fix: harden kata boundaries and validation

.github/workflows/maven.yml

@@ -10,6 +10,26 @@ permissions:
   contents: read
 
 jobs:
+  offline-gate:
+    name: Offline gate (Windows, JDK 21)
+    runs-on: windows-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+        with:
+          persist-credentials: false
+      - name: Set up JDK
+        uses: actions/setup-java@1bcf9fb12cf4aa7d266a90ae39939e61372fe520 # v5.4.0
+        with:
+          distribution: temurin
+          java-version: 21
+          cache: maven
+      - name: Prime the exact Maven test runtime
+        run: mvn -B -ntp "-Dtest=quality.SmokeMethodTestHarnessTest" test --file pom.xml
+      - name: Run the strict offline test gate
+        shell: pwsh
+        run: .\scripts\run-offline-gate.ps1 -Goal test -StrictDependencies
+
   category-tests:
     name: Test (${{ matrix.category }})
     runs-on: ubuntu-latest

ARCHITECTURE.md

@@ -9,6 +9,7 @@
   - `IntegrationSuite` – stateful transaction validation behavior.
   - `PropertySuite` – jqwik property/invariant tests.
 - `.github` contains CI, templates, and dependency automation.
+- `scripts/run-offline-gate.ps1` provides a network-free local Maven quality gate.
 
 ## Design principles used in this repo
 
@@ -33,5 +34,5 @@
 ## Future quality directions
 
 - Increase property coverage into additional stable, pure utilities where invariant checks are natural.
-- Add explicit domain-level integration tests for edge-case transaction flows (duplicates / ordering / insufficient balance).
+- Expand domain-level integration coverage when new transaction rules are introduced.
 - Keep production methods with concise intent comments for non-obvious logic.

CHANGELOG.md

@@ -1,5 +1,16 @@
 # Changelog
 
+## Unreleased
+
+- Corrected boundary, overflow, validation, determinism and complexity defects across kata utilities.
+- Hardened transaction validation and made returned status collections immutable.
+- Replaced unbounded iteration in encryption and range-counting helpers with logarithmic algorithms.
+- Made the generated smoke harness fail when every executable API path fails.
+- Added regression coverage for scheduler extremes, queueing, Fibonacci, trailing zeros and other edge cases.
+- Added a PowerShell offline quality gate with strict dependency-cache mode and a documented cached-JUnit fallback.
+- Added a Windows CI job that primes dependencies and then exercises the strict offline gate.
+- Expanded the verified test baseline to 594 tests.
+
 ## 1.1 - public quality hardening (2026-06-09)
 
 - Added CI, static analysis, and dependency management updates for repository quality.

README.en.md

@@ -34,6 +34,7 @@ This repository is a portfolio-grade Java kata workspace focused on deterministi
 ## CI and Quality Signals
 
 - `.github/workflows/maven.yml` runs category jobs on JDK 21 and full `mvn verify` on JDK 17 and 21.
+- The same workflow validates the strict offline PowerShell gate on Windows after an explicit dependency-prime step.
 - `.github/workflows/quality.yml` runs Checkstyle, PMD, and SpotBugs without executing tests.
 - `.github/workflows/codeql-analysis.yml` runs security analysis.
 - `.github/dependabot.yml` keeps dependency automation visible.
@@ -58,6 +59,15 @@ mvn -B test -Dtest='quality.IntegrationSuite'
 mvn -B test -Dtest='quality.PropertySuite'
 ```
 
+Run the complete PowerShell gate without network access:
+
+```powershell
+.\scripts\run-offline-gate.ps1
+```
+
+See [`TESTING.md`](TESTING.md) for strict dependency-cache mode and the documented
+cached-JUnit fallback.
+
 ## Reviewer Checklist
 
 - No hidden mutation of test inputs inside algorithmic methods.

README.md

@@ -46,6 +46,7 @@
 - **Coverage-gate**: JaCoCo ломает `mvn verify`, если покрытие ниже 70% строк, ветвлений
   или инструкций.
 - **Отдельный quality-гейт**: workflow `.github/workflows/quality.yml` для чистых статических проверок без прогона тестов.
+- **Офлайн-гейт**: Windows CI после явного заполнения кэша запускает PowerShell-проверку в строгом режиме без сети.
 - **Checkstyle / PMD / SpotBugs**: статические проверки заведены в quality-гейт.
 - **Checkstyle**: проектный набор правил в `config/checkstyle/checkstyle.xml` и явные suppressions для generated smoke-тестов.
 - **SpotBugs**: чистый отчёт с явными исключениями совместимости в `config/spotbugs-exclude.xml`.
@@ -63,6 +64,15 @@ mvn -B test -Dtest='quality.IntegrationSuite'
 mvn -B test -Dtest='quality.PropertySuite'
 ```
 
+Полный локальный прогон без сети на PowerShell:
+
+```powershell
+.\scripts\run-offline-gate.ps1
+```
+
+Подробности о строгом режиме зависимостей и fallback на уже закэшированную версию JUnit
+описаны в [`TESTING.md`](TESTING.md).
+
 ### Что отражает репозиторий как "публично привлекательный"
 
 - Есть CI с понятными этапами и артефактами (`surefire`, `jacoco`).

TESTING.md

@@ -64,20 +64,36 @@ mvn -B test -Dtest='quality.PropertySuite'
   - line coverage: 70%
   - branch coverage: 70%
   - instruction coverage: 70%
-- Current verified local baseline: 455 tests, 91.4% line coverage,
-  85.1% branch coverage and 92.7% instruction coverage.
+- Current verified local baseline: 594 tests. Coverage is enforced by the ratios above;
+  the generated HTML/XML report under `target/site/jacoco` is the source of exact values.
 - Run:
 
 ```bash
 mvn -B verify
 ```
 
+### Offline gate (PowerShell)
+
+The repository also provides a network-free local gate:
+
+```powershell
+.\scripts\run-offline-gate.ps1
+.\scripts\run-offline-gate.ps1 -Goal test
+.\scripts\run-offline-gate.ps1 -StrictDependencies
+```
+
+The script always passes Maven `--offline`. By default, when the exact JUnit BOM from
+`pom.xml` is not present locally, it warns and uses the newest cached release from the
+same major line for validation. `-StrictDependencies` disables that fallback and fails
+unless the exact dependency set is already cached.
+
 - CI uploads `target/surefire-reports` and `target/site/jacoco`.
 
 ## 6) CI matrix
 
 - Category workflow: smoke/integration/property tags (JDK 21)
 - Full verify workflow: JDK 17 and 21
+- Strict offline PowerShell gate: Windows, JDK 21 (after an explicit cache-prime step)
 - Static workflow: static checks only (JDK 21)
 
 ## 7) UI category status

scripts/run-offline-gate.ps1

@@ -0,0 +1,75 @@
+[CmdletBinding()]
+param(
+    [ValidateSet('test', 'verify')]
+    [string] $Goal = 'verify',
+
+    [switch] $StrictDependencies
+)
+
+Set-StrictMode -Version Latest
+$ErrorActionPreference = 'Stop'
+
+$repoRoot = Split-Path -Parent $PSScriptRoot
+$pomPath = Join-Path $repoRoot 'pom.xml'
+$maven = Get-Command mvn -ErrorAction Stop
+$localRepository = if ($env:MAVEN_REPO_LOCAL) {
+    $env:MAVEN_REPO_LOCAL
+} else {
+    Join-Path $env:USERPROFILE '.m2\repository'
+}
+
+[xml] $pom = Get-Content -LiteralPath $pomPath -Raw
+$configuredJUnit = [string] $pom.project.properties.'junit.version'
+$configuredPlatform = [string] $pom.project.properties.'junit.platform.version'
+$configuredBom = Join-Path $localRepository (
+    'org\junit\junit-bom\{0}\junit-bom-{0}.pom' -f $configuredJUnit
+)
+
+$mavenArguments = @(
+    '--offline'
+    '--batch-mode'
+    '--no-transfer-progress'
+    '--file'
+    $pomPath
+)
+
+if (-not (Test-Path -LiteralPath $configuredBom)) {
+    if ($StrictDependencies) {
+        throw "The configured JUnit BOM $configuredJUnit is absent from the local Maven cache."
+    }
+
+    $configuredMajor = ([version] $configuredJUnit).Major
+    $bomRoot = Join-Path $localRepository 'org\junit\junit-bom'
+    $fallback = Get-ChildItem -LiteralPath $bomRoot -Directory -ErrorAction SilentlyContinue |
+        Where-Object {
+            $_.Name -match '^\d+\.\d+\.\d+$' -and
+            ([version] $_.Name).Major -eq $configuredMajor -and
+            (Test-Path -LiteralPath (Join-Path $_.FullName ("junit-bom-{0}.pom" -f $_.Name)))
+        } |
+        Sort-Object { [version] $_.Name } -Descending |
+        Select-Object -First 1
+
+    if ($null -eq $fallback) {
+        throw "No JUnit $configuredMajor.x BOM is available in the local Maven cache."
+    }
+
+    Write-Warning ((
+            "JUnit BOM $configuredJUnit is not cached; offline validation uses cached {0}. " +
+            "Run with -StrictDependencies to require the exact POM version."
+        ) -f $fallback.Name)
+    $mavenArguments += "-Djunit.version=$($fallback.Name)"
+
+    if ($configuredPlatform -eq $configuredJUnit) {
+        $mavenArguments += "-Djunit.platform.version=$($fallback.Name)"
+    }
+}
+
+Push-Location $repoRoot
+try {
+    & $maven.Source @mavenArguments $Goal
+    if ($LASTEXITCODE -ne 0) {
+        throw "Offline Maven gate failed with exit code $LASTEXITCODE."
+    }
+} finally {
+    Pop-Location
+}

src/main/java/interview/CallbackScheduler.java

@@ -33,10 +33,23 @@ public CallbackScheduler() {
     public void schedule(Runnable callback, Instant when) {
         Objects.requireNonNull(callback);
         Objects.requireNonNull(when);
-        long delayMillis = Math.max(0L, Duration.between(Instant.now(), when).toMillis());
+        long delayMillis = delayMillisUntil(when);
         scheduler.schedule(callback, delayMillis, TimeUnit.MILLISECONDS);
     }
 
+    private static long delayMillisUntil(Instant when) {
+        Duration delay = Duration.between(Instant.now(), when);
+        if (delay.isNegative() || delay.isZero()) {
+            return 0L;
+        }
+        try {
+            return delay.toMillis();
+        } catch (ArithmeticException ignored) {
+            // Instant supports a wider range than a millisecond delay stored in a long.
+            return Long.MAX_VALUE;
+        }
+    }
+
     @Override
     public void close() {
         scheduler.shutdownNow();

src/main/java/kyu4/MorseCodeDecoder.java

@@ -4,6 +4,7 @@
 import java.util.ArrayList;
 import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.StringJoiner;
 
@@ -129,7 +130,7 @@ public static String decodeMorse(String morseCode) {
             }
             decodedWords.add(decodedWord.toString());
         }
-        return String.join(" ", decodedWords).toUpperCase();
+        return String.join(" ", decodedWords).toUpperCase(Locale.ROOT);
     }
 
     public static String encode(String toMorseCode) {
@@ -141,7 +142,7 @@ public static String encode(String toMorseCode) {
         for (String word : toMorseCode.trim().split("\\s+")) {
             StringJoiner letters = new StringJoiner(" ");
             for (char letter : word.toCharArray()) {
-                String morse = ALPHABET_TO_MORSE.get(String.valueOf(letter).toLowerCase());
+                String morse = ALPHABET_TO_MORSE.get(String.valueOf(letter).toLowerCase(Locale.ROOT));
                 if (morse == null) {
                     throw new IllegalArgumentException("Unsupported Morse character: " + letter);
                 }

src/main/java/kyu5/HumanReadableTime.java

@@ -21,8 +21,8 @@ public class HumanReadableTime {
     private static final int SIXTY = 60;
 
     public static String makeReadable(int seconds) {
-        if (seconds > 359999) {
-            throw new IllegalArgumentException("very long arguments");
+        if (seconds < 0 || seconds > 359999) {
+            throw new IllegalArgumentException("seconds must be between 0 and 359999");
         }
         int HH = 0;
         int MM = 0;

src/main/java/kyu5/MaximumSubarraySum.java

@@ -1,34 +1,21 @@
 package kyu5;
 
 
-import java.util.Arrays;
-
-
 public class MaximumSubarraySum {
 
     //5
 
     public static int sequence(int[] arr) {
-        int maximumSubArraySum = arraySum(arr);
-        for (int i = 0; i <= arr.length; i++) {
-            for (int j = arr.length; j >= i; j--) {
-                int[] ints = Arrays.copyOfRange(arr, i, j);
-                int subArraySum = arraySum(ints);
-                if (subArraySum > maximumSubArraySum) {
-                    maximumSubArraySum = subArraySum;
-                }
-            }
+        if (arr == null) {
+            throw new IllegalArgumentException("array must not be null");
         }
-        return maximumSubArraySum;
-    }
-
-    private static int arraySum(int[] arr) {
-        int result = 0;
-        for (int i : arr
-        ) {
-            result += i;
+        long best = 0L;
+        long current = 0L;
+        for (int value : arr) {
+            current = Math.max(0L, current + value);
+            best = Math.max(best, current);
         }
-        return result;
+        return Math.toIntExact(best);
     }
 
     /**

src/main/java/kyu5/NumberOfTrailingZerosOfN.java

@@ -1,32 +1,23 @@
 package kyu5;
 
 
-import java.math.BigInteger;
-
-
 public class NumberOfTrailingZerosOfN {
 
     //5 https://www.codewars.com/kata/52f787eb172a8b4ae1000a34/train/java
 
     public static int zeros(int n) {
-        return zeroOfTrailing(factorial(n));
-    }
-
-    private static int zeroOfTrailing(Long l) {
-        int count = 0;
-        while (l % 10 == 0) {
-            count++;
-            l /= 10;
+        if (n < 0) {
+            throw new IllegalArgumentException("n must not be negative");
         }
-        return count;
-    }
-
-    private static long factorial(int n) {
-        BigInteger result = BigInteger.ONE;
-        for (int i = 1; i <= n; i++) {
-            result = result.multiply(BigInteger.valueOf(i));
+        int zeroCount = 0;
+        for (int factor = 5; factor <= n; ) {
+            zeroCount += n / factor;
+            if (factor > n / 5) {
+                break;
+            }
+            factor *= 5;
         }
-        return result.longValue();
+        return zeroCount;
     }
 
 }