diff --git a/desktopApp/build.gradle.kts b/desktopApp/build.gradle.kts
index c59128bc26..33305830b2 100644
--- a/desktopApp/build.gradle.kts
+++ b/desktopApp/build.gradle.kts
@@ -1,6 +1,7 @@
 import de.undercouch.gradle.tasks.download.Download
 import org.jetbrains.compose.desktop.application.dsl.TargetFormat
 import java.nio.file.Files
+import java.util.zip.ZipFile
 
 plugins {
     alias(libs.plugins.jetbrainsKotlinJvm)
@@ -273,3 +274,76 @@ val createReleaseAppImage by tasks.registering(Exec::class) {
     // AppImage standard env var: extracts + runs without mounting.
     environment("APPIMAGE_EXTRACT_AND_RUN", "1")
 }
+
+// ============================================================================
+// Native lib regression guard
+// ============================================================================
+// `pt.davidafsilva.apple:jkeychain` ships its `osxkeychain.so` native library
+// as a resource at the JAR root, and `OSXKeychain.loadSharedObject()` reaches
+// it with `getResourceAsStream("/osxkeychain.so")`. If a future ProGuard
+// upgrade, dep swap, or build-config change strips this resource from the
+// release distributable, every macOS user is forced back to the login screen
+// on every cold boot (the Keychain backend can't load, `SecureKeyStorage`
+// falls back to its password-prompted encrypted file, which never prompts
+// in a GUI cold boot → keys silently null → bunker / nsec / NWC unrecoverable).
+//
+// As of the current build the resource DOES survive ProGuard (it ships in the
+// proguarded jkeychain-1.1.0-*.jar with all 117 KB intact), so this task is
+// a regression guard, not a workaround. It's wired onto every release task so
+// it fails the build immediately if the .so disappears.
+val verifyJkeychainNativeSurvivesProguard by tasks.registering {
+    description = "Fail the release build if osxkeychain.so is stripped from proguarded output (would break macOS Keychain at runtime)"
+    group = "verification"
+    dependsOn("proguardReleaseJars")
+    val proguardDir = layout.buildDirectory.dir("compose/tmp/main-release/proguard")
+    inputs.dir(proguardDir).withPropertyName("proguardOutput").withPathSensitivity(PathSensitivity.RELATIVE)
+    val marker = layout.buildDirectory.file("verify-jkeychain-native.ok")
+    outputs.file(marker)
+    doLast {
+        val dir = proguardDir.get().asFile
+        require(dir.isDirectory) { "ProGuard output dir missing: $dir" }
+        val jars = dir.listFiles { f -> f.extension == "jar" } ?: emptyArray()
+        require(jars.isNotEmpty()) { "No proguarded jars under $dir" }
+        val foundIn = jars.firstOrNull { jar ->
+            val zip = ZipFile(jar)
+            try {
+                val entries = zip.entries()
+                var found = false
+                while (entries.hasMoreElements()) {
+                    if (entries.nextElement().name == "osxkeychain.so") {
+                        found = true
+                        break
+                    }
+                }
+                found
+            } finally {
+                zip.close()
+            }
+        }
+        require(foundIn != null) {
+            "REGRESSION: osxkeychain.so missing from every proguarded jar in $dir.\n" +
+                "OSXKeychain.loadSharedObject() calls getResourceAsStream(\"/osxkeychain.so\") — if this\n" +
+                "resource is not at classpath root in the release distributable, every macOS user is\n" +
+                "forced to re-log-in on every cold boot of the release DMG."
+        }
+        marker.get().asFile.writeText("verified osxkeychain.so survived ProGuard in ${foundIn.name}\n")
+        println("verifyJkeychainNativeSurvivesProguard: osxkeychain.so present in ${foundIn.name}")
+    }
+}
+
+// Gate every release-packaging task on the verification so a stripped .so
+// never reaches a release artifact.
+listOf(
+    "packageReleaseDmg",
+    "packageReleaseMsi",
+    "packageReleaseDeb",
+    "packageReleaseRpm",
+    "packageReleaseDistributionForCurrentOS",
+    "packageReleaseUberJarForCurrentOS",
+    "createReleaseDistributable",
+    "runReleaseDistributable",
+).forEach { name ->
+    tasks.matching { it.name == name }.configureEach {
+        dependsOn(verifyJkeychainNativeSurvivesProguard)
+    }
+}
diff --git a/docs/plans/2026-06-18-fix-desktop-macos-bunker-relogin-plan.md b/docs/plans/2026-06-18-fix-desktop-macos-bunker-relogin-plan.md
index 867cd807bc..006f054a84 100644
--- a/docs/plans/2026-06-18-fix-desktop-macos-bunker-relogin-plan.md
+++ b/docs/plans/2026-06-18-fix-desktop-macos-bunker-relogin-plan.md
@@ -19,16 +19,28 @@ origin: docs/brainstorms/2026-06-18-fix-macos-bunker-relogin-brainstorm.md
 **Reverted in PR 1:**
 - ❌ ProGuard keep-rule change — the hypothesis it was based on is refuted by binary PoW; the original `pt.davidafsilva.apple.**` keep is correct and stays in place.
 
-**Open — actual root cause still unidentified.** Working hypotheses:
-- **H2 — Hardened runtime blocks unsigned dylib load.** `OSXKeychain.loadSharedObject()` extracts `libosxkeychain.dylib` to `/tmp` and `System.load()`s it. Hardened-runtime + Gatekeeper on a notarized DMG **rejects loading an unsigned dylib at runtime** unless the app entitlements include `com.apple.security.cs.disable-library-validation`. Dev `./gradlew :desktopApp:run` doesn't apply hardened runtime — explains the dev-works / release-fails split.
-- **H4 — jpackage strips the dylib resource.** Compose-Multiplatform's jpackage path could re-pack jars without preserving `META-INF/native/*` or resource-style `.dylib` files. Worth examining the DMG bundle structure.
-- **H5 — pre-hardening accounts.json.enc migration gap.** If user installed `v1.11.0` then upgraded, the migration from `bunker_uri.txt` → `accounts.json.enc` (commit `46caa4d79`) might leave the bunker entry missing. But this would not happen "every restart, always" — it would happen ONCE post-upgrade. Lower likelihood.
+**Open — actual root cause still unidentified after three refuted hypotheses.**
 
-**Verification plan (still needs a Mac + ideally the affected user):**
-- `./gradlew :desktopApp:packageReleaseDmg` locally, install, log in with bunker, quit, relaunch — DOES the bug reproduce on a locally-built (unsigned) DMG?
-- If reproduces on unsigned DMG → not hardened runtime, look at jpackage stripping.
-- If only reproduces on signed/notarized DMG → H2 is the answer; fix is `--mac-entitlements` or `--mac-hardened-runtime` flag config.
-- `codesign --display --entitlements - /Applications/Amethyst.app` on the affected user's installed DMG to see what entitlements were actually applied.
+### PoW logs from 2026-06-18 / 06-19 investigation
+
+| # | Hypothesis | Test | Result |
+|---|------------|------|--------|
+| H1 | ProGuard strips macOS keychain backend classes | `javap` on `OsxKeychainBackend.class` + `ModernOsxKeychainBackend.class` in proguarded vs unshrunk jar | **REFUTED** — bytecode identical, all native methods preserved |
+| H1b | ProGuard strips `osxkeychain.so` native resource | `unzip -l desktopApp/build/compose/tmp/main-release/proguard/jkeychain-1.1.0-*.jar` | **REFUTED** — file present, 117016 bytes |
+| H2 | Hardened runtime + Library Validation blocks unsigned dylib load | `codesign -d --entitlements -` on locally-built `Amethyst.app` | **REFUTED** — `com.apple.security.cs.disable-library-validation = true` is present in default entitlements |
+| — | `Keyring.create()` + `setPassword` + `getPassword` round-trip on macOS Keychain | Java program run with `java -cp <proguarded jars> KeychainTest` | **PASS** — round-trip succeeds against proguarded classpath on this host |
+| — | Locally-built release distributable launches | `./Amethyst.app/Contents/MacOS/Amethyst` foreground for 10s | **OK** — only unrelated VLC plugin-cache warnings on stderr |
+
+**What this means:** the bug cannot be reproduced on a locally-built (unsigned, adhoc-signed) release distributable on this Apple Silicon Mac. Either:
+- The bug requires the actual CI-built release DMG (something in CI's environment / jpackage runtime differs from local)
+- Or the bug is environment-specific to the affected user (macOS version, prior Keychain state, quarantine xattrs, an upgrade path we haven't replicated)
+- Or there's a different code path (not keychain) that breaks on cold boot for bunker accounts specifically
+
+**Next investigation steps need a Mac + the affected user:**
+- Affected user: `Console.app` filter "Amethyst", attempt bunker login, force-quit, relaunch — share log lines.
+- Affected user: `security find-generic-password -s amethyst-desktop` immediately after first bunker login — does the entry exist?
+- Affected user: `ls -la ~/.amethyst/` — does `accounts.json.enc` contain a bunker entry after first login?
+- Mac reviewer: download the *signed/notarized* GitHub release DMG, install, repro on a clean macOS user account.
 
 # 🐛 fix(desktop): macOS forced re-login on cold boot — ProGuard strips java-keyring backend