fix(raft): distinguish put-with-empty-value from delete in write path

tests/bugfix_test.nim

@@ -4,6 +4,7 @@ import std/os
 import std/tables
 import ../src/barabadb/query/[parser, executor, lexer, ast]
 import ../src/barabadb/query/exec/params
+import ../src/barabadb/query/exec/dml
 import ../src/barabadb/core/types
 import ../src/barabadb/core/config
 import ../src/barabadb/storage/lsm
@@ -417,6 +418,78 @@ suite "Raft peer address parsing":
       check msg.len > 0
       check bad in msg
 
+suite "Raft put/delete encoding — empty value is not a delete":
+
+  test "PK-only INSERT yields a put pair (deleted == false, empty value)":
+    var ctx = setupCtx()
+    defer: teardown(ctx)
+    discard executeQuery(ctx, parse("CREATE TABLE pkonly (id INTEGER PRIMARY KEY)"))
+    let r = executeQuery(ctx, parse("INSERT INTO pkonly (id) VALUES (1)"))
+    check r.success
+    check r.keyValuePairs.len == 1
+    check r.keyValuePairs[0].value.len == 0
+    check r.keyValuePairs[0].deleted == false
+
+  test "DELETE yields a delete pair (deleted == true)":
+    var ctx = setupCtx()
+    defer: teardown(ctx)
+    discard executeQuery(ctx, parse("INSERT INTO users (id, name) VALUES (1, 'alice')"))
+    let r = executeQuery(ctx, parse("DELETE FROM users WHERE id = 1"))
+    check r.success
+    check r.keyValuePairs.len == 1
+    check r.keyValuePairs[0].deleted == true
+    check r.keyValuePairs[0].value.len == 0
+
+  test "UPDATE yields a put pair (deleted == false)":
+    var ctx = setupCtx()
+    defer: teardown(ctx)
+    discard executeQuery(ctx, parse("INSERT INTO users (id, name) VALUES (1, 'alice')"))
+    let r = executeQuery(ctx, parse("UPDATE users SET name = 'bob' WHERE id = 1"))
+    check r.success
+    check r.keyValuePairs.len == 1
+    check r.keyValuePairs[0].deleted == false
+    check r.keyValuePairs[0].value.len > 0
+
+  test "txn COMMIT pairs carry deleted flag for buffered writes":
+    var ctx = setupCtx()
+    defer: teardown(ctx)
+    discard executeQuery(ctx, parse("CREATE TABLE pkonly (id INTEGER PRIMARY KEY)"))
+    discard executeQuery(ctx, parse("INSERT INTO users (id, name) VALUES (1, 'alice')"))
+    discard executeQuery(ctx, parse("BEGIN"))
+    discard executeQuery(ctx, parse("INSERT INTO pkonly (id) VALUES (7)"))
+    discard executeQuery(ctx, parse("DELETE FROM users WHERE id = 1"))
+    let r = executeQuery(ctx, parse("COMMIT"))
+    check r.success
+    check r.keyValuePairs.len == 2
+    var sawPut = false
+    var sawDelete = false
+    for pair in r.keyValuePairs:
+      if pair.deleted:
+        sawDelete = true
+        check pair.value.len == 0
+      else:
+        sawPut = true
+        check pair.key == "pkonly.id=7"
+        check pair.value.len == 0  # empty value must still be a put
+    check sawPut and sawDelete
+
+  test "apply of a put with empty value keeps the PK-only row":
+    var ctx = setupCtx()
+    defer: teardown(ctx)
+    discard executeQuery(ctx, parse("CREATE TABLE pkonly (id INTEGER PRIMARY KEY)"))
+    let r = executeQuery(ctx, parse("INSERT INTO pkonly (id) VALUES (3)"))
+    check r.success
+    check r.keyValuePairs.len == 1
+    let pair = r.keyValuePairs[0]
+    # Same decode as applyCommand in src/baradadb.nim for a "put" entry.
+    let encoded = pair.key & "\x00" & cast[string](pair.value)
+    let parts = encoded.split("\x00")
+    check parts.len >= 2
+    applyReplicatedPut(ctx, parts[0], cast[seq[byte]](parts[1]))
+    let sel = executeQuery(ctx, parse("SELECT * FROM pkonly WHERE id = 3"))
+    check sel.success
+    check sel.rows.len == 1
+
 suite "Raft write classification":
 
   test "isWrite classifies DML and COMMIT":

tests/raft_failover_load_e2e_test.nim

@@ -7,16 +7,6 @@
 ##                     follower has caught up.
 ## Process-management conventions follow tests/raft_writes_e2e_test.nim;
 ## client access follows tests/nimforum_smoke_test.nim.
-##
-## NOTE: load_test deliberately has a non-PK column. A table whose only
-## column is the PK stores an EMPTY LSM value per row (execInsert drops PK
-## columns from the value), and the raft write path (appendWriteToRaft in
-## src/barabadb/core/server.nim) encodes empty values as "delete" entries —
-## so on commit every node applies a delete over the just-inserted row and
-## it vanishes everywhere. That is a v1.2.0 product bug in the raft entry
-## encoding (put/delete must not be inferred from value emptiness); until it
-## is fixed in src/, this test exercises the two-column row shape that the
-## current encoding handles correctly.
 import std/unittest
 import std/osproc
 import std/os
@@ -176,7 +166,7 @@ proc writerLoop(args: WriterArgs) {.thread.} =
         sleep(50)
         continue
     try:
-      db.exec(sql("INSERT INTO load_test (id, n) VALUES (" & $n & ", " & $n & ")"))
+      db.exec(sql("INSERT INTO load_test (id) VALUES (" & $n & ")"))
       withLock args.lock[]:
         args.acked[].add n
       inc n
@@ -290,7 +280,7 @@ proc runFailoverLoadScenario() =
     block:
       let db = openClient(nodes[leaderIdx].clientPort)
       try:
-        db.exec(sql"CREATE TABLE load_test (id INT PRIMARY KEY, n INT)")
+        db.exec(sql"CREATE TABLE load_test (id INT PRIMARY KEY)")
       except CatchableError as e:
         echo "leader CREATE TABLE failed: ", e.msg
         dumpAll(nodes)
@@ -343,7 +333,7 @@ proc runFailoverLoadScenario() =
         try:
           let db = openClient(nodes[i].clientPort)
           try:
-            db.exec(sql("INSERT INTO load_test (id, n) VALUES (" & $probeId & ", " & $probeId & ")"))
+            db.exec(sql("INSERT INTO load_test (id) VALUES (" & $probeId & ")"))
             writerSurvivor = i
           finally:
             db.close()

tests/test_all.nim

@@ -2670,7 +2670,7 @@ suite "Raft SQL Write Path":
 
         # Server-side leader write path: append + wait for majority commit
         let (ok, errMsg) = waitFor appendWriteToRaft(leader,
-          @[("users.1", cast[seq[byte]]("alice"))], timeoutMs = 3000)
+          @[("users.1", cast[seq[byte]]("alice"), false)], timeoutMs = 3000)
         check ok
         if not ok: echo "appendWriteToRaft failed: ", errMsg
 
@@ -2782,7 +2782,7 @@ suite "Raft SQL Write Path":
     var n = newRaftNode("n1", @["n2"], raftPort = 29111)
     # Still a follower — appendLog returns index 0.
     let (ok, err) = waitFor appendWriteToRaft(n,
-      @[("k", cast[seq[byte]]("v"))], timeoutMs = 200)
+      @[("k", cast[seq[byte]]("v"), false)], timeoutMs = 200)
     check not ok
     check "lost leadership" in err
 
@@ -2791,7 +2791,7 @@ suite "Raft SQL Write Path":
     var n = newRaftNode("n1", @["n2", "n3"], raftPort = 29112)
     n.becomeLeader()
     let (ok, err) = waitFor appendWriteToRaft(n,
-      @[("k", cast[seq[byte]]("v"))], timeoutMs = 300)
+      @[("k", cast[seq[byte]]("v"), false)], timeoutMs = 300)
     check not ok
     check "raft commit timeout" in err