diff --git a/src/application/ClientConfigurationFiles.ts b/src/application/ClientConfigurationFiles.ts
index 5982f53a9..a3ff426e7 100644
--- a/src/application/ClientConfigurationFiles.ts
+++ b/src/application/ClientConfigurationFiles.ts
@@ -1,5 +1,5 @@
 import { err, ok, type Result } from "../domain/result.js";
-import { readFile } from "node:fs/promises";
+import { readRegularFileText } from "./RegularFileRead.js";
 import {
   effectiveClientServer,
   parseClientConfiguration,
@@ -19,7 +19,7 @@ export const readConfigurationText = async (
   path: string,
 ): Promise<Result<string | undefined, ClientConfigurationFileError>> => {
   try {
-    return ok(await readFile(path, "utf8"));
+    return ok(await readRegularFileText(path));
   } catch (cause: unknown) {
     if (cause instanceof Error && "code" in cause && cause.code === "ENOENT")
       return ok(undefined);
diff --git a/src/application/ReferenceSourceImportPolicy.ts b/src/application/ReferenceSourceImportPolicy.ts
index 0cb467d66..e358c3636 100644
--- a/src/application/ReferenceSourceImportPolicy.ts
+++ b/src/application/ReferenceSourceImportPolicy.ts
@@ -1,7 +1,8 @@
-import { readFile, realpath, stat } from "node:fs/promises";
+import { lstat, realpath, stat } from "node:fs/promises";
 import { join, resolve } from "node:path";
 
 import ignore from "ignore";
+import { readRegularFileText } from "./RegularFileRead.js";
 
 import { err, ok, type Result } from "../domain/result.js";
 import {
@@ -47,14 +48,27 @@ const resolveRoot = async (
 const buildIgnored = async (
   root: string,
   excludePaths: readonly string[],
+  signal?: AbortSignal,
 ): Promise<ReturnType<typeof ignore>> => {
   const ignored = ignore();
+  const policyPath = join(root, ".gitignore");
+  let present = true;
   try {
-    ignored.add(await readFile(join(root, ".gitignore"), "utf8"));
+    await lstat(policyPath);
   } catch (cause: unknown) {
-    // Missing or unreadable ignore file does not authorize broader access.
-    void cause;
+    if (
+      !(
+        typeof cause === "object" &&
+        cause !== null &&
+        "code" in cause &&
+        cause.code === "ENOENT"
+      )
+    )
+      throw cause;
+    present = false;
   }
+  signal?.throwIfAborted();
+  if (present) ignored.add(await readRegularFileText(policyPath, { signal }));
   ignored.add([...DEFAULT_REFERENCE_SOURCE_IGNORE_PATTERNS]);
   for (const path of excludePaths) {
     ignored.add(path);
@@ -71,9 +85,22 @@ export const prepareReferenceSourceImport = async (
 > => {
   const root = await resolveRoot(options.root);
   if (!root.ok) return root;
-  return ok({
-    root: root.value,
-    ignored: await buildIgnored(root.value, options.excludePaths ?? []),
-    secrets: ignore().add([...options.policy.secretPatterns]),
-  });
+  try {
+    return ok({
+      root: root.value,
+      ignored: await buildIgnored(
+        root.value,
+        options.excludePaths ?? [],
+        options.signal,
+      ),
+      secrets: ignore().add([...options.policy.secretPatterns]),
+    });
+  } catch (cause: unknown) {
+    return err(
+      failure(
+        options.signal?.aborted === true ? "cancelled" : "io",
+        `Reference source ignore policy could not be read at ${join(root.value, ".gitignore")}: ${cause instanceof Error ? cause.message : String(cause)}`,
+      ),
+    );
+  }
 };
diff --git a/src/application/ReferenceSourceVcsAdapter.ts b/src/application/ReferenceSourceVcsAdapter.ts
index 3ddad25d7..ef136a2ad 100644
--- a/src/application/ReferenceSourceVcsAdapter.ts
+++ b/src/application/ReferenceSourceVcsAdapter.ts
@@ -1,6 +1,7 @@
 import fs from "node:fs";
-import { lstat, readFile } from "node:fs/promises";
+import { lstat } from "node:fs/promises";
 import { join, resolve } from "node:path";
+import { readRegularFile, readRegularFileText } from "./RegularFileRead.js";
 
 export type ReferenceSourceVcsInfo =
   | {
@@ -29,7 +30,7 @@ export const readReferenceSourceVcs = async (
       : { kind: "unknown", head: null, dirty: null };
   }
   try {
-    const head = await resolveSourceHead(root);
+    const head = await resolveSourceHead(root, signal);
     if (isAborted(signal)) return { kind: "unknown", head: null, dirty: null };
     return { kind: "git", head, dirty: null };
   } catch (cause: unknown) {
@@ -39,13 +40,44 @@ export const readReferenceSourceVcs = async (
   }
 };
 
-const resolveSourceHead = async (root: string): Promise<string> => {
+const resolveSourceHead = async (
+  root: string,
+  signal?: AbortSignal,
+): Promise<string> => {
   // isomorphic-git is loaded on first use so CLI and MCP startup skip it.
   const { resolveRef } = await import("isomorphic-git");
+  let failedRead: { readonly cause: unknown } | undefined;
+  const referenceFs = {
+    ...fs,
+    promises: {
+      ...fs.promises,
+      // isomorphic-git treats every read failure as absence. Preserve real
+      // failures so a readable packed ref cannot hide an unreadable loose ref.
+      readFile: async (path: string) => {
+        try {
+          return await readRegularFile(path, { signal });
+        } catch (cause: unknown) {
+          if (errorCode(cause) !== "ENOENT") failedRead ??= { cause };
+          throw cause;
+        }
+      },
+    },
+  };
+  const readRef = async (options: {
+    readonly gitdir?: string;
+    readonly ref: string;
+  }) => {
+    const head = await resolveRef({ fs: referenceFs, dir: root, ...options });
+    signal?.throwIfAborted();
+    if (failedRead !== undefined) throw failedRead.cause;
+    return head;
+  };
   const dotgit = join(root, ".git");
-  if (!(await lstat(dotgit)).isFile())
-    return resolveRef({ fs, dir: root, ref: "HEAD" });
-  const pointer = (await readFile(dotgit, "utf8")).replace(/\r?\n$/u, "");
+  if (!(await lstat(dotgit)).isFile()) return readRef({ ref: "HEAD" });
+  const pointer = (await readRegularFileText(dotgit, { signal })).replace(
+    /\r?\n$/u,
+    "",
+  );
   if (!pointer.startsWith("gitdir: ") || pointer.length === 8)
     throw new Error("Invalid Git directory pointer");
   const gitdir = resolve(root, pointer.slice(8));
@@ -53,25 +85,23 @@ const resolveSourceHead = async (root: string): Promise<string> => {
   try {
     commonDirectory = resolve(
       gitdir,
-      (await readFile(join(gitdir, "commondir"), "utf8")).replace(
-        /\r?\n$/u,
-        "",
-      ),
+      (
+        await readRegularFileText(join(gitdir, "commondir"), { signal })
+      ).replace(/\r?\n$/u, ""),
     );
   } catch (cause: unknown) {
     if (errorCode(cause) !== "ENOENT") throw cause;
-    return resolveRef({ fs, dir: root, gitdir, ref: "HEAD" });
+    return readRef({ gitdir, ref: "HEAD" });
   }
-  const head = (await readFile(join(gitdir, "HEAD"), "utf8")).trim();
-  if (!head.startsWith("ref: "))
-    return resolveRef({ fs, dir: root, gitdir, ref: "HEAD" });
+  const head = (
+    await readRegularFileText(join(gitdir, "HEAD"), { signal })
+  ).trim();
+  if (!head.startsWith("ref: ")) return readRef({ gitdir, ref: "HEAD" });
   const ref = head.slice(5);
   const privateRef = ["refs/bisect/", "refs/rewritten/", "refs/worktree/"].some(
     (prefix) => ref.startsWith(prefix),
   );
-  return resolveRef({
-    fs,
-    dir: root,
+  return readRef({
     gitdir: privateRef ? gitdir : commonDirectory,
     ref,
   });
diff --git a/src/application/SetupClientConfiguration.ts b/src/application/SetupClientConfiguration.ts
index 5cbf95206..4ae8a5ff7 100644
--- a/src/application/SetupClientConfiguration.ts
+++ b/src/application/SetupClientConfiguration.ts
@@ -14,7 +14,7 @@ import {
   type ClientRegistrationDialect,
 } from "./ClientConfigurationDocument.js";
 import { constants as fsConstants } from "node:fs";
-import { copyFile, mkdir, readFile, rm, writeFile } from "node:fs/promises";
+import { copyFile, mkdir, rm, writeFile } from "node:fs/promises";
 import { dirname } from "node:path";
 import writeFileAtomic from "write-file-atomic";
 
@@ -22,6 +22,7 @@ import { PRODUCT_IDENTITY } from "../identity.js";
 import { npxRegistrationCommand } from "./ClientRegistrationIdentity.js";
 import { MCP_STARTUP_POLICY } from "../mcpStartupPolicy.js";
 import { resolveClientConfigTransactionPath } from "./ClientConfigPath.js";
+import { readRegularFileText } from "./RegularFileRead.js";
 import type {
   ClientConfigurationInspection,
   ClientConfigurationResult,
@@ -64,7 +65,7 @@ const configureClientDocument = async (
     return { status: "failed", reason: "path" };
   let original: string | undefined;
   try {
-    original = await readFile(transactionPath, "utf8");
+    original = await readRegularFileText(transactionPath);
   } catch (cause: unknown) {
     if (!isMissing(cause)) return { status: "failed", reason: "readback" };
   }
@@ -149,7 +150,7 @@ const configureClientDocument = async (
   }
   try {
     const readback = parseClientConfiguration(
-      await readFile(transactionPath, "utf8"),
+      await readRegularFileText(transactionPath),
       format,
     );
     if (!registrationCurrent(readback, desired)) {
@@ -178,7 +179,7 @@ export const clientConfigurationAligned = async (
   try {
     const files = await readClientConfigurationFiles(client);
     if (!files.ok) return false;
-    const original = await readFile(client.configPath, "utf8");
+    const original = await readRegularFileText(client.configPath);
     const parsed = parseClientConfiguration(original, client.format);
     const policy = await readClientPolicyBlock(
       client,
@@ -246,7 +247,7 @@ export const inspectClientConfiguration = async (
     };
   let original: string;
   try {
-    original = await readFile(transactionPath, "utf8");
+    original = await readRegularFileText(transactionPath);
   } catch (cause: unknown) {
     if (isMissing(cause)) return { status: "create" };
     return {
diff --git a/src/application/SetupSkill.ts b/src/application/SetupSkill.ts
index b0770c31a..25228d14b 100644
--- a/src/application/SetupSkill.ts
+++ b/src/application/SetupSkill.ts
@@ -4,10 +4,8 @@ import { dirname, join } from "node:path";
 import writeFileAtomic from "write-file-atomic";
 
 import { PRODUCT_IDENTITY } from "../identity.js";
-import {
-  NonRegularFileReadError,
-  openRegularFile,
-} from "../filesystem/RegularFile.js";
+import { NonRegularFileReadError } from "../filesystem/RegularFile.js";
+import { readRegularFileText } from "./RegularFileRead.js";
 import { clientSkillDirectories } from "./SupportedClients.js";
 
 export const MANAGED_SKILL_FILES = [
@@ -23,14 +21,8 @@ export const isManagedSkillManifest = (content: string): boolean =>
   content.startsWith(`---\nname: ${PRODUCT_IDENTITY.skillName}\n`) ||
   content.startsWith(`---\r\nname: ${PRODUCT_IDENTITY.skillName}\r\n`);
 
-export const readSkillFile = async (path: string): Promise<string> => {
-  const handle = await openRegularFile(path, { symlinks: "reject" });
-  try {
-    return await handle.readFile("utf8");
-  } finally {
-    await handle.close();
-  }
-};
+export const readSkillFile = (path: string): Promise<string> =>
+  readRegularFileText(path, { symlinks: "reject" });
 
 interface CanonicalSkillFile {
   readonly content: string;
@@ -199,7 +191,7 @@ export const installCanonicalSkill = async (
     for (const { destination, content } of changed)
       await writeText(destination, content);
     for (const { destination, content } of changed)
-      if ((await readFile(destination, "utf8")) !== content)
+      if ((await readSkillFile(destination)) !== content)
         throw new Error(`skill readback mismatch: ${destination}`);
     return "installed";
   } catch (cause: unknown) {
@@ -231,7 +223,7 @@ export const readInstalledSkillIdentity = async (
   let content: string | undefined;
   for (const destination of destinations) {
     try {
-      content = await readFile(join(destination.path, "SKILL.md"), "utf8");
+      content = await readSkillFile(join(destination.path, "SKILL.md"));
       break;
     } catch {
       // Another selected copy may provide metadata; canonical validation below
diff --git a/src/application/Uninstall.ts b/src/application/Uninstall.ts
index 73986c3c3..6310ce99b 100644
--- a/src/application/Uninstall.ts
+++ b/src/application/Uninstall.ts
@@ -6,7 +6,7 @@ import {
   withClientServers,
   type ClientConfigurationDocument,
 } from "./ClientConfigurationDocument.js";
-import { copyFile, lstat, readFile, realpath, rm } from "node:fs/promises";
+import { copyFile, lstat, realpath, rm } from "node:fs/promises";
 import { constants as fsConstants } from "node:fs";
 import { homeDirectoryFromEnvironment } from "../config/homeDirectory.js";
 import { join } from "node:path";
@@ -23,6 +23,7 @@ import {
 } from "./SetupSkill.js";
 import { isOwnedClientRegistrationCommand } from "./ClientRegistrationIdentity.js";
 import { resolveClientConfigTransactionPath } from "./ClientConfigPath.js";
+import { readRegularFileText } from "./RegularFileRead.js";
 import {
   manualRegistrationRemediation,
   supportedClients,
@@ -49,7 +50,7 @@ export interface UninstallFileSystem {
 }
 
 const systemFileSystem: UninstallFileSystem = {
-  readText: (path) => readFile(path, "utf8"),
+  readText: (path) => readRegularFileText(path),
   readRegularText: readSkillFile,
   copy: (source, destination) =>
     copyFile(source, destination, fsConstants.COPYFILE_EXCL),
diff --git a/src/application/UpdateMaintenance.ts b/src/application/UpdateMaintenance.ts
index 40d66bcbc..2a5a286d5 100644
--- a/src/application/UpdateMaintenance.ts
+++ b/src/application/UpdateMaintenance.ts
@@ -1,4 +1,3 @@
-import { readFile } from "node:fs/promises";
 import { z } from "zod";
 
 import { PRODUCT_IDENTITY } from "../identity.js";
@@ -14,6 +13,7 @@ import { supportedClients } from "./SupportedClients.js";
 import { existingSkillDestinations } from "./SetupSkill.js";
 import type { SetupAction } from "./SetupTypes.js";
 import type { Result } from "../domain/result.js";
+import { readRegularFileText } from "./RegularFileRead.js";
 
 /** Existing REA integrations selected for maintenance, without discovering new targets. */
 export interface MaintenanceScope {
@@ -73,7 +73,7 @@ export const existingMaintenanceScope = async (
     const client = supported.find(({ name }) => name === registration.client);
     if (client === undefined) continue;
     const parsed = parseClientConfiguration(
-      await readFile(client.configPath, "utf8"),
+      await readRegularFileText(client.configPath),
       client.format,
     );
     const enabled = z
@@ -130,7 +130,9 @@ export const planIntegrationMaintenance = async (
       };
     if (plan.data.plannedActions.length === 0)
       return { status: "current", plannedActions: [] };
-    const allowedIds = new Set(scope.clients.map((client) => `configure_client:${client}`));
+    const allowedIds = new Set(
+      scope.clients.map((client) => `configure_client:${client}`),
+    );
     const skillTargets = new Set(skillDestinations.map(({ path }) => path));
     if (
       plan.data.plannedActions.some((action) =>