fix(javascript): keep selected-input filesystem failures typed

A selected directory that is readable but not searchable passed the R_OK
selection check, then every entry lstat failed and the result became a
generic artifact I/O failure. The selection owner now checks search
permission for directories and reads the selection metadata inside its
classifier, so EACCES/EPERM from realpath, lstat or access is a host
access denial with the selected path and system code.

Host filesystem failures that no narrower owner classifies no longer
drop their facts: EMFILE/ENFILE become a retryable capacity constraint,
and other errno failures keep artifact I/O with the host message and
system_code, syscall and path diagnostics.

Fixes #6116
Fixes #5991

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/application/javascript/JavaScriptApplicationService.ts

@@ -7,7 +7,10 @@ import {
   type JavaScriptApplicationAnalysisResult,
   parseOwnedJavaScriptApplicationAnalysisSteps,
 } from "../../domain/javascript/javascriptApplicationAnalysis.js";
-import { AnalysisOutputError } from "../../domain/analysisErrorCore.js";
+import {
+  AnalysisOutputError,
+  AnalysisResourceConstraintError,
+} from "../../domain/analysisErrorCore.js";
 import { ArtifactOperationError } from "../../domain/artifactOperationError.js";
 import { AnalysisError } from "../../domain/analysisErrorBase.js";
 import type { Evidence } from "../../domain/evidence.js";
@@ -149,13 +152,8 @@ export const analyzeJavaScriptApplicationValidated = async (
           cause,
         }),
       );
-    if (
-      cause instanceof Error &&
-      "code" in cause &&
-      typeof cause.code === "string" &&
-      FILESYSTEM_ERROR_CODES.has(cause.code)
-    )
-      return err(new ArtifactOperationError(OPERATION, "io"));
+    const filesystemFailure = hostFilesystemFailure(cause);
+    if (filesystemFailure !== undefined) return err(filesystemFailure);
     return err(
       new ProviderAdapterError(JAVASCRIPT_APPLICATION_PROVIDER.id, OPERATION, {
         cause,
@@ -208,6 +206,43 @@ const describeResultSchemaFailure = (cause: z.ZodError): string => {
 const escapePointerPart = (part: string): string =>
   part.replaceAll("~", "~0").replaceAll("/", "~1");
 
+/**
+ * Project a host filesystem failure that no narrower owner classified. Selected
+ * input denial is classified at selection; this failure may concern any path,
+ * including private workspace files, so it keeps the host's own facts rather
+ * than claiming a selected-read denial.
+ */
+const hostFilesystemFailure = (cause: unknown): AnalysisError | undefined => {
+  if (!(cause instanceof Error)) return undefined;
+  const code: unknown = Reflect.get(cause, "code");
+  if (typeof code !== "string" || !FILESYSTEM_ERROR_CODES.has(code))
+    return undefined;
+  const syscall: unknown = Reflect.get(cause, "syscall");
+  const path: unknown = Reflect.get(cause, "path");
+  const facts = {
+    system_code: code,
+    ...(typeof syscall === "string" ? { syscall } : {}),
+    ...(typeof path === "string" ? { path } : {}),
+  };
+  if (code === "EMFILE" || code === "ENFILE")
+    return new AnalysisResourceConstraintError(
+      OPERATION,
+      "capacity",
+      `Host file-descriptor limit reached (${code})${typeof path === "string" ? ` while accessing ${path}` : ""}`,
+      facts,
+      {
+        cause,
+        retryable: true,
+        remediationAction:
+          "Close unused files or raise the open-file limit for the process or host running REA, then retry.",
+      },
+    );
+  return new ArtifactOperationError(OPERATION, "io", undefined, cause.message, {
+    cause,
+    diagnostics: facts,
+  });
+};
+
 const FILESYSTEM_ERROR_CODES = new Set([
   "ENOENT",
   "EACCES",

src/application/javascript/JavaScriptArtifactReconstruction.ts

@@ -1,4 +1,4 @@
-import { constants } from "node:fs";
+import { constants, type Stats } from "node:fs";
 import { access, lstat, realpath } from "node:fs/promises";
 import { setImmediate } from "node:timers/promises";
 
@@ -91,8 +91,8 @@ export const reconstructJavaScriptArtifact = async (
     };
     const input = javascriptArtifactReconstructionInputSchema.parse(rawInput);
     abortIfNeeded(signal);
-    const path = await resolveSelectedInput(input.input_path);
-    const format = await resolveFormat(path, input);
+    const { path, metadata } = await resolveSelectedInput(input.input_path);
+    const format = selectedFormat(path, metadata, input);
     const snapshot = await scanCanonicalArtifactInventoryInScope(path, {
       resourceScope: scope,
       signal,
@@ -346,13 +346,21 @@ const OPERATION = "analyze_javascript_application";
 /**
  * Resolve the caller-selected input. A missing, looping, overlong, or
  * unreadable selection is a caller or host-resolution failure, not a damaged
- * artifact.
+ * artifact. A selected directory must also be searchable: without search
+ * permission its entries can be listed but not inspected, so no entry is
+ * readable. Other host failures propagate with their errno facts intact.
  */
-const resolveSelectedInput = async (inputPath: string): Promise<string> => {
+const resolveSelectedInput = async (
+  inputPath: string,
+): Promise<{ readonly path: string; readonly metadata: Stats }> => {
   try {
     const path = await realpath(inputPath);
-    await access(path, constants.R_OK);
-    return path;
+    const metadata = await lstat(path);
+    await access(
+      path,
+      metadata.isDirectory() ? constants.R_OK | constants.X_OK : constants.R_OK,
+    );
+    return { path, metadata };
   } catch (cause: unknown) {
     const code =
       cause instanceof Error && "code" in cause ? String(cause.code) : "";
@@ -389,11 +397,11 @@ const selectedInputResolutionMessage = (
     : `Selected input path could not be resolved because symbolic-link traversal looped or exceeded the host limit (ELOOP): ${inputPath}`;
 
 /** The selected input's kind, checked against the caller's requested format. */
-const resolveFormat = async (
+const selectedFormat = (
   path: string,
+  metadata: Stats,
   input: JavaScriptArtifactReconstructionInput,
-): Promise<"asar" | "directory"> => {
-  const metadata = await lstat(path);
+): "asar" | "directory" => {
   const observed = metadata.isDirectory()
     ? "directory"
     : metadata.isFile() && path.toLowerCase().endsWith(".asar")