diff --git a/.changeset/gcm-auth-tag-length.md b/.changeset/gcm-auth-tag-length.md
new file mode 100644
index 0000000..53186fc
--- /dev/null
+++ b/.changeset/gcm-auth-tag-length.md
@@ -0,0 +1,5 @@
+---
+"@codacy/codacy-cloud-cli": patch
+---
+
+Stored credentials now require the full 16-byte AES-GCM authentication tag. Previously a truncated tag (as short as 4 bytes) still verified, which weakened the integrity check on `~/.codacy/credentials`; existing credential files keep working because the CLI has always written full-length tags. Also tidies a handful of lint findings (unused imports, `??` over `||` for nullish defaults, typed `catch` parameters) and adds a `.codacy.yaml` so Codacy skips test files for ESLint and generated Markdown for markdownlint.
diff --git a/.codacy.yaml b/.codacy.yaml
new file mode 100644
index 0000000..06ea0e7
--- /dev/null
+++ b/.codacy.yaml
@@ -0,0 +1,17 @@
+---
+exclude_paths:
+  # Already ignored in the Codacy UI; repeated here so the file and the UI agree
+  - "src/commands/issues.ts"
+engines:
+  eslint-9:
+    exclude_paths:
+      # Mock-heavy tests: unbound-method on expect(svc.method), `as any`, no-unsafe-*
+      - "**/*.test.ts"
+      - "src/test-support.ts"
+      # changesets helper (.cjs) — ESLint has no Node globals configured for it
+      - ".changeset/**"
+  markdownlint:
+    exclude_paths:
+      - "CHANGELOG.md"
+      - "CODE_OF_CONDUCT.md"
+      - "SPECS/commands/tools-and-patterns.md"
diff --git a/.codacy/codacy.yaml b/.codacy/codacy.yaml
deleted file mode 100644
index 6a8dadd..0000000
--- a/.codacy/codacy.yaml
+++ /dev/null
@@ -1,8 +0,0 @@
-runtimes:
-    - node@22.2.0
-    - python@3.11.11
-tools:
-    - eslint@8.57.0
-    - lizard@1.17.19
-    - semgrep@1.78.0
-    - trivy@0.59.1
diff --git a/AGENTS.md b/AGENTS.md
index 4d8dfd3..293303f 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -249,6 +249,6 @@ When completing work, agents **must** update relevant documentation:
 
 ## Useful Context
 
-- Codacy API docs: https://api.codacy.com/api/api-docs
+- Codacy API docs: <https://api.codacy.com/api/api-docs>
 - The CLI targets Codacy Cloud (app.codacy.com), not self-hosted instances
 - Provider shortcodes used in commands: `gh` (GitHub), `gl` (GitLab), `bb` (Bitbucket)
diff --git a/src/commands/finding.ts b/src/commands/finding.ts
index 058c7e0..127ade6 100644
--- a/src/commands/finding.ts
+++ b/src/commands/finding.ts
@@ -17,7 +17,6 @@ import {
 } from "../utils/formatting";
 import { sanitizeText } from "../utils/sanitize";
 import { SecurityService } from "../api/client/services/SecurityService";
-import { IgnoreSRMItemBody } from "../api/client/models/IgnoreSRMItemBody";
 import { AnalysisService } from "../api/client/services/AnalysisService";
 import { ToolsService } from "../api/client/services/ToolsService";
 import { FileService } from "../api/client/services/FileService";
diff --git a/src/commands/findings.ts b/src/commands/findings.ts
index 1a1d4be..b1b6192 100644
--- a/src/commands/findings.ts
+++ b/src/commands/findings.ts
@@ -236,7 +236,7 @@ export function parseImageFilter(
     const refTag = name.slice(colon + 1);
     name = name.slice(0, colon);
     if (!name || !refTag) {
-      throw new Error(`--image expects name or name:tag (got "${image!.trim()}").`);
+      throw new Error(`--image expects name or name:tag (got "${image?.trim()}").`);
     }
     if (tag && tag !== refTag) {
       throw new Error(
diff --git a/src/commands/issue.ts b/src/commands/issue.ts
index 1f2dc11..c8549b3 100644
--- a/src/commands/issue.ts
+++ b/src/commands/issue.ts
@@ -97,7 +97,7 @@ Examples:
             encodeURIComponent(issue.filePath),
             startLine,
             endLine,
-          ).catch((e) => {
+          ).catch((e: unknown) => {
             console.error(ansis.red(`File path: ${sanitizeText(issue.filePath)}`));
             console.error(ansis.red(`Error fetching file content: ${e}`));
             return null;
diff --git a/src/commands/login.ts b/src/commands/login.ts
index 912aa09..b176396 100644
--- a/src/commands/login.ts
+++ b/src/commands/login.ts
@@ -17,7 +17,7 @@ import {
 /** Reads the account token from `--token`, or prompts for it interactively. */
 const acquireToken = async (tokenOption?: string): Promise<string> => {
   if (tokenOption) {
-    const token = String(tokenOption).trim();
+    const token = tokenOption.trim();
     if (!token) throw new Error("Token cannot be empty.");
     return token;
   }
diff --git a/src/commands/pull-request.ts b/src/commands/pull-request.ts
index ce77589..c13937e 100644
--- a/src/commands/pull-request.ts
+++ b/src/commands/pull-request.ts
@@ -18,7 +18,6 @@ import {
   truncate,
   buildGateStatus,
   formatStandards,
-  colorByGate,
   colorSeverity,
   formatDelta,
   formatPrCoverage,
@@ -207,8 +206,8 @@ function printAbout(
 function buildGateHints(pr: PullRequestWithAnalysis): Record<string, string> {
   const hints: Record<string, string> = {};
   const reasons: AnalysisResultReason[] = [
-    ...(pr.quality?.resultReasons || []),
-    ...(pr.coverage?.resultReasons || []),
+    ...(pr.quality?.resultReasons ?? []),
+    ...(pr.coverage?.resultReasons ?? []),
   ];
   for (const r of reasons) {
     const key = gateKeyFromReason(r.gate);
@@ -325,7 +324,7 @@ function printFilesList(files: FileDeltaAnalysis[]): void {
           q.deltaFixedIssues > 0 ||
           q.deltaComplexity ||
           q.deltaClonesCount)) ||
-      (c && c.deltaCoverage)
+      (c?.deltaCoverage)
     );
   });
 
@@ -573,7 +572,7 @@ function printAnnotatedDiff(
     if (!issuesByFile.has(fp)) issuesByFile.set(fp, new Map());
     const m = issuesByFile.get(fp)!;
     if (!m.has(ln)) m.set(ln, []);
-    m.get(ln)!.push(tagged);
+    m.get(ln)?.push(tagged);
   }
 
   const { files } = parseDiff(diffText, true);
@@ -1267,7 +1266,7 @@ Examples:
             pullRequest: prData,
             newIssues: newIssues.data,
             potentialIssues: potentialIssues.data,
-            files: filesData.data || [],
+            files: filesData.data ?? [],
           }, [
             // About
             "pullRequest.pullRequest.repository",
@@ -1325,7 +1324,7 @@ Examples:
         printDiffCoverageSummary(fileCoverageList);
 
         // Files
-        printFilesList(filesData.data || []);
+        printFilesList(filesData.data ?? []);
         printPaginationWarning(
           filesData.pagination,
           "Not all files are shown.",
diff --git a/src/commands/repository.ts b/src/commands/repository.ts
index 000e93d..eeb054a 100644
--- a/src/commands/repository.ts
+++ b/src/commands/repository.ts
@@ -25,7 +25,6 @@ import {
   truncate,
   buildGateStatus,
   formatStandards,
-  colorByGate,
   formatDelta,
   formatPrCoverage,
   formatRepoCoverageDetail,
@@ -540,7 +539,7 @@ Examples:
             organization,
             repository,
           ),
-          fetchIfAccountToken(auth, noPullRequests(), () =>
+          fetchIfAccountToken(auth, noPullRequests(), async () =>
             AnalysisService.listRepositoryPullRequests(
               provider,
               organization,
diff --git a/src/utils/auth.ts b/src/utils/auth.ts
index 1182bb6..fc551c0 100644
--- a/src/utils/auth.ts
+++ b/src/utils/auth.ts
@@ -236,7 +236,7 @@ export function resolveAccountAuth(command: Command, because: string): AccountAu
  * hang off a non-whitelisted endpoint — see the pull request table in
  * `commands/repository.ts`.
  */
-export function fetchIfAccountToken<T, F>(
+export async function fetchIfAccountToken<T, F>(
   auth: RemoteAuth,
   fallback: F,
   fetch: () => Promise<T>,
diff --git a/src/utils/credentials.test.ts b/src/utils/credentials.test.ts
index b14515e..759baf0 100644
--- a/src/utils/credentials.test.ts
+++ b/src/utils/credentials.test.ts
@@ -54,6 +54,14 @@ describe("credentials", () => {
       expect(parsed).toHaveProperty("encrypted");
     });
 
+    it("should write a full 16-byte auth tag that decryption accepts", () => {
+      const encrypted = encryptToken("test-token");
+      const parsed = JSON.parse(encrypted);
+      // decryptToken rejects anything shorter, so the writer must emit 16 bytes
+      expect(Buffer.from(parsed.authTag, "hex")).toHaveLength(16);
+      expect(decryptToken(encrypted)).toBe("test-token");
+    });
+
     it("should produce different ciphertexts for the same token (random salt/iv)", () => {
       const token = "same-token";
       const a = encryptToken(token);
@@ -71,6 +79,15 @@ describe("credentials", () => {
       expect(() => decryptToken(JSON.stringify(parsed))).toThrow();
     });
 
+    it("should reject a truncated auth tag", () => {
+      // A prefix of a valid GCM tag still verifies unless the tag length is
+      // pinned, so this would decrypt successfully without authTagLength.
+      const encrypted = encryptToken("my-secret");
+      const parsed = JSON.parse(encrypted);
+      parsed.authTag = parsed.authTag.slice(0, 8);
+      expect(() => decryptToken(JSON.stringify(parsed))).toThrow();
+    });
+
     it("should throw on invalid JSON", () => {
       expect(() => decryptToken("not-json")).toThrow();
     });
diff --git a/src/utils/credentials.ts b/src/utils/credentials.ts
index 14aae0b..7a3e881 100644
--- a/src/utils/credentials.ts
+++ b/src/utils/credentials.ts
@@ -10,6 +10,10 @@ const ALGORITHM = "aes-256-gcm";
 const KEY_LENGTH = 32;
 const IV_LENGTH = 16;
 const SALT_LENGTH = 32;
+// GCM tags can legally be truncated (down to 4 bytes), and a truncated prefix of
+// a valid tag still verifies unless the expected length is pinned. We always
+// write the full 16-byte tag, so require exactly that on read.
+const AUTH_TAG_LENGTH = 16;
 const PBKDF2_ITERATIONS = 100_000;
 const PBKDF2_DIGEST = "sha512";
 
@@ -40,7 +44,9 @@ export function encryptToken(token: string): string {
   const iv = crypto.randomBytes(IV_LENGTH);
   const key = deriveKey(getMachineKey(), salt);
 
-  const cipher = crypto.createCipheriv(ALGORITHM, key, iv);
+  const cipher = crypto.createCipheriv(ALGORITHM, key, iv, {
+    authTagLength: AUTH_TAG_LENGTH,
+  });
   const encrypted = Buffer.concat([
     cipher.update(token, "utf8"),
     cipher.final(),
@@ -66,7 +72,13 @@ export function decryptToken(payloadJson: string): string {
   const encrypted = Buffer.from(payload.encrypted, "hex");
   const key = deriveKey(getMachineKey(), salt);
 
-  const decipher = crypto.createDecipheriv(ALGORITHM, key, iv);
+  if (authTag.length !== AUTH_TAG_LENGTH) {
+    throw new Error("Invalid authentication tag length");
+  }
+
+  const decipher = crypto.createDecipheriv(ALGORITHM, key, iv, {
+    authTagLength: AUTH_TAG_LENGTH,
+  });
   decipher.setAuthTag(authTag);
 
   const decrypted = Buffer.concat([
@@ -123,7 +135,7 @@ export function deleteCredentials(): boolean {
   }
 }
 
-export function promptForToken(prompt: string): Promise<string> {
+export async function promptForToken(prompt: string): Promise<string> {
   return new Promise((resolve, reject) => {
     if (!process.stdin.isTTY) {
       reject(new Error("Interactive input required. Use --token <value> instead."));
@@ -138,7 +150,7 @@ export function promptForToken(prompt: string): Promise<string> {
     let token = "";
 
     const onData = (char: string) => {
-      const chunk = char.toString();
+      const chunk = char;
 
       for (const c of chunk) {
         if (c === "\n" || c === "\r") {
diff --git a/src/utils/diff.ts b/src/utils/diff.ts
index fe6c087..d8104f6 100644
--- a/src/utils/diff.ts
+++ b/src/utils/diff.ts
@@ -1,4 +1,4 @@
-import gitDiffParser, { File } from "gitdiff-parser";
+import gitDiffParser from "gitdiff-parser";
 import { sortBy } from "lodash";
 
 // TODO: remove this when the API has the correct diff for commits coming from Git
diff --git a/src/utils/formatting.ts b/src/utils/formatting.ts
index f8533a9..477412a 100644
--- a/src/utils/formatting.ts
+++ b/src/utils/formatting.ts
@@ -550,7 +550,7 @@ export function formatRepoCoverageCell(
 function hasCoverageValue(coverage: Coverage | undefined): boolean {
   return (
     coverage?.coveragePercentage !== undefined &&
-    coverage?.coveragePercentage !== null
+    coverage.coveragePercentage !== null
   );
 }
 
@@ -703,8 +703,8 @@ export function formatDelta(
 export function buildGateStatus(pr: PullRequestWithAnalysis): GateStatusMap {
   const status: GateStatusMap = {};
   const reasons: AnalysisResultReason[] = [
-    ...(pr.quality?.resultReasons || []),
-    ...(pr.coverage?.resultReasons || []),
+    ...(pr.quality?.resultReasons ?? []),
+    ...(pr.coverage?.resultReasons ?? []),
   ];
   for (const r of reasons) {
     const gate = r.gate.toLowerCase();
@@ -1249,9 +1249,7 @@ export async function resolveToolUuids(
       continue;
     }
 
-    if (!allTools) {
-      allTools = await fetchTools();
-    }
+    allTools ??= await fetchTools();
 
     const lower = input.toLowerCase();
 
@@ -1274,7 +1272,7 @@ export async function resolveToolUuids(
       return (
         t.name.toLowerCase().includes(lower) ||
         t.shortName.toLowerCase().includes(lower) ||
-        (t.prefix && t.prefix.toLowerCase().includes(lower))
+        (t.prefix?.toLowerCase().includes(lower))
       );
     });
 
diff --git a/src/utils/git-remote.ts b/src/utils/git-remote.ts
index 0db802a..35b81c6 100644
--- a/src/utils/git-remote.ts
+++ b/src/utils/git-remote.ts
@@ -21,7 +21,7 @@ function stripUserinfo(host: string): string {
 }
 
 export function parseGitRemoteUrl(url: string): RepoContext | null {
-  const match = url.match(SSH_REGEX) || url.match(HTTPS_REGEX);
+  const match = (SSH_REGEX.exec(url)) ?? (HTTPS_REGEX.exec(url));
   if (!match) return null;
 
   const [, rawHost, org, repo] = match;
diff --git a/src/utils/import-config.ts b/src/utils/import-config.ts
index 02daa24..5ba7655 100644
--- a/src/utils/import-config.ts
+++ b/src/utils/import-config.ts
@@ -98,7 +98,7 @@ export function resolveToolId(
 
   // Match by prefix (strip trailing _ before comparing)
   const byPrefix = allTools.find(
-    (t) => t.prefix && t.prefix.replace(/_$/, "").toLowerCase() === id,
+    (t) => t.prefix?.replace(/_$/, "").toLowerCase() === id,
   );
   if (byPrefix) return byPrefix;
 
@@ -125,7 +125,7 @@ export async function getLocalSupportedToolIds(): Promise<string[] | null> {
     const info = JSON.parse(stdout);
     if (!info.tools || !Array.isArray(info.tools)) return null;
     return info.tools
-      .filter((t: any) => t && t.supported && typeof t.id === "string")
+      .filter((t: any) => t?.supported && typeof t.id === "string")
       .map((t: any) => t.id as string);
   } catch {
     return null;
@@ -193,12 +193,12 @@ export function buildImportPreview(
 
   // Tools in the config that need enabling (currently disabled or not present)
   const toolsToEnable = resolved.filter(
-    (r) => !r.repoTool || !r.repoTool.settings.isEnabled,
+    (r) => !r.repoTool?.settings.isEnabled,
   );
 
   // Tools in the config that are already enabled (need reconfiguration)
   const toolsToReconfigure = resolved.filter(
-    (r) => r.repoTool && r.repoTool.settings.isEnabled,
+    (r) => r.repoTool?.settings.isEnabled,
   );
 
   const { toolsToDisable, cloudOnlyTools } = splitEnabledNotInConfig(
diff --git a/src/utils/prompt.ts b/src/utils/prompt.ts
index 9623f69..ddf4e5a 100644
--- a/src/utils/prompt.ts
+++ b/src/utils/prompt.ts
@@ -17,7 +17,7 @@ import * as readline from "readline";
  * to answer must abort rather than delete by accident. `-y` is how a caller
  * says yes ahead of time.
  */
-export function confirmAction(message: string): Promise<boolean> {
+export async function confirmAction(message: string): Promise<boolean> {
   return new Promise((resolve) => {
     if (!process.stdin.isTTY) {
       resolve(false);
diff --git a/src/utils/reanalyze-wait.ts b/src/utils/reanalyze-wait.ts
index 3ad4ae5..cd7a3a1 100644
--- a/src/utils/reanalyze-wait.ts
+++ b/src/utils/reanalyze-wait.ts
@@ -33,8 +33,8 @@ export const PATTERN_LIMIT = 20;
  * resolver (`vi.spyOn(timers, "sleep").mockResolvedValue()`).
  */
 export const timers = {
-  sleep(ms: number): Promise<void> {
-    return new Promise((resolve) => setTimeout(resolve, ms));
+  async sleep(ms: number): Promise<void> {
+    return new Promise((resolve) => void setTimeout(resolve, ms));
   },
 };
 
diff --git a/src/utils/repo-tree.ts b/src/utils/repo-tree.ts
index d0011ca..b162355 100644
--- a/src/utils/repo-tree.ts
+++ b/src/utils/repo-tree.ts
@@ -74,7 +74,7 @@ export async function mapWithConcurrency<T>(
     }
   };
   const size = Math.min(limit, items.length);
-  await Promise.all(Array.from({ length: size }, () => worker()));
+  await Promise.all(Array.from({ length: size }, async () => worker()));
 }
 
 /**