diff --git a/src/cliJsonInput.ts b/src/cliJsonInput.ts
index 5c4397bf64..74dd30bc9c 100644
--- a/src/cliJsonInput.ts
+++ b/src/cliJsonInput.ts
@@ -1,10 +1,14 @@
+import { constants as bufferConstants } from "node:buffer";
 import { resolve } from "node:path";
 
 import {
   NonRegularFileReadError,
   readRegularFile,
 } from "./application/RegularFileRead.js";
-import { AnalysisInputError } from "./domain/analysisErrorCore.js";
+import {
+  AnalysisInputError,
+  AnalysisResourceConstraintError,
+} from "./domain/analysisErrorCore.js";
 import { projectAnalysisError } from "./domain/analysisErrorProjection.js";
 import type { JsonValue } from "./domain/jsonValue.js";
 import { safeParseJson } from "./domain/safeJson.js";
@@ -18,14 +22,16 @@ export const parseCliJsonInput = async (
   | { readonly ok: false; readonly error: JsonValue }
 > => {
   const inline = parseJson(value);
-  if (inline !== undefined) return { ok: true, value: inline };
+  if (inline.kind === "valid") return { ok: true, value: inline.value };
+  if (inline.kind === "too-large")
+    return jsonTooLargeError(undefined, operation);
   try {
     // Read raw bytes so invalid UTF-8 is rejected by parseJson instead of
     // being silently replaced by lossy "utf8" decoding.
     const parsed = parseJson(await readRegularFile(value));
-    return parsed === undefined
-      ? jsonFileError(value, operation, "invalid-json")
-      : { ok: true, value: parsed };
+    if (parsed.kind === "valid") return { ok: true, value: parsed.value };
+    if (parsed.kind === "too-large") return jsonTooLargeError(value, operation);
+    return jsonFileError(value, operation, "invalid-json");
   } catch (cause: unknown) {
     if (
       ["{", "["].includes(value.trimStart()[0] ?? "") &&
@@ -87,7 +93,12 @@ const cannotBeAnExistingFile = (cause: unknown): boolean =>
 const hasExplicitJsonFileExtension = (value: string): boolean =>
   value.toLowerCase().endsWith(".json");
 
-const parseJson = (value: string | Uint8Array): unknown => {
+type JsonParseResult =
+  | { readonly kind: "valid"; readonly value: unknown }
+  | { readonly kind: "invalid" }
+  | { readonly kind: "too-large" };
+
+const parseJson = (value: string | Uint8Array): JsonParseResult => {
   let text: string;
   if (typeof value === "string") {
     text = value;
@@ -98,15 +109,24 @@ const parseJson = (value: string | Uint8Array): unknown => {
         ignoreBOM: true,
       }).decode(value);
     } catch (cause: unknown) {
-      // Decoding failure means the bytes are not valid UTF-8 JSON input.
-      void cause;
-      return undefined;
+      return isStringLengthLimit(cause)
+        ? { kind: "too-large" }
+        : { kind: "invalid" };
     }
   }
   const parsed = safeParseJson(text);
-  return parsed.ok ? parsed.value : undefined;
+  if (parsed.ok) return { kind: "valid", value: parsed.value };
+  return isStringLengthLimit(parsed.cause)
+    ? { kind: "too-large" }
+    : { kind: "invalid" };
 };
 
+const isStringLengthLimit = (cause: unknown): boolean =>
+  cause instanceof Error &&
+  /cannot create a string longer than|invalid string length/i.test(
+    cause.message,
+  );
+
 const inputError = (operation: string): JsonValue => ({
   error: "Application workflow failed",
   ...projectAnalysisError(
@@ -157,3 +177,33 @@ const readFailureIssue = (path: string | undefined, cause: unknown) => {
         : `The JSON input file could not be read${code}: ${path ?? ""}`,
   };
 };
+
+const jsonTooLargeError = (
+  path: string | undefined,
+  operation: string,
+): { readonly ok: false; readonly error: JsonValue } => {
+  const projection = projectAnalysisError(
+    new AnalysisResourceConstraintError(
+      operation,
+      "memory",
+      `The JSON input exceeds this Node.js runtime's maximum string length (${bufferConstants.MAX_STRING_LENGTH} UTF-16 code units) and cannot be parsed as one value.`,
+      {
+        boundary: "cli-json-input",
+        max_string_code_units: bufferConstants.MAX_STRING_LENGTH,
+      },
+      {
+        remediationAction:
+          "Split the JSON into smaller inputs or rerun its producer on a smaller subset, then retry.",
+      },
+    ),
+  );
+  return {
+    ok: false,
+    error: {
+      error: "Application workflow failed",
+      ...projection,
+      ...(path === undefined ? {} : { input_path: path }),
+      input_reason: "too-large",
+    },
+  };
+};
diff --git a/src/contracts/errorSchemas.ts b/src/contracts/errorSchemas.ts
index a535f6abf2..812dc89d62 100644
--- a/src/contracts/errorSchemas.ts
+++ b/src/contracts/errorSchemas.ts
@@ -73,7 +73,9 @@ export const analysisCliErrorEnvelopeSchema = z
   .object({
     error: z.string().min(1),
     input_path: z.string().optional(),
-    input_reason: z.enum(["invalid-json", "read-failed"]).optional(),
+    input_reason: z
+      .enum(["invalid-json", "read-failed", "too-large"])
+      .optional(),
   })
   .passthrough()
   .superRefine((value, context) => {
diff --git a/tests/boundary/filesystem/cliJsonInput.test.ts b/tests/boundary/filesystem/cliJsonInput.test.ts
index d75dac4e3d..273168fdbe 100644
--- a/tests/boundary/filesystem/cliJsonInput.test.ts
+++ b/tests/boundary/filesystem/cliJsonInput.test.ts
@@ -1,11 +1,20 @@
 import { execFile } from "node:child_process";
-import { chmod, symlink, writeFile } from "node:fs/promises";
+import { constants as bufferConstants } from "node:buffer";
+import {
+  chmod,
+  open,
+  symlink,
+  type FileHandle,
+  writeFile,
+} from "node:fs/promises";
 import { join } from "node:path";
 import { promisify } from "node:util";
 
 import { describe, expect, it, onTestFinished } from "vitest";
 
+import { isCliOperationFailure } from "../../../src/cliLogging.js";
 import { parseCliJsonInput } from "../../../src/cliJsonInput.js";
+import { analysisCliErrorEnvelopeSchema } from "../../../src/contracts/errorSchemas.js";
 import { readWithoutFifoWriter } from "../../fixtures/fifoInput.js";
 import { createTestTempDirectory } from "../../fixtures/temporaryDirectory.js";
 
@@ -85,6 +94,51 @@ describe("CLI JSON file selection", () => {
 });
 
 describe("CLI JSON input", () => {
+  it("reports a valid file beyond the runtime string limit as too large", async () => {
+    const root = await createTestTempDirectory("rea-json-input-too-large-");
+    const path = join(root, "input.json");
+    const size = bufferConstants.MAX_STRING_LENGTH + 1;
+    await writeValidOversizedObject(path, size);
+
+    const result = await parseCliJsonInput(path, "test-input");
+    if (result.ok) throw new Error("Expected oversized JSON to be rejected");
+    expect(analysisCliErrorEnvelopeSchema.parse(result.error)).toEqual(
+      result.error,
+    );
+    expect(result).toMatchObject({
+      ok: false,
+      error: {
+        code: "resource_constraint",
+        input_path: path,
+        input_reason: "too-large",
+        details: {
+          resource: "memory",
+          reported_limits: {
+            boundary: "cli-json-input",
+            max_string_code_units: bufferConstants.MAX_STRING_LENGTH,
+          },
+        },
+        remediation: {
+          action:
+            "Split the JSON into smaller inputs or rerun its producer on a smaller subset, then retry.",
+        },
+      },
+    });
+
+    expect(isCliOperationFailure(result.error)).toBe(true);
+
+    const characterCount =
+      Math.floor(bufferConstants.MAX_STRING_LENGTH / 2) + 2;
+    await writeValidMultibyteString(path, characterCount);
+
+    const multibyteResult = await parseCliJsonInput(path, "test-input");
+    if (!multibyteResult.ok)
+      throw new Error("Expected large multibyte JSON to fit the string limit");
+    if (typeof multibyteResult.value !== "string")
+      throw new Error("Expected parsed JSON string");
+    expect(multibyteResult.value.length).toBe(characterCount);
+  }, 20_000);
+
   it("distinguishes malformed inline text from files and preserves bracket-prefixed paths", async () => {
     expect(await parseCliJsonInput("[", "test-input")).toMatchObject({
       ok: false,
@@ -177,3 +231,47 @@ describe("CLI JSON input", () => {
     },
   );
 });
+
+const writeRepeatedBytes = async (
+  handle: FileHandle,
+  bytes: Buffer,
+  length: number,
+): Promise<void> => {
+  let remaining = length;
+  while (remaining > 0) {
+    const chunkLength = Math.min(bytes.length, remaining);
+    await handle.writeFile(bytes.subarray(0, chunkLength));
+    remaining -= chunkLength;
+  }
+};
+
+const writeValidOversizedObject = async (
+  path: string,
+  size: number,
+): Promise<void> => {
+  const handle = await open(path, "w");
+  const whitespace = Buffer.alloc(1024 * 1024, 0x20);
+  try {
+    await handle.writeFile("{");
+    await writeRepeatedBytes(handle, whitespace, size - 2);
+    await handle.writeFile("}");
+  } finally {
+    await handle.close();
+  }
+};
+
+const writeValidMultibyteString = async (
+  path: string,
+  characterCount: number,
+): Promise<void> => {
+  const encodedCharacters = Buffer.from("é".repeat(512 * 1024));
+  const byteLength = characterCount * 2 + 2;
+  const handle = await open(path, "w");
+  try {
+    await handle.writeFile('"');
+    await writeRepeatedBytes(handle, encodedCharacters, byteLength - 2);
+    await handle.writeFile('"');
+  } finally {
+    await handle.close();
+  }
+};