push(name);
@@ -470,16 +540,20 @@ const uniqueAttributeNames = (
   return names;
 };
 
-const numberArray = (value: unknown): readonly number[] =>
-  Array.isArray(value)
-    ? value.flatMap((item) => {
-        const number = numberValue(item);
-        return number === undefined ? [] : [number];
-      })
-    : [];
+const numberArray = (
+  value: unknown,
+): readonly (number | undefined)[] | undefined => {
+  if (!Array.isArray(value)) return undefined;
+  return value.map((item) => {
+    const number = numberValue(item);
+    return number !== undefined && Number.isSafeInteger(number)
+      ? number
+      : undefined;
+  });
+};
 
 interface DomMetadataOptions {
-  readonly strings: readonly string[];
+  readonly strings: readonly (string | undefined)[];
   readonly attributes: readonly number[];
   readonly baseUrl: string;
   readonly documentUrl: string;
@@ -525,6 +599,7 @@ const domMetadata = (
     // Chrome already folds HTML names; SVG/XML names remain case-sensitive.
     const name = indexedString(strings, attributes[index]);
     const value = indexedString(strings, attributes[index + 1]);
+    if (name === undefined || value === undefined) continue;
     // HTML keeps the first declaration. A later repeat must not move dom_urls.
     if (!pairs.has(name)) pairs.set(name, value);
   }
diff --git a/src/browser/CdpCaptureDomSvg.ts b/src/browser/CdpCaptureDomSvg.ts
index 4d021766c9..2ffd8e31fd 100644
--- a/src/browser/CdpCaptureDomSvg.ts
+++ b/src/browser/CdpCaptureDomSvg.ts
@@ -4,10 +4,10 @@ const SVG_NAMESPACE = "http://www.w3.org/2000/svg";
 const XLINK_NAMESPACE = "http://www.w3.org/1999/xlink";
 
 interface DomSnapshotNodes {
-  readonly nodeTypes: readonly number[];
-  readonly nodeNames: readonly number[];
-  readonly parents: readonly number[];
-  readonly strings: readonly string[];
+  readonly nodeTypes: readonly (number | undefined)[];
+  readonly nodeNames: readonly (number | undefined)[];
+  readonly parents: readonly (number | undefined)[];
+  readonly strings: readonly (string | undefined)[];
   readonly attributes: readonly unknown[];
 }
 
@@ -17,7 +17,7 @@ interface XmlSvgLink {
 }
 
 interface DocumentSvgAncestry {
-  readonly xml: boolean;
+  readonly xml: boolean | undefined;
   readonly xmlLinks: Map<number, XmlSvgLink>;
 }
 
@@ -48,50 +48,59 @@ export const capturedSvgNodeKind = (
 
 interface DomSvgLink {
   readonly svgElement: boolean;
-  readonly xmlDocument: boolean;
+  readonly xmlDocument: boolean | undefined;
   readonly xlinkHref: string | undefined;
 }
 
-const UNRESOLVED: XmlSvgLink = {
-  svgElement: false,
-  xlinkHref: undefined,
-};
-
-const stringAt = (strings: readonly string[], index: unknown): string => {
+const stringAt = (
+  strings: readonly (string | undefined)[],
+  index: unknown,
+): string | undefined => {
   const integer = numberValue(index);
-  return integer === undefined ? "" : (strings[Math.trunc(integer)] ?? "");
+  if (integer === undefined || !Number.isSafeInteger(integer) || integer < 0)
+    return undefined;
+  return strings[integer];
 };
 
-const numberArray = (value: unknown): readonly number[] =>
+const numberArray = (value: unknown): readonly (number | undefined)[] =>
   Array.isArray(value)
-    ? value.flatMap((item) => {
+    ? value.map((item) => {
         const number = numberValue(item);
-        return number === undefined ? [] : [number];
+        return number !== undefined && Number.isSafeInteger(number)
+          ? number
+          : undefined;
       })
     : [];
 
 // DOMSnapshot has no namespace URI. HTML documents use uppercase `HTML` and
 // the parser's local names. XML documents preserve prefixed names and xmlns
 // declarations, including those on standalone SVG roots.
-const xmlDocument = (nodes: DomSnapshotNodes): boolean => {
-  const documentIndex = nodes.nodeTypes.findIndex(
-    (nodeType) => Math.trunc(nodeType) === 9,
-  );
+const xmlDocument = (nodes: DomSnapshotNodes): boolean | undefined => {
+  const documentIndex = nodes.nodeTypes.findIndex((nodeType) => nodeType === 9);
   if (documentIndex < 0) return false;
+  if (
+    !validSvgSourceNode(nodes, documentIndex) ||
+    nodes.parents[documentIndex] !== -1
+  )
+    return undefined;
   for (let index = 0; index < nodes.nodeTypes.length; index += 1) {
-    if (Math.trunc(nodes.nodeTypes[index] ?? 0) !== 1) continue;
-    if (Math.trunc(nodes.parents[index] ?? -1) !== documentIndex) continue;
+    if (nodes.nodeTypes[index] !== 1) continue;
+    if (nodes.parents[index] !== documentIndex) continue;
     const name = stringAt(nodes.strings, nodes.nodeNames[index]);
+    if (name === undefined || !validSvgSourceNode(nodes, index))
+      return undefined;
     if (name === "HTML") return false;
     if (name === "html" || name.includes(":")) return true;
     // Explicit namespaces also identify standalone SVG and other XML roots.
     // Namespace-free synthetic snapshots retain the legacy HTML behavior.
     const attributes = numberArray(nodes.attributes[index]);
-    return attributes.some(
-      (value, offset) =>
-        offset % 2 === 0 &&
-        xmlnsPrefix(stringAt(nodes.strings, value)) !== undefined,
-    );
+    for (let offset = 0; offset + 1 < attributes.length; offset += 2) {
+      const value = attributes[offset];
+      const attributeName = stringAt(nodes.strings, value);
+      if (attributeName === undefined) return undefined;
+      if (xmlnsPrefix(attributeName) !== undefined) return true;
+    }
+    return false;
   }
   return false;
 };
@@ -102,7 +111,7 @@ export const createDocumentSvgAncestry = (
   const xml = xmlDocument(nodes);
   return {
     xml,
-    xmlLinks: xml ? resolveXmlElements(nodes) : new Map(),
+    xmlLinks: xml === true ? resolveXmlElements(nodes) : new Map(),
   };
 };
 
@@ -110,14 +119,28 @@ export const domSvgLink = (
   ancestry: DocumentSvgAncestry,
   index: number,
 ): DomSvgLink => {
-  if (!ancestry.xml) {
+  if (ancestry.xml === false) {
     return {
       svgElement: false,
       xmlDocument: false,
       xlinkHref: undefined,
     };
   }
-  const resolved = ancestry.xmlLinks.get(index) ?? UNRESOLVED;
+  if (ancestry.xml === undefined) {
+    return {
+      svgElement: false,
+      xmlDocument: undefined,
+      xlinkHref: undefined,
+    };
+  }
+  const resolved = ancestry.xmlLinks.get(index);
+  if (resolved === undefined) {
+    return {
+      svgElement: false,
+      xmlDocument: undefined,
+      xlinkHref: undefined,
+    };
+  }
   return {
     svgElement: resolved.svgElement,
     xmlDocument: true,
@@ -143,7 +166,9 @@ const resolveXmlElements = (
   const children = new Map<number, number[]>();
   const pending: XmlWalkStep[] = [];
   for (let node = 0; node < nodes.nodeNames.length; node += 1) {
-    const parent = Math.trunc(nodes.parents[node] ?? -1);
+    const parent = nodes.parents[node];
+    if (parent === undefined || parent < -1 || parent >= nodes.nodeNames.length)
+      continue;
     if (parent < 0) pending.push({ node });
     else if (parent < nodes.nodeNames.length && parent !== node) {
       const siblings = children.get(parent);
@@ -164,10 +189,11 @@ const resolveXmlElements = (
       continue;
     }
     const { node } = step;
+    if (!validSvgSourceNode(nodes, node)) continue;
     const attributes = numberArray(nodes.attributes[node]);
     const restore = applyDeclarations(bindings, attributes, nodes.strings);
     const svgElement =
-      Math.trunc(nodes.nodeTypes[node] ?? 0) === 1 &&
+      nodes.nodeTypes[node] === 1 &&
       elementNamespace(
         stringAt(nodes.strings, nodes.nodeNames[node]),
         bindings,
@@ -188,24 +214,30 @@ const resolveXmlElements = (
 
 const applyDeclarations = (
   bindings: Map<string, string>,
-  attributes: readonly number[],
-  strings: readonly string[],
+  attributes: readonly (number | undefined)[],
+  strings: readonly (string | undefined)[],
 ): readonly NamespaceRestore[] => {
   const restore: NamespaceRestore[] = [];
   const seen = new Set<string>();
   for (let index = 0; index + 1 < attributes.length; index += 2) {
-    const prefix = xmlnsPrefix(stringAt(strings, attributes[index]));
+    const nameIndex = attributes[index];
+    const valueIndex = attributes[index + 1];
+    if (nameIndex === undefined || valueIndex === undefined) continue;
+    const name = stringAt(strings, nameIndex);
+    const value = stringAt(strings, valueIndex);
+    if (name === undefined || value === undefined) continue;
+    const prefix = xmlnsPrefix(name);
     if (prefix === undefined || seen.has(prefix)) continue;
     seen.add(prefix);
     restore.push({ prefix, previous: bindings.get(prefix) });
-    const value = stringAt(strings, attributes[index + 1]);
     if (value.length === 0) bindings.delete(prefix);
     else bindings.set(prefix, value);
   }
   return restore;
 };
 
-const xmlnsPrefix = (name: string): string | undefined => {
+const xmlnsPrefix = (name: string | undefined): string | undefined => {
+  if (name === undefined) return undefined;
   if (name === "xmlns") return "";
   if (!name.startsWith("xmlns:")) return undefined;
   const prefix = name.slice("xmlns:".length);
@@ -215,9 +247,10 @@ const xmlnsPrefix = (name: string): string | undefined => {
 };
 
 const elementNamespace = (
-  nodeName: string,
+  nodeName: string | undefined,
   bindings: ReadonlyMap<string, string>,
 ): string => {
+  if (nodeName === undefined) return "";
   const colon = nodeName.indexOf(":");
   if (colon < 0) return bindings.get("") ?? "";
   const prefix = nodeName.slice(0, colon);
@@ -235,13 +268,17 @@ const elementNamespace = (
 // First prefixed href bound to the XLink namespace. Duplicate names keep the
 // earlier value. Plain href is applied by the caller and wins even when empty.
 const xlinkHrefValue = (
-  attributes: readonly number[],
-  strings: readonly string[],
+  attributes: readonly (number | undefined)[],
+  strings: readonly (string | undefined)[],
   bindings: ReadonlyMap<string, string>,
 ): string | undefined => {
   const seen = new Set<string>();
   for (let index = 0; index + 1 < attributes.length; index += 2) {
-    const name = stringAt(strings, attributes[index]);
+    const nameIndex = attributes[index];
+    const valueIndex = attributes[index + 1];
+    if (nameIndex === undefined || valueIndex === undefined) continue;
+    const name = stringAt(strings, nameIndex);
+    if (name === undefined) continue;
     if (seen.has(name)) continue;
     seen.add(name);
     const colon = name.indexOf(":");
@@ -249,7 +286,30 @@ const xlinkHrefValue = (
     const prefix = name.slice(0, colon);
     const local = name.slice(colon + 1);
     if (local !== "href" || bindings.get(prefix) !== XLINK_NAMESPACE) continue;
-    return stringAt(strings, attributes[index + 1]);
+    return stringAt(strings, valueIndex);
   }
   return undefined;
 };
+
+const validSvgSourceNode = (
+  nodes: DomSnapshotNodes,
+  index: number,
+): boolean => {
+  if (
+    nodes.nodeTypes[index] === undefined ||
+    stringAt(nodes.strings, nodes.nodeNames[index]) === undefined
+  )
+    return false;
+  const rawAttributes = nodes.attributes[index];
+  if (!Array.isArray(rawAttributes) || rawAttributes.length % 2 !== 0)
+    return false;
+  const attributes = numberArray(rawAttributes);
+  return (
+    attributes.length === rawAttributes.length &&
+    attributes.every(
+      (attribute) =>
+        attribute !== undefined &&
+        stringAt(nodes.strings, attribute) !== undefined,
+    )
+  );
+};
diff --git a/src/browser/CdpCaptureStorage.test.ts b/src/browser/CdpCaptureStorage.test.ts
index 51bb49a08d..72665f1b43 100644
--- a/src/browser/CdpCaptureStorage.test.ts
+++ b/src/browser/CdpCaptureStorage.test.ts
@@ -82,3 +82,61 @@ it.each([false, true])(
     expect(value.fingerprints_complete).toBe(!mixed);
   },
 );
+
+it("keeps an omitted IndexedDB remote value unknown", async () => {
+  const replies: Record<string, unknown> = {
+    "Storage.getUsageAndQuota": { usage: 0, quota: 1000 },
+    "DOMStorage.getDOMStorageItems": { entries: [] },
+    "IndexedDB.requestDatabaseNames": { databaseNames: ["db"] },
+    "CacheStorage.requestCacheNames": { caches: [] },
+    "Network.getCookies": { cookies: [] },
+    "IndexedDB.requestDatabase": {
+      databaseWithObjectStores: {
+        name: "db",
+        objectStores: [
+          {
+            name: "records",
+            keyPath: { type: "string", string: "id" },
+            autoIncrement: false,
+            indexes: [],
+          },
+        ],
+      },
+    },
+    "IndexedDB.requestData": {
+      objectStoreDataEntries: [
+        {
+          key: { type: "number", value: 1 },
+          primaryKey: { type: "number", value: 1 },
+        },
+      ],
+      hasMore: false,
+    },
+  };
+  const connection = {
+    async send(method: string): Promise<unknown> {
+      if (!(method in replies)) throw new Error(method);
+      return replies[method];
+    },
+  } as unknown as CdpConnection;
+  const { value } = await captureStorage(
+    {
+      connection,
+      sessionId: undefined,
+      input: inspectWebPageInputSchema.parse({
+        cdp_endpoint: "http://127.0.0.1:9222",
+        allowed_origins: ["https://example.test"],
+        target_id: "page-1",
+        include_storage_keys: true,
+        include_storage_fingerprints: true,
+      }),
+    },
+    "https://example.test/app",
+    [],
+  );
+  const record = value.content_fingerprints.find(
+    (item) => item.scope === "indexed_db_record",
+  );
+  expect(record).toMatchObject({ value_sha256: null, complete: false });
+  expect(value.fingerprints_complete).toBe(false);
+});
diff --git a/src/browser/CdpCaptureStorageFingerprints.ts b/src/browser/CdpCaptureStorageFingerprints.ts
index ec7a068500..9f8f80c525 100644
--- a/src/browser/CdpCaptureStorageFingerprints.ts
+++ b/src/browser/CdpCaptureStorageFingerprints.ts
@@ -301,7 +301,10 @@ const addIndexedDbRecords = async (
     for (const entry of entries) {
       const key = stableValue(entry.key);
       const primaryKey = stableValue(entry.primaryKey);
-      const value = stableValue(entry.value);
+      // A missing remote object is an omission, not the JavaScript value
+      // "undefined". Keep the unavailable digest null and coverage partial.
+      const value =
+        entry.value === undefined ? undefined : stableValue(entry.value);
       addFingerprint(run.state, {
         scope: "indexed_db_record",
         identity: {
diff --git a/src/browser/CdpConnection.ts b/src/browser/CdpConnection.ts
index 3c7e5e86a9..e970056686 100644
--- a/src/browser/CdpConnection.ts
+++ b/src/browser/CdpConnection.ts
@@ -243,9 +243,9 @@ export class CdpConnection {
     const hasResult = "result" in message;
     const hasError = "error" in message;
     if (
-      ("sessionId" in message &&
-        (typeof message.sessionId !== "string" ||
-          message.sessionId !== pending.sessionId)) ||
+      (pending.sessionId === undefined
+        ? "sessionId" in message
+        : message.sessionId !== pending.sessionId) ||
       hasResult === hasError
     ) {
       this.#failPending("protocol_error");
diff --git a/src/browser/CdpElectronInspection.test.ts b/src/browser/CdpElectronInspection.test.ts
new file mode 100644
index 0000000000..925b10e9f1
--- /dev/null
+++ b/src/browser/CdpElectronInspection.test.ts
@@ -0,0 +1,64 @@
+import { mkdtemp, rm, writeFile } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { pathToFileURL } from "node:url";
+
+import { afterEach, describe, expect, it } from "vitest";
+
+import { CdpCaptureCompleteness } from "./CdpCaptureCompleteness.js";
+import { captureFrames } from "./CdpElectronInspection.js";
+
+const temporary: string[] = [];
+
+afterEach(async () => {
+  await Promise.all(
+    temporary
+      .splice(0)
+      .map((path) => rm(path, { recursive: true, force: true })),
+  );
+});
+
+describe("Electron frame capture", () => {
+  it.each([7, undefined])(
+    "classifies a malformed child frame ID as unavailable: %s",
+    async (childId) => {
+      const root = await mkdtemp(join(tmpdir(), "rea-electron-frame-"));
+      temporary.push(root);
+      const main = join(root, "index.html");
+      const child = join(root, "child.html");
+      await Promise.all([writeFile(main, "main"), writeFile(child, "child")]);
+      const mainUrl = pathToFileURL(main).href;
+      const childUrl = pathToFileURL(child).href;
+      const completeness = new CdpCaptureCompleteness();
+
+      const frames = await captureFrames(
+        {
+          frameTree: {
+            frame: { id: "frame-main", url: mainUrl },
+            childFrames: [
+              {
+                frame: {
+                  ...(childId === undefined ? {} : { id: childId }),
+                  url: childUrl,
+                },
+              },
+            ],
+          },
+        },
+        completeness,
+      );
+
+      expect(frames.map((frame) => frame.frame_id)).toEqual(["frame-main"]);
+      expect(completeness.snapshot()).toMatchObject({
+        unavailable_sections: ["frames"],
+        excluded: [
+          { section: "frames", reason: "invalid_protocol_value", count: 1 },
+        ],
+      });
+      expect(completeness.snapshot().policy_filtered_sections).not.toContain(
+        "frames",
+      );
+      expect(completeness.snapshot().conditions).toContain("attach_limited");
+    },
+  );
+});
diff --git a/src/browser/CdpElectronInspection.ts b/src/browser/CdpElectronInspection.ts
index e1eb616f97..cf6613f774 100644
--- a/src/browser/CdpElectronInspection.ts
+++ b/src/browser/CdpElectronInspection.ts
@@ -232,7 +232,7 @@ const navigatedFrameId = (event: CdpEvent): string | undefined => {
   return undefined;
 };
 
-const captureFrames = async (
+export const captureFrames = async (
   result: unknown,
   completeness: CdpCaptureCompleteness,
 ): Promise<ElectronPageInspection["frames"]> => {
@@ -245,8 +245,12 @@ const captureFrames = async (
   )) {
     const frame = recordValue(tree.frame);
     const frameId = cdpStringValue(frame?.id);
-    const path = await authorizedElectronFile(cdpStringValue(frame?.url) ?? "");
-    if (frameId === undefined || path === undefined) {
+    if (frame === undefined || frameId === undefined) {
+      completeness.exclude("frames", "invalid_protocol_value");
+      continue;
+    }
+    const path = await authorizedElectronFile(cdpStringValue(frame.url) ?? "");
+    if (path === undefined) {
       completeness.exclude("frames", "out_of_target_scope");
       continue;
     }
diff --git a/src/browser/CdpScreenshot.ts b/src/browser/CdpScreenshot.ts
index b29ab121db..e4093479b1 100644
--- a/src/browser/CdpScreenshot.ts
+++ b/src/browser/CdpScreenshot.ts
@@ -94,7 +94,7 @@ export const captureCdpScreenshot = async (
   const bytes =
     encoded === undefined ? undefined : decodeCanonicalBase64(encoded);
   if (bytes === undefined)
-    throw new BrowserObservationError("inspect_web_page", "payload_limit");
+    throw new BrowserObservationError("inspect_web_page", "protocol_error");
   const dimensions = readPngHeaderDimensions(bytes);
   if (dimensions === undefined)
     throw new BrowserObservationError("inspect_web_page", "protocol_error");
diff --git a/src/browser/PlaywrightElectronActiveProjection.test.ts b/src/browser/PlaywrightElectronActiveProjection.test.ts
index baec9b2194..09a5b6910e 100644
--- a/src/browser/PlaywrightElectronActiveProjection.test.ts
+++ b/src/browser/PlaywrightElectronActiveProjection.test.ts
@@ -40,12 +40,15 @@ it("projects hook retention and dropped event families through the result schema
         estimated_retained_bytes: 1_024,
         event_serialized_byte_upper_bound: 512,
         retained: 1,
-        dropped: 1,
+        dropped: 2,
         dropped_ipc: 0,
-        dropped_runtime: 1,
-        dropped_event_families: [{ family: "renderer-ipc", count: 1 }],
+        dropped_runtime: 2,
+        dropped_event_families: [
+          { family: "renderer-ipc", count: 1 },
+          { family: "preload-configuration", count: 1 },
+        ],
         dropped_event_roles: [{ role: "renderer", count: 1 }],
-        observed: 2,
+        observed: 3,
         observed_ipc: 1,
         observed_runtime: 1,
         hook_error: false,
@@ -58,18 +61,29 @@ it("projects hook retention and dropped event families through the result schema
     estimated_retained_bytes: 1_024,
     event_serialized_byte_upper_bound: 512,
     retained: 1,
-    dropped: 1,
-    dropped_event_families: [{ family: "renderer-ipc", count: 1 }],
+    dropped: 2,
+    dropped_event_families: [
+      { family: "renderer-ipc", count: 1 },
+      { family: "preload-configuration", count: 1 },
+    ],
     dropped_event_roles: [{ role: "renderer", count: 1 }],
   });
   expect(result.ipc).toMatchObject({ observed: 1, dropped: 0 });
-  expect(result.timeline).toMatchObject({ observed: 2, dropped: 1 });
+  expect(result.timeline).toMatchObject({ observed: 3, dropped: 2 });
   expect(result.coverage.observed_event_families).toContain("renderer-ipc");
   expect(result.coverage.unavailable_event_families).not.toContain(
     "renderer-ipc",
   );
   expect(result.coverage.observed_roles).toContain("renderer");
-  expect(result.coverage.unavailable_event_families).toContain("preload");
+  expect(result.coverage.observed_event_families).toContain(
+    "preload-configuration",
+  );
+  expect(result.coverage.unavailable_event_families).not.toContain(
+    "preload-configuration",
+  );
+  expect(result.limitations).not.toContain(
+    "Preload configuration was not exposed by the observed Electron window metadata. Preload paths and execution remain unavailable.",
+  );
 });
 
 it("keeps renderer coverage unavailable when only the main process was observed", () => {
diff --git a/src/browser/PlaywrightElectronActiveProjection.ts b/src/browser/PlaywrightElectronActiveProjection.ts
index e7b79d633f..71f5581b28 100644
--- a/src/browser/PlaywrightElectronActiveProjection.ts
+++ b/src/browser/PlaywrightElectronActiveProjection.ts
@@ -113,6 +113,18 @@ const createCoverage = (hookSnapshot: ElectronHookSnapshot) => {
   } as const;
 };
 
+const hasObservedPreloadConfiguration = (
+  hookSnapshot: ElectronHookSnapshot,
+): boolean =>
+  hookSnapshot.events.some(
+    ({ kind, process_type }) =>
+      kind === "preload" &&
+      (process_type === "main" || process_type === "browser"),
+  ) ||
+  hookSnapshot.dropped_event_families.some(
+    ({ family, count }) => family === "preload-configuration" && count > 0,
+  );
+
 /** Project one provider hook snapshot into the canonical public result. */
 export const projectElectronActiveCapture = (
   paths: ElectronCapturePaths,
@@ -166,7 +178,7 @@ export const projectElectronActiveCapture = (
       "IPC direction and sender/receiver identifiers are observed only where Electron exposes them at the hooked boundary.",
       "The runtime timeline records lifecycle, navigation, shell, permission, popup, download, protocol, preload, native-addon, process, and IPC events; activity before hook installation is unavailable.",
       "The preload and renderer process contexts are not instrumented by the main-process -r hook; preload configuration and contextBridge API-shape events are main-boundary observations, not proof of renderer-side execution.",
-      ...(!hookSnapshot.events.some(({ kind }) => kind === "preload")
+      ...(!hasObservedPreloadConfiguration(hookSnapshot)
         ? [
             "Preload configuration was not exposed by the observed Electron window metadata. Preload paths and execution remain unavailable.",
           ]
diff --git a/src/browser/PlaywrightElectronActiveProvider.test.ts b/src/browser/PlaywrightElectronActiveProvider.test.ts
index 50f9905d51..9bdaaf3cdf 100644
--- a/src/browser/PlaywrightElectronActiveProvider.test.ts
+++ b/src/browser/PlaywrightElectronActiveProvider.test.ts
@@ -73,6 +73,23 @@ const ownership = {
   expectedParentPid: 1,
 } satisfies OwnedProcessGroup;
 
+const emptyHookSnapshot = () => ({
+  events: [],
+  retention_budget_bytes: 0,
+  estimated_retained_bytes: 0,
+  event_serialized_byte_upper_bound: 0,
+  retained: 0,
+  dropped: 0,
+  dropped_ipc: 0,
+  dropped_runtime: 0,
+  dropped_event_families: [],
+  dropped_event_roles: [],
+  observed: 0,
+  observed_ipc: 0,
+  observed_runtime: 0,
+  hook_error: false,
+});
+
 it("does not signal a Windows Electron PID when lineage is unavailable", async () => {
   const terminateTree = vi.fn(async () => ({
     cleaned: true as const,
@@ -138,27 +155,11 @@ it("retains the partial capture without taskkill when Windows lineage is unavail
   const terminateTree = vi
     .spyOn(processOwnership, "cleanupWindowsProcessTree")
     .mockResolvedValue({ cleaned: true, signaled: true });
-  const hookSnapshot = {
-    events: [],
-    retention_budget_bytes: 0,
-    estimated_retained_bytes: 0,
-    event_serialized_byte_upper_bound: 0,
-    retained: 0,
-    dropped: 0,
-    dropped_ipc: 0,
-    dropped_runtime: 0,
-    dropped_event_families: [],
-    dropped_event_roles: [],
-    observed: 0,
-    observed_ipc: 0,
-    observed_runtime: 0,
-    hook_error: false,
-  };
   vi.spyOn(electronActions, "readApplicationState").mockResolvedValue({
     windows: [],
     metrics: [],
     electronVersion: "44.0.0",
-    hookSnapshot,
+    hookSnapshot: emptyHookSnapshot(),
   });
   const application = {
     process: () => ({ pid: 424242 }),
@@ -206,3 +207,49 @@ it("retains the partial capture without taskkill when Windows lineage is unavail
       Object.defineProperty(process, "platform", originalPlatform);
   }
 });
+
+it("retains the initial snapshot when the final state read fails", async () => {
+  const initialState = {
+    windows: [],
+    metrics: [],
+    electronVersion: "44.0.0",
+    hookSnapshot: emptyHookSnapshot(),
+  };
+  vi.spyOn(electronActions, "readApplicationState")
+    .mockResolvedValueOnce(initialState)
+    .mockRejectedValueOnce(new Error("final renderer state unavailable"));
+  const application = {
+    process: () => ({ pid: 424242 }),
+    close: vi.fn(async () => undefined),
+    windows: () => [],
+  };
+  const provider = new PlaywrightElectronActiveProvider(
+    {},
+    async () =>
+      application as unknown as Awaited<
+        ReturnType<typeof import("playwright-core")._electron.launch>
+      >,
+  );
+
+  const result = await provider.capture({
+    ...electronActiveObservationInputSchema.parse({
+      executable_path: process.execPath,
+      application_path: process.execPath,
+      actions: [],
+    }),
+    application_root: dirname(process.execPath),
+  });
+
+  expect(result.ok).toBe(false);
+  if (result.ok) throw new Error("Expected final state capture to fail");
+  const partialObservation = result.error.partialObservation;
+  expect(partialObservation).toMatchObject({
+    kind: "electron-active-observation",
+    capture: {
+      application: { electron_version: "44.0.0" },
+      limitations: expect.arrayContaining([
+        expect.stringContaining("initial pre-action snapshot"),
+      ]),
+    },
+  });
+});
diff --git a/src/browser/PlaywrightElectronActiveProvider.ts b/src/browser/PlaywrightElectronActiveProvider.ts
index 816f864890..68c8513524 100644
--- a/src/browser/PlaywrightElectronActiveProvider.ts
+++ b/src/browser/PlaywrightElectronActiveProvider.ts
@@ -145,11 +145,7 @@ export class PlaywrightElectronActiveProvider implements ElectronActiveObservati
           )
         : ok(capture);
     } catch (cause: unknown) {
-      if (
-        options.signal?.aborted &&
-        paths !== undefined &&
-        initialState !== undefined
-      ) {
+      if (paths !== undefined && initialState !== undefined) {
         const retainedCapture = projectElectronActiveCapture(
           paths,
           actions,
@@ -159,25 +155,33 @@ export class PlaywrightElectronActiveProvider implements ElectronActiveObservati
           ...retainedCapture,
           limitations: [
             ...retainedCapture.limitations,
-            `Final Electron state was unavailable after cancellation: ${cause instanceof Error ? cause.message : String(cause)}. Windows, metrics, IPC, and timeline are the snapshot collected before actions and may omit their effects.`,
+            `Capture stopped after the initial pre-action snapshot: ${cause instanceof Error ? cause.message : String(cause)}. Final Windows, metrics, IPC, and timeline state is unknown; the retained snapshot may omit action effects.`,
           ],
         };
       }
-      outcome = err(
-        options.signal?.aborted === true
-          ? new BrowserObservationError(OPERATION, "cancelled", {
-              cause,
-              ...(capture === undefined
-                ? {}
-                : {
-                    partialObservation: {
-                      kind: "electron-active-observation" as const,
-                      capture,
-                    },
-                  }),
-            })
-          : providerError(cause),
-      );
+      if (options.signal?.aborted === true)
+        outcome = err(
+          new BrowserObservationError(OPERATION, "cancelled", {
+            cause,
+            ...(capture === undefined
+              ? {}
+              : {
+                  partialObservation: {
+                    kind: "electron-active-observation" as const,
+                    capture,
+                  },
+                }),
+          }),
+        );
+      else {
+        const error = providerError(cause);
+        if (capture !== undefined)
+          error.retainPartialObservation({
+            kind: "electron-active-observation",
+            capture,
+          });
+        outcome = err(error);
+      }
     }
     if (application !== undefined) {
       if (ownership !== undefined) {
diff --git a/src/browser/WebSourceMapFetcher.ts b/src/browser/WebSourceMapFetcher.ts
index 4ab805f43a..0148cb9a29 100644
--- a/src/browser/WebSourceMapFetcher.ts
+++ b/src/browser/WebSourceMapFetcher.ts
@@ -11,6 +11,10 @@ import { isUrlLikeModuleSpecifier } from "../domain/webBundleAnalyzerAst.js";
 import { analyzeParsedJavaScriptReferences } from "../domain/javascript/javascriptSemanticAnalysis.js";
 import { traverseJavaScriptAst } from "../domain/javascript/javascriptSemanticTraversal.js";
 import { parseJavaScriptSource } from "../domain/javascript/javascriptSourceParser.js";
+import {
+  isTypeOnlyExportDeclaration,
+  isTypeOnlyImportDeclaration,
+} from "../domain/javascript/javascriptModuleDeclaration.js";
 import { stringValue } from "../domain/javascript/javascriptStaticAnalysisHelpers.js";
 import type {
   AnalyzeWebBundleInput,
@@ -1061,7 +1065,11 @@ const originalDependency = (
     t.isExportAllDeclaration(node) ||
     t.isExportNamedDeclaration(node)
   )
-    return node.source === null || node.source === undefined
+    return node.source === null ||
+      node.source === undefined ||
+      (t.isImportDeclaration(node)
+        ? isTypeOnlyImportDeclaration(node)
+        : isTypeOnlyExportDeclaration(node))
       ? null
       : { kind: "static_import", specifier: node.source.value };
   if (t.isImportExpression(node)) {
diff --git a/src/domain/webCaptureDiff.ts b/src/domain/webCaptureDiff.ts
index ba23228b11..39e88e6d6a 100644
--- a/src/domain/webCaptureDiff.ts
+++ b/src/domain/webCaptureDiff.ts
@@ -333,6 +333,13 @@ const networkDimension = (
   );
   const beforeWebSockets = webSocketGroups(before);
   const afterWebSockets = webSocketGroups(after);
+  const inventoryComplete = [before, after].every((inspection) =>
+    sectionsComplete(inspection, [
+      "network_requests",
+      "websocket_connections",
+      "websocket_frames",
+    ]),
+  );
   const [beforeWebSocketPayload, afterWebSocketPayload] = webSocketPayloadMaps(
     beforeWebSockets,
     afterWebSockets,
@@ -349,17 +356,12 @@ const networkDimension = (
       ...webSocketMetadataMap(afterWebSockets),
       ...afterWebSocketPayload,
     ]),
-    [before, after].every((inspection) =>
-      sectionsComplete(inspection, [
-        "network_requests",
-        "websocket_connections",
-        "websocket_frames",
-      ]),
-    ) &&
+    inventoryComplete &&
       shapesComplete &&
       webSocketPayloadBytesComplete &&
       webSocketShapesComplete,
     "Network capture or selected HTTP/WebSocket payload-shape coverage is attach-window limited, unavailable, or incomplete.",
+    inventoryComplete,
   );
   return compared.status === "unchanged" && !responseFieldsComplete
     ? {
diff --git a/tests/boundary/browser/cdpConnection.test.ts b/tests/boundary/browser/cdpConnection.test.ts
index 993a44e6d6..71ef6a2456 100644
--- a/tests/boundary/browser/cdpConnection.test.ts
+++ b/tests/boundary/browser/cdpConnection.test.ts
@@ -28,6 +28,7 @@ const INVALID_REPLIES = [
     }),
   ],
   ["invalid result", (id: number) => ({ id, result: [] })],
+  ["missing session id", (id: number) => ({ id, result: {} })],
   ["invalid session id", (id: number) => ({ id, result: {}, sessionId: 7 })],
   [
     "foreign session id",
diff --git a/tests/boundary/browser/cdpDomSvgIdentity.test.ts b/tests/boundary/browser/cdpDomSvgIdentity.test.ts
index 7d42ae3366..eeaebf2e7a 100644
--- a/tests/boundary/browser/cdpDomSvgIdentity.test.ts
+++ b/tests/boundary/browser/cdpDomSvgIdentity.test.ts
@@ -254,6 +254,7 @@ describe("CDP SVG query concurrency", () => {
           browser.emitRawMessage(
             JSON.stringify({
               id: command.id,
+              sessionId: command.sessionId,
               result: {
                 node: {
                   backendNodeId: id,
@@ -295,6 +296,7 @@ describe("CDP SVG query concurrency", () => {
       browser.emitRawMessage(
         JSON.stringify({
           id: batch.at(-1)?.id,
+          sessionId: batch.at(-1)?.sessionId,
           error: { code: -32_602, message: "Invalid parameters" },
         }),
       );
diff --git a/tests/boundary/browser/cdpElectronProvider.test.ts b/tests/boundary/browser/cdpElectronProvider.test.ts
index f115846109..307f4cbbf6 100644
--- a/tests/boundary/browser/cdpElectronProvider.test.ts
+++ b/tests/boundary/browser/cdpElectronProvider.test.ts
@@ -258,7 +258,62 @@ describe("CdpElectronProvider packaged pages", () => {
   });
 });
 
-describe("CdpElectronProvider capture", () => {
+describe("CdpElectronProvider frame capture", () => {
+  it.each([7, undefined])(
+    "reports a malformed child frame ID as unavailable protocol evidence: %s",
+    async (childId) => {
+      const root = await electronFixture();
+      const main = pathToFileURL(join(root, "index.html")).href;
+      const child = pathToFileURL(join(root, "child.html")).href;
+      const browser = await startFakeCdpBrowser({
+        electronFileUrl: main,
+        commandResult: (command) =>
+          command.method === "Page.getFrameTree"
+            ? {
+                frameTree: {
+                  frame: { id: "frame-main", url: main },
+                  childFrames: [
+                    {
+                      frame: {
+                        ...(childId === undefined ? {} : { id: childId }),
+                        url: child,
+                      },
+                    },
+                  ],
+                },
+              }
+            : undefined,
+      });
+      browsers.push(browser);
+      const result = await new CdpElectronProvider().inspectPage(
+        inspectElectronPageInputSchema.parse({
+          cdp_endpoint: browser.endpoint,
+          target_id: "electron-page",
+          observation_ms: 0,
+        }),
+      );
+
+      if (!result.ok) throw result.error;
+      expect(result.value.frames.map((frame) => frame.frame_id)).toEqual([
+        "frame-main",
+      ]);
+      expect(result.value.completeness).toMatchObject({
+        unavailable_sections: ["frames"],
+      });
+      expect(result.value.completeness.excluded).toContainEqual({
+        section: "frames",
+        reason: "invalid_protocol_value",
+        count: 1,
+      });
+      expect(result.value.completeness.policy_filtered_sections).not.toContain(
+        "frames",
+      );
+      expect(result.value.completeness.conditions).toContain("attach_limited");
+    },
+  );
+});
+
+describe("CdpElectronProvider malformed source replies", () => {
   it.each([{}, { scriptSource: null }, { scriptSource: 123 }])(
     "rejects malformed Electron source replies instead of inventing source: %j",
     async (reply) => {
@@ -291,7 +346,9 @@ describe("CdpElectronProvider capture", () => {
       );
     },
   );
+});
 
+describe("CdpElectronProvider script source capture", () => {
   it("retains an explicitly empty Electron producer script", async () => {
     const root = await electronFixture();
     const browser = await startFakeCdpBrowser({
diff --git a/tests/boundary/browser/cdpScreenshotDocumentIdentity.test.ts b/tests/boundary/browser/cdpScreenshotDocumentIdentity.test.ts
index b3fcbc592e..b768485989 100644
--- a/tests/boundary/browser/cdpScreenshotDocumentIdentity.test.ts
+++ b/tests/boundary/browser/cdpScreenshotDocumentIdentity.test.ts
@@ -3,6 +3,30 @@ import { CdpBrowserProvider } from "../../../src/browser/CdpBrowserProvider.js";
 import { captureWebScreenshotInputSchema } from "../../../src/domain/webScreenshot.js";
 import { startFakeCdpBrowser } from "../../fixtures/fakeCdpBrowser.js";
 describe("screenshot committed document identity", () => {
+  it.each([
+    ["missing screenshot data", {}],
+    ["invalid base64 screenshot data", { data: "not base64%%%" }],
+  ])("reports %s as a protocol error", async (_label, result) => {
+    const browser = await startFakeCdpBrowser({
+      commandResult: ({ method }) =>
+        method === "Page.captureScreenshot" ? result : undefined,
+    });
+    onTestFinished(async () => {
+      await browser.close();
+    });
+    const observation = await new CdpBrowserProvider().captureScreenshot(
+      captureWebScreenshotInputSchema.parse({
+        cdp_endpoint: browser.endpoint,
+        allowed_origins: [browser.allowedOrigin],
+        target_id: "allowed-page",
+      }),
+    );
+    expect(observation).toMatchObject({
+      ok: false,
+      error: { reason: "protocol_error" },
+    });
+  });
+
   it.each([
     { offset: 8, value: 14 },
     { offset: 16, value: 0x8000_0000 },
diff --git a/tests/boundary/browser/webCaptureDiff.test.ts b/tests/boundary/browser/webCaptureDiff.test.ts
index 4d372650e3..11d992fa4d 100644
--- a/tests/boundary/browser/webCaptureDiff.test.ts
+++ b/tests/boundary/browser/webCaptureDiff.test.ts
@@ -684,6 +684,44 @@ describe("web capture WebSocket payload byte coverage", () => {
 });
 
 describe("web capture diff", () => {
+  it("reports request membership changes when selected body shapes are unavailable", async () => {
+    const browser = await startFakeCdpBrowser();
+    browsers.push(browser);
+    const captured = await new CdpBrowserProvider().inspectPage(
+      inspectWebPageInputSchema.parse({
+        cdp_endpoint: browser.endpoint,
+        allowed_origins: [browser.allowedOrigin],
+        target_id: "allowed-page",
+        observation_ms: 0,
+      }),
+    );
+    if (!captured.ok) throw captured.error;
+    const before = structuredClone(captured.value);
+    const after = structuredClone(captured.value);
+    const original = before.network.requests[0];
+    if (original === undefined) throw new Error("Missing request fixture");
+    after.network.requests.push({
+      ...structuredClone(original),
+      request_id: `${original.request_id}-added`,
+      url: `${browser.allowedOrigin}/added`,
+    });
+    for (const inspection of [before, after]) {
+      markSectionsComplete(inspection, [
+        "network_requests",
+        "websocket_connections",
+        "websocket_frames",
+      ]);
+      for (const request of inspection.network.requests)
+        request.body_shapes.status = "unavailable";
+    }
+
+    expect(compareNetwork(before, after)).toMatchObject({
+      status: "changed",
+      total_changes: 1,
+      changes: [expect.objectContaining({ change: "added" })],
+    });
+  });
+
   it.each(["status", "mime_type"] as const)(
     "keeps an independently unavailable HTTP %s unknown",
     async (field) => {
diff --git a/tests/boundary/browser/webSourceMapFetcher.test.ts b/tests/boundary/browser/webSourceMapFetcher.test.ts
index 84ef1506fe..782ff8cf07 100644
--- a/tests/boundary/browser/webSourceMapFetcher.test.ts
+++ b/tests/boundary/browser/webSourceMapFetcher.test.ts
@@ -1102,6 +1102,21 @@ describe("source-map dependency coverage of hard-to-parse sources", () => {
       'import lib = require("./lib.js");',
       ["./lib.js"],
     ],
+    [
+      "whole-statement type-only import",
+      'import type { Value } from "./types.js";',
+      [],
+    ],
+    [
+      "whole-statement type-only export",
+      'export type { Value } from "./types.js";',
+      [],
+    ],
+    [
+      "inline type import retains module side effects",
+      'import { type Value } from "./types.js";',
+      ["./types.js"],
+    ],
     [
       "a local import alias",
       'import lib = localAlias;\nimport "./a.js";',
diff --git a/tests/fixtures/fakeCdpBrowser.ts b/tests/fixtures/fakeCdpBrowser.ts
index aa476a58b0..37e59b77b6 100644
--- a/tests/fixtures/fakeCdpBrowser.ts
+++ b/tests/fixtures/fakeCdpBrowser.ts
@@ -31,44 +31,9 @@ export const startFakeCdpBrowser = async (
   let openedConnections = 0;
   let frameTreeReads = 0;
   let port = 0;
-  const http = createServer((request, response) => {
-    httpRequests.push({
-      url: request.url ?? "",
-      authorization: request.headers.authorization,
-      cookie: request.headers.cookie,
-      referer: request.headers.referer,
-    });
-    response.setHeader("content-type", "application/json");
-    if (serveSourceMap(request, response, options)) return;
-    if (request.url === "/json/version") {
-      response.end(
-        options.oversizedDiscovery === true
-          ? " ".repeat(65 * 1_024)
-          : options.malformedDiscovery === true
-            ? "{not-json"
-            : JSON.stringify({
-                Browser: "FakeChrome/1.0",
-                "Protocol-Version": "1.3",
-                "User-Agent": "FakeChrome",
-                "V8-Version": "13.0",
-                "WebKit-Version": "fake-revision",
-                webSocketDebuggerUrl:
-                  options.invalidBrowserWebSocket === true
-                    ? `ws://localhost:${String(port)}/devtools/invalid/fake`
-                    : options.pageScopedVersionWebSocket === true
-                      ? `ws://localhost:${String(port)}/devtools/page/${versionTargetId(options)}`
-                      : `ws://localhost:${String(port)}/devtools/browser/fake`,
-              }),
-      );
-      return;
-    }
-    if (request.url === "/json/list") {
-      response.end(JSON.stringify(targets(port, options)));
-      return;
-    }
-    response.statusCode = 404;
-    response.end("{}");
-  });
+  const http = createServer((request, response) =>
+    respondToHttpRequest(request, response, httpRequests, options, () => port),
+  );
   const webSockets = new WebSocketServer({ noServer: true });
   http.on("upgrade", (request, socket, head) => {
     if (
@@ -94,7 +59,7 @@ export const startFakeCdpBrowser = async (
       commands.push(command);
       const commandError = options.commandError?.(command);
       if (commandError !== undefined) {
-        socket.send(JSON.stringify({ id: command.id, error: commandError }));
+        sendCommandReply(socket, command, { error: commandError });
         return;
       }
       if (options.closeOnMethod === command.method) {
@@ -107,12 +72,9 @@ export const startFakeCdpBrowser = async (
         return;
       }
       if (options.unsupportedMethods?.includes(command.method) === true) {
-        socket.send(
-          JSON.stringify({
-            id: command.id,
-            error: { code: -32_601, message: "Method not found" },
-          }),
-        );
+        sendCommandReply(socket, command, {
+          error: { code: -32_601, message: "Method not found" },
+        });
         return;
       }
       if (
@@ -120,12 +82,9 @@ export const startFakeCdpBrowser = async (
         (command.method === "Target.attachToTarget" ||
           command.sessionId !== undefined)
       ) {
-        socket.send(
-          JSON.stringify({
-            id: command.id,
-            error: { code: -32_600, message: "Direct page socket expected" },
-          }),
-        );
+        sendCommandReply(socket, command, {
+          error: { code: -32_600, message: "Direct page socket expected" },
+        });
         return;
       }
       if (command.method === "Page.getFrameTree") frameTreeReads += 1;
@@ -164,6 +123,57 @@ export const startFakeCdpBrowser = async (
   };
 };
 
+const respondToHttpRequest = (
+  request: IncomingMessage,
+  response: ServerResponse,
+  requests: {
+    url: string;
+    authorization: string | undefined;
+    cookie: string | undefined;
+    referer: string | undefined;
+  }[],
+  options: FakeOptions,
+  port: () => number,
+): void => {
+  requests.push({
+    url: request.url ?? "",
+    authorization: request.headers.authorization,
+    cookie: request.headers.cookie,
+    referer: request.headers.referer,
+  });
+  response.setHeader("content-type", "application/json");
+  const portNumber = port();
+  if (serveSourceMap(request, response, options)) return;
+  if (request.url === "/json/version") {
+    response.end(
+      options.oversizedDiscovery === true
+        ? " ".repeat(65 * 1_024)
+        : options.malformedDiscovery === true
+          ? "{not-json"
+          : JSON.stringify({
+              Browser: "FakeChrome/1.0",
+              "Protocol-Version": "1.3",
+              "User-Agent": "FakeChrome",
+              "V8-Version": "13.0",
+              "WebKit-Version": "fake-revision",
+              webSocketDebuggerUrl:
+                options.invalidBrowserWebSocket === true
+                  ? `ws://localhost:${String(portNumber)}/devtools/invalid/fake`
+                  : options.pageScopedVersionWebSocket === true
+                    ? `ws://localhost:${String(portNumber)}/devtools/page/${versionTargetId(options)}`
+                    : `ws://localhost:${String(portNumber)}/devtools/browser/fake`,
+            }),
+    );
+    return;
+  }
+  if (request.url === "/json/list") {
+    response.end(JSON.stringify(targets(portNumber, options)));
+    return;
+  }
+  response.statusCode = 404;
+  response.end("{}");
+};
+
 const boundPort = (
   address: string | null | { readonly port: number },
 ): number => {
@@ -172,6 +182,25 @@ const boundPort = (
   return address.port;
 };
 
+/** Every ordinary reply uses the request's flattened target session. */
+const sendCommandReply = (
+  socket: WebSocket,
+  command: FakeCdpCommand,
+  payload:
+    | { readonly result: unknown }
+    | { readonly error: { readonly code: number; readonly message: string } },
+): void => {
+  socket.send(
+    JSON.stringify({
+      id: command.id,
+      ...(command.sessionId === undefined
+        ? {}
+        : { sessionId: command.sessionId }),
+      ...payload,
+    }),
+  );
+};
+
 /** Emit a configured producer reply and its associated events. */
 const replyToCommand = (
   socket: WebSocket,
@@ -187,24 +216,16 @@ const replyToCommand = (
       frameTreeReads,
     ) ?? resultFor(command, port, options, frameTreeReads);
   if (result === undefined) {
-    socket.send(
-      JSON.stringify({
-        id: command.id,
-        error: {
-          code: -32_601,
-          message: `Method not found: ${command.method}`,
-        },
-      }),
-    );
+    sendCommandReply(socket, command, {
+      error: {
+        code: -32_601,
+        message: `Method not found: ${command.method}`,
+      },
+    });
     return;
   }
   const reply = () => {
-    socket.send(
-      JSON.stringify({
-        id: command.id,
-        result,
-      }),
-    );
+    sendCommandReply(socket, command, { result });
     if (options.malformedEventOnMethod === command.method)
       socket.send("{not-json");
     if (options.malformedEventShapeOnMethod === command.method)