chore(quartz): tighten fs store exception handling + lock manager

Audit cleanup — three correctness-adjacent fixes:

#13 — FsLayout.readOrCreateSeed was TOCTOU-racy for two processes
opening the same fresh directory. Both could pass `!exists()`, both
write their own random bytes, both ATOMIC_MOVE into place. Loser's
seed is forgotten but they already hashed with it, so their future
index entries would be unreachable. Switch to CREATE_NEW: exactly one
process creates the file, the other catches FileAlreadyExistsException
and falls through to read the winner's bytes.

#9 — `catch (_: Throwable)` / `catch (_: Exception)` in FsEventStore,
FsSlots, FsTombstones narrowed to `catch (_: IOException)` plus
`catch (_: JacksonException)` for JSON-parse paths. The old catches
swallowed CancellationException (hides coroutine cancellation),
OutOfMemoryError, and ThreadDeath. Now only the errors we actually
expect on a racing read are suppressed.

#1 — FsLockManager replaced synchronized+ThreadLocal+depth-counter
with a ReentrantLock. Same semantics (cross-process flock + in-process
reentry), cleaner code: the ReentrantLock handles reentry natively
via holdCount, no ThreadLocal, no manual depth bookkeeping. Release
is guarded by `holdCount == 1` on exit. Narrow catches in the
cleanup path to IOException too.

113 fs tests green across all suites.

quartz/src/jvmMain/kotlin/com/vitorpamplona/quartz/nip01Core/store/fs/FsEventStore.kt

@@ -429,7 +429,9 @@ open class FsEventStore(
                     val event =
                         try {
                             Event.fromJson(Files.readString(path))
-                        } catch (_: Exception) {
+                        } catch (_: java.io.IOException) {
+                            continue
+                        } catch (_: com.fasterxml.jackson.core.JacksonException) {
                             continue
                         }
                     indexer.link(event, path)

quartz/src/jvmMain/kotlin/com/vitorpamplona/quartz/nip01Core/store/fs/FsLayout.kt

@@ -27,7 +27,7 @@ import com.vitorpamplona.quartz.utils.sha256.sha256
 import java.nio.ByteBuffer
 import java.nio.file.Files
 import java.nio.file.Path
-import java.nio.file.StandardCopyOption
+import java.nio.file.StandardOpenOption
 import java.security.SecureRandom
 import kotlin.io.path.exists
 
@@ -162,15 +162,29 @@ internal class FsLayout(
      * Read the seed salt (creates it on first call). The seed is
      * write-once — reopening an existing store must return the same Long
      * or every previously-written index entry becomes unreachable.
+     *
+     * Concurrent first-open: two processes opening the same fresh
+     * directory simultaneously must not both write-then-use their own
+     * random seed. We use `CREATE_NEW` so exactly one process creates
+     * the file; any loser catches `FileAlreadyExistsException` and
+     * falls through to read the winner's bytes.
      */
     fun readOrCreateSeed(): Long {
         val f = root.resolve(SEED_FILE)
         if (!f.exists()) {
             val bytes = ByteArray(8)
             SecureRandom().nextBytes(bytes)
-            val tmp = Files.createTempFile(root, ".seed-", ".tmp")
-            Files.write(tmp, bytes)
-            Files.move(tmp, f, StandardCopyOption.ATOMIC_MOVE)
+            try {
+                Files
+                    .newByteChannel(
+                        f,
+                        setOf(StandardOpenOption.CREATE_NEW, StandardOpenOption.WRITE),
+                    ).use { ch ->
+                        ch.write(ByteBuffer.wrap(bytes))
+                    }
+            } catch (_: java.nio.file.FileAlreadyExistsException) {
+                // Another process won the race; fall through to read theirs.
+            }
         }
         val bytes = Files.readAllBytes(f)
         require(bytes.size == 8) { "$SEED_FILE must be exactly 8 bytes, got ${bytes.size}" }

quartz/src/jvmMain/kotlin/com/vitorpamplona/quartz/nip01Core/store/fs/FsLockManager.kt

@@ -20,38 +20,44 @@
  */
 package com.vitorpamplona.quartz.nip01Core.store.fs
 
+import java.io.IOException
 import java.nio.channels.FileChannel
 import java.nio.channels.FileLock
 import java.nio.file.Files
 import java.nio.file.Path
 import java.nio.file.StandardOpenOption
+import java.util.concurrent.locks.ReentrantLock
 
 /**
  * Cross-process write serialisation for the file-backed event store.
  *
- * Acquires an exclusive `flock(2)` on `.lock` while the body runs, so a
- * second `amy` invocation against the same directory blocks until the
- * first releases. Re-entrant for the calling thread — nested
- * `withWriteLock` calls (e.g. transaction body that calls insert) reuse
- * the existing lock instead of self-deadlocking.
+ * Two layers of mutual exclusion:
  *
- * Readers do not take this lock. The store's atomic-rename writes mean
- * readers see either the pre- or post-mutation state, never a torn
- * file. Stale `idx/` entries that point at a just-unlinked canonical
- * are tolerated by the query loop's `NoSuchFileException` handling.
+ *  - [inProcessLock] — a `ReentrantLock` serialising threads within this
+ *    JVM. Reentrant on the same thread, so nested
+ *    `withWriteLock` calls (e.g. a transaction body that calls insert)
+ *    reuse the lock instead of self-deadlocking.
+ *
+ *  - [FileChannel.lock] on `.lock` — a POSIX/Windows advisory file lock
+ *    serialising this JVM against other JVMs pointed at the same store.
+ *    Acquired once on first entry, released once on last exit (tracked
+ *    via the reentrant hold count).
+ *
+ * Readers do not take either lock. The store's atomic-rename writes
+ * mean readers see either the pre- or post-mutation state, never a
+ * torn file. Stale `idx/` entries that point at a just-unlinked
+ * canonical are tolerated by the query loop's `NoSuchFileException`
+ * handling.
  */
 internal class FsLockManager(
     root: Path,
 ) : AutoCloseable {
     private val lockPath: Path = root.resolve(LOCK_FILE)
-    private val mu = Any()
+    private val inProcessLock = ReentrantLock()
 
-    /** Per-thread re-entry depth. Allows nested `withWriteLock` calls. */
-    private val depth = ThreadLocal.withInitial { 0 }
-
-    /** Active channel + lock when depth > 0 (any thread). Held by whoever owns the lock. */
+    /** Held only while this JVM owns the file lock (depth ≥ 1). Guarded by [inProcessLock]. */
     private var channel: FileChannel? = null
-    private var lock: FileLock? = null
+    private var fileLock: FileLock? = null
 
     init {
         try {
@@ -62,60 +68,57 @@ internal class FsLockManager(
     }
 
     fun <T> withWriteLock(body: () -> T): T {
-        // Re-entrant on the same thread: just run.
-        if (depth.get() > 0) {
-            depth.set(depth.get() + 1)
+        inProcessLock.lock()
+        try {
+            // Only the outermost re-entry actually touches the file lock.
+            if (inProcessLock.holdCount == 1) {
+                val ch = FileChannel.open(lockPath, StandardOpenOption.READ, StandardOpenOption.WRITE)
+                val l =
+                    try {
+                        ch.lock() // exclusive, blocking
+                    } catch (t: Throwable) {
+                        ch.close()
+                        throw t
+                    }
+                channel = ch
+                fileLock = l
+            }
             try {
                 return body()
             } finally {
-                depth.set(depth.get() - 1)
-            }
-        }
-
-        // Cross-thread + cross-process serialisation.
-        synchronized(mu) {
-            val ch = FileChannel.open(lockPath, StandardOpenOption.READ, StandardOpenOption.WRITE)
-            val l = ch.lock() // exclusive, blocking
-            channel = ch
-            lock = l
-            depth.set(1)
-            try {
-                return body()
-            } finally {
-                depth.set(0)
-                try {
-                    l.release()
-                } catch (_: Throwable) {
-                    // ignore
+                if (inProcessLock.holdCount == 1) {
+                    releaseFileLock()
                 }
-                try {
-                    ch.close()
-                } catch (_: Throwable) {
-                    // ignore
-                }
-                channel = null
-                lock = null
             }
+        } finally {
+            inProcessLock.unlock()
         }
     }
 
     override fun close() {
-        synchronized(mu) {
-            try {
-                lock?.release()
-            } catch (_: Throwable) {
-                // ignore
-            }
-            try {
-                channel?.close()
-            } catch (_: Throwable) {
-                // ignore
-            }
-            channel = null
-            lock = null
+        inProcessLock.lock()
+        try {
+            releaseFileLock()
+        } finally {
+            inProcessLock.unlock()
         }
     }
 
+    private fun releaseFileLock() {
+        try {
+            fileLock?.release()
+        } catch (_: IOException) {
+            // best-effort during unwind
+        }
+        try {
+            channel?.close()
+        } catch (_: IOException) {
+            // best-effort during unwind
+        }
+        fileLock = null
+        channel = null
+    }
+
     companion object {
         const val LOCK_FILE = ".lock"
     }

quartz/src/jvmMain/kotlin/com/vitorpamplona/quartz/nip01Core/store/fs/FsSlots.kt

@@ -93,9 +93,9 @@ internal class FsSlots(
         if (!slot.exists()) return null
         return try {
             Event.fromJson(slot.readText())
-        } catch (_: java.nio.file.NoSuchFileException) {
+        } catch (_: java.io.IOException) {
             null
-        } catch (_: Exception) {
+        } catch (_: com.fasterxml.jackson.core.JacksonException) {
             null
         }
     }

quartz/src/jvmMain/kotlin/com/vitorpamplona/quartz/nip01Core/store/fs/FsTombstones.kt

@@ -70,9 +70,9 @@ internal class FsTombstones(
         if (!path.exists()) return null
         return try {
             Event.fromJson(path.readText()).createdAt
-        } catch (_: java.nio.file.NoSuchFileException) {
+        } catch (_: java.io.IOException) {
             null
-        } catch (_: Exception) {
+        } catch (_: com.fasterxml.jackson.core.JacksonException) {
             null
         }
     }
@@ -135,9 +135,9 @@ internal class FsTombstones(
         if (!path.exists()) return null
         return try {
             Event.fromJson(path.readText()).createdAt
-        } catch (_: java.nio.file.NoSuchFileException) {
+        } catch (_: java.io.IOException) {
             null
-        } catch (_: Exception) {
+        } catch (_: com.fasterxml.jackson.core.JacksonException) {
             null
         }
     }