Accept alternate squash solution

- validate the upstream requirement of exactly two commits
- accept soft reset followed by a replacement commit
- reject resetting to one commit without creating the squashed commit
- document squash validation parity

LevelsCompare.md

@@ -115,7 +115,7 @@ This file records the upstream Ruby setup and validation intent beside the Andro
 | `cherry-pick` | Top commits are "Filled in README..." then "Added fancy branded output". | Same commit message order plus `README.md` tracked. | Equivalent. |
 | `grep` | Answer is TODO count `4`. | Answer is `4`. | Equivalent. |
 | `rename_commit` | Parent commit message is corrected to `First commit`. | No `coommit` remains and `First commit` exists; the in-app rebase editor uses the subject text on a `reword` line as the replacement message. | Equivalent outcome with a single mobile editor step. |
-| `squash` | Commit count is two. | Commit count at most two and "Adding README" remains. | Slightly stricter on preserving the base README commit. |
+| `squash` | Commit count is two. | Commit count is exactly two; interactive rebase and soft-reset/recommit solutions are accepted. | Equivalent. |
 | `merge_squash` | Commit count is three and all long-feature changes are included. | Squash action recorded and a commit exists. | Known gap: Android does not yet verify all squash file/content effects. |
 | `reorder` | `git log` subject order matches `Third.*Second.*First.*Initial`. | Modeled commit order becomes First, Second, Third. | Equivalent relative to Android's oldest-first commit list. |
 | `bisect` | Answer is hash prefix `18ed2ac` after using Ruby/make fixture. | Learner can run `git bisect start`, mark `HEAD` bad and `known-good` good, run `git bisect run ./test-balance.sh`, then answer the last good commit hash. | Same bisect lesson, different fixture and final answer target to keep the Android flow clear without Ruby/make. |

app/build.gradle.kts

@@ -19,8 +19,8 @@ android {
         applicationId = "solutions.tretter.githugandroid"
         minSdk = 26
         targetSdk = 35
-        versionCode = 169
-        versionName = "0.1.168"
+        versionCode = 170
+        versionName = "0.1.169"
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
         vectorDrawables.useSupportLibrary = true

app/src/main/java/solutions/tretter/githugandroid/levels/SquashLevel.kt

@@ -28,11 +28,19 @@ internal fun squashLevel(): Level = level(
         addCommit("Updating README (squash this commit into Adding README)", "README")
         true
     },
-    validator = repoPredicate { repo -> repo.commits.size <= 2 && repo.commits.any { it.message == "Adding README" } },
+    validator = repoPredicate { repo -> repo.commits.size == 2 },
     testCases = listOf(
         levelTestCase(
             "interactive squash",
             "GIT_SEQUENCE_EDITOR=\"sed -i '2,\$s/^pick /squash /'\" GIT_EDITOR=true git rebase -i HEAD~4",
         ),
+        levelTestCase(
+            "soft reset and recommit",
+            "git reset --soft HEAD~4",
+            "git commit -m \"New commit message\"",
+        ),
+    ),
+    negativeTestCases = listOf(
+        levelTestCase("reset without replacement commit", "git reset --soft HEAD~4"),
     ),
 )