diff --git a/docs/cli.md b/docs/cli.md
index dd557703a6..efed8a8bea 100644
--- a/docs/cli.md
+++ b/docs/cli.md
@@ -383,7 +383,8 @@ readable by their owner only, since they hold captured content) with
 smoke task `tasks/smoke.json`. `--package-tarball` copies a packed `rea-agents`
 tarball into the env folder and installs it instead of the registry package,
 which is how the hosted lane proves a checkout rather than a release. `--name`
-replaces the manifest's kebab-case name as the env folder and env id. The
+replaces the manifest's kebab-case name as the env folder and env id; a device
+name Windows reserves (`con`, `nul`, `com1` and the like) is refused. The
 command prints one JSON document listing the written files with their sizes
 and the pinned package source. See
 [agent environments](agent-environments.md#export-a-bundle) for the folder
@@ -438,7 +439,8 @@ error and exit `1`, as does a listener that fails after binding.
 `rea environment-export` is one-shot: it prints the written files and exits
 `0`, or prints a structured `invalid_request` error and exits `1` for the same
 pair refusals, a non-empty or file-occupied directory, a missing package
-tarball or a name that is not a kebab-case label, writing nothing in each case.
+tarball or a name that is not a kebab-case label or is a Windows device name,
+writing nothing in each case.
 A write that fails after the first file (a permission or disk-space failure
 on a later path) propagates as the host's failure and leaves the partial
 folder in place for inspection; remove it before retrying, since the next
diff --git a/docs/specs/agent-environments/environment-export/spec.md b/docs/specs/agent-environments/environment-export/spec.md
index 90a7feb5f7..f150f86112 100644
--- a/docs/specs/agent-environments/environment-export/spec.md
+++ b/docs/specs/agent-environments/environment-export/spec.md
@@ -33,7 +33,9 @@ previous increment.
   copies of the inputs (mode `0600`, so captured content stays readable by its
   owner only whatever the umask), `artifacts/check_<name>/verify.py` and
   `tasks/smoke.json`, where `<name>` defaults to the manifest's kebab-case name
-  and `--name` must be a kebab-case label of at most 64 characters.
+  and `--name` must be a kebab-case label of at most 64 characters that is not a
+  device name Windows reserves (`con`, `prn`, `aux`, `nul`, `com1`–`com9`,
+  `lpt1`–`lpt9`), since the env folder could not be created there.
 - The Dockerfile reads `FROM node:24.18.0-bookworm-slim`, sets
   `MCP_HOST=0.0.0.0` and `MCP_PORT=18765`, installs Debian's `python3` for the
   framework's readiness probe, installs
diff --git a/src/application/JsonInputFile.ts b/src/application/JsonInputFile.ts
index 29ac051ffc..2e93d0a679 100644
--- a/src/application/JsonInputFile.ts
+++ b/src/application/JsonInputFile.ts
@@ -35,16 +35,19 @@ const PACKED_TOKEN_PART_CODE_UNITS = 64 * 1024;
 const NATIVE_PARSE_READ_BUDGET = 8 * 1024 * 1024;
 
 /** Heap a whole-file native JSON.parse may need: the assembler's 64x container expansion plus byte and text copies. */
-export const nativeJsonParseRequiredBytes = (inputBytes: number): number =>
+export const nativeJsonParseRequiredBytes = (
+  inputBytes: number,
+  snapshot = false,
+): number =>
   // The assembler estimate reserves up to 128 bytes per two-byte container.
   // Allow that 64x expansion plus byte/text copies before native JSON.parse,
   // whose individual container allocations cannot be intercepted.
-  inputBytes * 72 + READ_CHUNK_BYTES;
+  (inputBytes * 72 + READ_CHUNK_BYTES) * (snapshot ? 2 : 1);
 
 /** Snapshot mode also reserves one projection for cooperative sealing bookkeeping. */
 const nativeParseFits = (inputBytes: number, snapshot = false): boolean =>
   inputBytes <= NATIVE_PARSE_READ_BUDGET &&
-  nativeJsonParseRequiredBytes(inputBytes) * (snapshot ? 2 : 1) <=
+  nativeJsonParseRequiredBytes(inputBytes, snapshot) <=
     getHeapStatistics().total_available_size;
 
 /** One selected root member; repeated keys begin again with last-value semantics. */
diff --git a/src/application/environment/environmentBundle.test.ts b/src/application/environment/environmentBundle.test.ts
index c8a12a3493..20ca942502 100644
--- a/src/application/environment/environmentBundle.test.ts
+++ b/src/application/environment/environmentBundle.test.ts
@@ -186,6 +186,32 @@ describe("planEnvironmentBundle", () => {
   });
 });
 
+describe("planEnvironmentBundle portable names", () => {
+  it("refuses device names Windows reserves for files and folders, before planning any file", () => {
+    for (const name of ["con", "prn", "aux", "nul", "com1", "lpt9"]) {
+      const refused = planEnvironmentBundle(environmentServeSource(), {
+        name,
+        packageSource: registryPackageSource(),
+      });
+      if (refused.ok) throw new Error(`Expected ${name} to be refused`);
+      expect(projectAnalysisError(refused.error)).toMatchObject({
+        code: "invalid_request",
+        details: {
+          operation: "environment-export",
+          issues: [{ path: ["name"], reason: "invalid_value" }],
+        },
+      });
+    }
+    for (const name of ["console", "com10", "nul-check"])
+      expect(
+        planEnvironmentBundle(environmentServeSource(), {
+          name,
+          packageSource: registryPackageSource(),
+        }).ok,
+      ).toBe(true);
+  });
+});
+
 describe("planEnvironmentBundle replay check", () => {
   it("keeps the first record's unknown status instead of borrowing another record's", () => {
     const source = environmentServeSource();
diff --git a/src/application/environment/environmentBundle.ts b/src/application/environment/environmentBundle.ts
index 0295d4f6cf..b82227aaf6 100644
--- a/src/application/environment/environmentBundle.ts
+++ b/src/application/environment/environmentBundle.ts
@@ -21,9 +21,10 @@ export const BUNDLE_MCP_PORT = 18765;
 export const BUNDLE_TARBALL_NAME = "rea-agents.tgz";
 
 /** Folder and env id rule: a kebab-case label the agentenv framework accepts as a local id. */
-const BUNDLE_NAME =
-  /^(?!(?:con|prn|aux|nul|com[1-9]|lpt[1-9])$)[a-z0-9]+(?:-[a-z0-9]+)*$/u;
+const BUNDLE_NAME = /^[a-z0-9]+(?:-[a-z0-9]+)*$/u;
 const BUNDLE_NAME_MAX_LENGTH = 64;
+/** Win32 reserves these device names for files and folders, so the env folder can never take one. */
+const WINDOWS_RESERVED_NAME = /^(?:con|prn|aux|nul|com[1-9]|lpt[1-9])$/u;
 
 /** Where the Dockerfile installs the CLI from. */
 export type EnvironmentPackageSource =
@@ -88,6 +89,22 @@ const nameError = (name: string): AnalysisInputError =>
     ],
   );
 
+const reservedNameError = (name: string): AnalysisInputError =>
+  new AnalysisInputError(
+    ENVIRONMENT_EXPORT_OPERATION,
+    {
+      userMessage: `The bundle name ${JSON.stringify(name)} is a device name Windows reserves, so it cannot name the env folder; pass --name with another label.`,
+    },
+    [
+      {
+        path: ["name"],
+        reason: "invalid_value",
+        message:
+          "con, prn, aux, nul, com1-com9 and lpt1-lpt9 are reserved file names on Windows.",
+      },
+    ],
+  );
+
 const installLine = (source: EnvironmentPackageSource): string =>
   source.kind === "registry"
     ? `RUN npm install -g --ignore-scripts --no-fund --no-audit ${source.specifier}`
@@ -277,6 +294,7 @@ export const planEnvironmentBundle = (
   const name = options.name ?? source.manifest.name;
   if (!BUNDLE_NAME.test(name) || name.length > BUNDLE_NAME_MAX_LENGTH)
     return err(nameError(name));
+  if (WINDOWS_RESERVED_NAME.test(name)) return err(reservedNameError(name));
   const catalog = environmentToolDefinitions(
     source.manifest,
     source.evidenceId,
diff --git a/src/application/environment/environmentExport.test.ts b/src/application/environment/environmentExport.test.ts
index deba925f8f..889bea962d 100644
--- a/src/application/environment/environmentExport.test.ts
+++ b/src/application/environment/environmentExport.test.ts
@@ -12,6 +12,7 @@ import {
 import { createTestTempDirectory } from "../../../tests/fixtures/temporaryDirectory.js";
 import { projectAnalysisError } from "../../domain/analysisErrorProjection.js";
 import { PACKAGE_METADATA } from "../../generatedPackageMetadata.js";
+import { nativeJsonParseRequiredBytes } from "../JsonInputFile.js";
 import {
   exportEnvironmentBundle,
   readEnvironmentExportInputs,
@@ -270,3 +271,34 @@ describe("exportEnvironmentBundle file modes", () => {
     },
   );
 });
+
+describe("readEnvironmentExportInputs heap admission", () => {
+  it("reserves headroom for snapshot sealing after the native parse", async () => {
+    const root = await createTestTempDirectory(
+      "rea-environment-export-copies-",
+    );
+    const files = await writeEnvironmentServeFiles(
+      root,
+      environmentServeFixture(),
+    );
+    const { size } = await stat(files.manifestPath);
+    // Room for parsing, but not for the owned snapshot traversal that follows it.
+    vi.mocked(v8.getHeapStatistics).mockReturnValueOnce({
+      ...v8.getHeapStatistics(),
+      total_available_size: nativeJsonParseRequiredBytes(size) * 1.5,
+    });
+    const refused = await readEnvironmentExportInputs(
+      files.manifestPath,
+      files.capturePath,
+    );
+    expect(refused.ok).toBe(false);
+    if (refused.ok) return;
+    expect(refused.error).toMatchObject({
+      _tag: "AnalysisResourceConstraintError",
+      reportedLimits: {
+        input_path: files.manifestPath,
+        required_heap_bytes: nativeJsonParseRequiredBytes(size, true),
+      },
+    });
+  });
+});
diff --git a/src/application/environment/environmentExport.ts b/src/application/environment/environmentExport.ts
index df896a8358..7847f63f9b 100644
--- a/src/application/environment/environmentExport.ts
+++ b/src/application/environment/environmentExport.ts
@@ -178,13 +178,13 @@ const NOT_A_FILE_CODES = new Set([
   "ENAMETOOLONG",
 ]);
 
-/** Refuse, as a resource constraint, a file whose whole read and native parse would not fit live heap headroom. */
+/** Refuse a whole read, native parse and owned snapshot traversal that cannot fit live heap headroom. */
 const headroomRefusal = (
   path: string,
   inputBytes: number,
 ): AnalysisResourceConstraintError | undefined => {
   const heap = getHeapStatistics();
-  const requiredBytes = nativeJsonParseRequiredBytes(inputBytes) * 2;
+  const requiredBytes = nativeJsonParseRequiredBytes(inputBytes, true);
   return requiredBytes <= heap.total_available_size
     ? undefined
     : new AnalysisResourceConstraintError(
diff --git a/src/cli/environmentCommands.ts b/src/cli/environmentCommands.ts
index b8550e8916..aae3ebc14b 100644
--- a/src/cli/environmentCommands.ts
+++ b/src/cli/environmentCommands.ts
@@ -190,6 +190,9 @@ const exportEnvironmentCommand = async (
     input.evidence,
   );
   if (!inputs.ok) return cliError(inputs.error);
+  // Loaded here, as for environment-serve, so registering the command catalog never loads it.
+  const { loadEnvironmentSource } =
+    await import("../application/environment/environmentSource.js");
   const source = loadEnvironmentSource(
     inputs.value.manifest.value,
     inputs.value.evidence.value,