diff --git a/src/domain/javascript/javascriptSemanticAnalysis.runtime_boundaries.test.ts b/src/domain/javascript/javascriptSemanticAnalysis.runtime_boundaries.test.ts
index 792b8a0ea3..4ee17e8b25 100644
--- a/src/domain/javascript/javascriptSemanticAnalysis.runtime_boundaries.test.ts
+++ b/src/domain/javascript/javascriptSemanticAnalysis.runtime_boundaries.test.ts
@@ -73,6 +73,23 @@ describe("JavaScript semantic analysis: runtime boundaries 1", () => {
     ]);
   });
 
+  it("keeps an overflowing timer delay unknown in a complete semantic result", () => {
+    const ir = analyzeJavaScriptSemantics(`
+      function greet() { return "hello"; }
+      setTimeout(() => greet(), 1e999);
+    `);
+
+    expect(ir.timerOperations).toEqual([
+      expect.objectContaining({
+        kind: "schedule",
+        method: "setTimeout",
+        delayMilliseconds: null,
+        resolution: "complete",
+      }),
+    ]);
+    expect(ir.callables.some(({ name }) => name === "greet")).toBe(true);
+  });
+
   it("does not treat shadowed timer globals as Node timers", () => {
     const ir = analyzeJavaScriptSemantics(`
       function run(setTimeout, clearTimeout) {
diff --git a/src/domain/javascript/javascriptSemanticAsyncEffects.ts b/src/domain/javascript/javascriptSemanticAsyncEffects.ts
index 97a2d03b34..99fe538738 100644
--- a/src/domain/javascript/javascriptSemanticAsyncEffects.ts
+++ b/src/domain/javascript/javascriptSemanticAsyncEffects.ts
@@ -368,7 +368,11 @@ const timerDelay = (candidate: TimerCandidate): number | null => {
   if (candidate.kind !== "schedule" || candidate.method === "setImmediate")
     return null;
   const delay = candidate.node.arguments[1];
-  return t.isNumericLiteral(delay) ? delay.value : null;
+  // An overflowing literal such as 1e999 parses to Infinity, which JSON
+  // Evidence cannot carry; keep that delay unknown like any other.
+  return t.isNumericLiteral(delay) && Number.isFinite(delay.value)
+    ? delay.value
+    : null;
 };
 
 const timerId = (candidate: TimerCandidate): string =>
diff --git a/tests/boundary/mcp/javascriptTimerDelay.test.ts b/tests/boundary/mcp/javascriptTimerDelay.test.ts
new file mode 100644
index 0000000000..71af083487
--- /dev/null
+++ b/tests/boundary/mcp/javascriptTimerDelay.test.ts
@@ -0,0 +1,109 @@
+import { Client } from "@modelcontextprotocol/client";
+import { StdioClientTransport } from "@modelcontextprotocol/client/stdio";
+import { createHash } from "node:crypto";
+import { readFile, writeFile } from "node:fs/promises";
+import { join, resolve } from "node:path";
+import { expect } from "vitest";
+
+import { toolContract } from "../../../src/contracts/toolContracts.js";
+import { javascriptApplicationAnalysisResultSchema } from "../../../src/domain/javascript/javascriptApplicationAnalysis.js";
+import { createTestTempDirectory } from "../../fixtures/temporaryDirectory.js";
+import { cliTest } from "../../support/cli/cliFixture.js";
+
+cliTest(
+  "retains unknown timer delays and unrelated facts through public CLI and MCP",
+  { timeout: 60_000 },
+  async ({ cli }) => {
+    const root = await createTestTempDirectory("rea-timer-delay-");
+    const source = [
+      'export function greet() { return "hello"; }',
+      "setTimeout(() => greet(), 1e999);",
+      "setInterval(() => greet(), 1e309);",
+      "setTimeout(() => greet(), 100);",
+      "setTimeout(() => greet(), 1e308);",
+      "setTimeout(() => greet(), Infinity);",
+      "setImmediate(() => greet());",
+    ].join("\n");
+    const path = join(root, "main.js");
+    await writeFile(path, source);
+    const digest = createHash("sha256").update(source).digest("hex");
+    const cliResult = await cli.run({
+      arguments: ["analyze-javascript-application", root, "--json"],
+    });
+    expect(cliResult.exitCode).toBe(0);
+    const contract = toolContract("analyze_javascript_application");
+    const cliEvidence = contract.outputSchema.parse(cliResult.json);
+    const graph = javascriptApplicationAnalysisResultSchema.parse(
+      cliEvidence.normalized_result,
+    ).semantic_graph;
+    const timers = graph.nodes.filter(({ kind }) => kind === "timer");
+    const pairs = timers.map(({ properties }) => [
+      properties.method,
+      properties.delay_milliseconds,
+    ]);
+    const sorted = (values: unknown[]) =>
+      values.map((value) => JSON.stringify(value)).sort();
+    expect(sorted(pairs)).toEqual(
+      sorted([
+        ["setTimeout", null],
+        ["setInterval", null],
+        ["setTimeout", 100],
+        ["setTimeout", 1e308],
+        ["setTimeout", null],
+        ["setImmediate", null],
+      ]),
+    );
+    expect(
+      graph.nodes.find(
+        ({ kind, label }) => kind === "function" && label === "greet",
+      )?.identity,
+    ).toMatchObject({ module_path: "main.js", artifact_sha256: digest });
+    for (const timer of timers) {
+      expect(Object.hasOwn(timer.properties, "delay_milliseconds")).toBe(true);
+      expect(timer.identity).toMatchObject({
+        module_path: "main.js",
+        artifact_sha256: digest,
+      });
+    }
+
+    const client = new Client({ name: "timer-delay-boundary", version: "1" });
+    const transport = new StdioClientTransport({
+      command: process.execPath,
+      args: [resolve("scripts/rea.mjs"), "mcp"],
+      cwd: process.cwd(),
+      env: { PATH: process.env.PATH ?? "" },
+      stderr: "pipe",
+    });
+    transport.stderr?.on("data", () => undefined);
+    try {
+      await client.connect(transport);
+      const reply = await client.callTool({
+        name: contract.name,
+        arguments: { input_path: root },
+      });
+      expect(reply.isError).not.toBe(true);
+      const evidence = contract.outputSchema.parse(reply.structuredContent);
+      expect(evidence.evidence_id).toBe(cliEvidence.evidence_id);
+      const text = reply.content.find((item) => item.type === "text");
+      if (text?.type !== "text") throw new Error("Missing inline Evidence");
+      expect(
+        contract.outputSchema.parse(JSON.parse(text.text)).evidence_id,
+      ).toBe(evidence.evidence_id);
+      const retained = javascriptApplicationAnalysisResultSchema.parse(
+        evidence.normalized_result,
+      ).semantic_graph;
+      expect(retained.nodes.filter(({ kind }) => kind === "timer")).toEqual(
+        timers,
+      );
+      expect(
+        retained.nodes.some(
+          ({ kind, label }) => kind === "function" && label === "greet",
+        ),
+      ).toBe(true);
+      await expect(client.ping()).resolves.toEqual({});
+    } finally {
+      await Promise.all([client.close(), transport.close()]);
+    }
+    expect(await readFile(path, "utf8")).toBe(source);
+  },
+);