diff --git a/api/internal/bitcoind/rpc_test.go b/api/internal/bitcoind/rpc_test.go
new file mode 100644
index 0000000..d21f661
--- /dev/null
+++ b/api/internal/bitcoind/rpc_test.go
@@ -0,0 +1,213 @@
+package bitcoind
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"sync/atomic"
+	"testing"
+	"time"
+)
+
+// ---- isRetryable unit tests ----
+
+func TestIsRetryable_TransportErrors(t *testing.T) {
+	cases := []struct {
+		err  error
+		want bool
+	}{
+		{fmt.Errorf("bitcoind rpc: connection refused"), true},
+		{fmt.Errorf("bitcoind rpc: connection reset by peer"), true},
+		{fmt.Errorf("bitcoind rpc: EOF"), true},
+		{fmt.Errorf("bitcoind rpc: i/o timeout"), true},
+		{fmt.Errorf("bitcoind rpc: deadline exceeded"), true},
+		{fmt.Errorf("bitcoind rpc: broken pipe"), true},
+		{fmt.Errorf("bitcoind rpc: 503: service unavailable"), true},
+		{fmt.Errorf("bitcoind rpc: 502: bad gateway"), true},
+	}
+	for _, tc := range cases {
+		if got := isRetryable(tc.err); got != tc.want {
+			t.Errorf("isRetryable(%q) = %v, want %v", tc.err, got, tc.want)
+		}
+	}
+}
+
+func TestIsRetryable_WarmupRPCError(t *testing.T) {
+	warmup := &rpcError{Code: -28, Message: "Loading block index"}
+	if !isRetryable(warmup) {
+		t.Error("warmup error (-28) should be retryable")
+	}
+
+	msgOnly := &rpcError{Code: -1, Message: "Bitcoin is warming up"}
+	if !isRetryable(msgOnly) {
+		t.Error("'warming up' message should be retryable")
+	}
+}
+
+func TestIsRetryable_SemanticRPCError(t *testing.T) {
+	blockNotFound := &rpcError{Code: -5, Message: "Block not found"}
+	if isRetryable(blockNotFound) {
+		t.Error("block-not-found (-5) should NOT be retryable")
+	}
+
+	invalidParam := &rpcError{Code: -1, Message: "Invalid parameter"}
+	if isRetryable(invalidParam) {
+		t.Error("invalid-parameter should NOT be retryable")
+	}
+}
+
+func TestIsRetryable_Nil(t *testing.T) {
+	if isRetryable(nil) {
+		t.Error("nil should not be retryable")
+	}
+}
+
+// ---- Call retry integration tests ----
+
+// jsonRPCServer starts an httptest server that counts requests and serves the
+// provided response JSON. If failFirst > 0, the first failFirst requests
+// return HTTP 503 before that.
+func jsonRPCServer(t *testing.T, failFirst int, result any) (*httptest.Server, *int32) {
+	t.Helper()
+	var calls int32
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		n := atomic.AddInt32(&calls, 1)
+		if int(n) <= failFirst {
+			w.WriteHeader(http.StatusServiceUnavailable)
+			return
+		}
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(map[string]any{"result": result, "error": nil})
+	}))
+	t.Cleanup(srv.Close)
+	return srv, &calls
+}
+
+func TestCall_SuccessOnFirstTry(t *testing.T) {
+	srv, calls := jsonRPCServer(t, 0, "blockhash_abc")
+	rpc := NewRPC(srv.URL, "u", "p", 5*time.Second)
+
+	var out string
+	if err := rpc.Call(context.Background(), "getblockhash", []any{100}, &out); err != nil {
+		t.Fatalf("Call: %v", err)
+	}
+	if out != "blockhash_abc" {
+		t.Errorf("result = %q, want blockhash_abc", out)
+	}
+	if n := atomic.LoadInt32(calls); n != 1 {
+		t.Errorf("calls = %d, want 1", n)
+	}
+}
+
+func TestCall_RetryOnTransient503(t *testing.T) {
+	srv, calls := jsonRPCServer(t, 2, "blockhash_xyz")
+	rpc := NewRPC(srv.URL, "u", "p", 5*time.Second)
+
+	var out string
+	if err := rpc.Call(context.Background(), "getblockhash", []any{200}, &out); err != nil {
+		t.Fatalf("Call failed after retries: %v", err)
+	}
+	if out != "blockhash_xyz" {
+		t.Errorf("result = %q, want blockhash_xyz", out)
+	}
+	// First 2 calls fail, third succeeds.
+	if n := atomic.LoadInt32(calls); n != 3 {
+		t.Errorf("calls = %d, want 3", n)
+	}
+}
+
+func TestCall_ExhaustsRetries(t *testing.T) {
+	// Server always returns 503 — all 3 attempts should fail.
+	srv, calls := jsonRPCServer(t, 99, nil)
+	rpc := NewRPC(srv.URL, "u", "p", 5*time.Second)
+
+	var out string
+	if err := rpc.Call(context.Background(), "getblockhash", []any{300}, &out); err == nil {
+		t.Fatal("expected error after exhausted retries, got nil")
+	}
+	if n := atomic.LoadInt32(calls); n != 3 {
+		t.Errorf("calls = %d, want 3 (maxAttempts)", n)
+	}
+}
+
+func TestCall_NoRetryOnSemanticRPCError(t *testing.T) {
+	// Server returns a semantic RPC error (block not found). Should not be
+	// retried — the answer is definitive.
+	var calls int32
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		atomic.AddInt32(&calls, 1)
+		json.NewEncoder(w).Encode(map[string]any{
+			"result": nil,
+			"error":  map[string]any{"code": -5, "message": "Block not found"},
+		})
+	}))
+	t.Cleanup(srv.Close)
+
+	rpc := NewRPC(srv.URL, "u", "p", 5*time.Second)
+	var out string
+	err := rpc.Call(context.Background(), "getblockhash", []any{999}, &out)
+	if err == nil {
+		t.Fatal("expected error, got nil")
+	}
+	if n := atomic.LoadInt32(&calls); n != 1 {
+		t.Errorf("calls = %d, want 1 (no retry on -5)", n)
+	}
+}
+
+func TestCall_RetryOnWarmup(t *testing.T) {
+	var calls int32
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		n := atomic.AddInt32(&calls, 1)
+		if n == 1 {
+			json.NewEncoder(w).Encode(map[string]any{
+				"result": nil,
+				"error":  map[string]any{"code": -28, "message": "Loading block index"},
+			})
+			return
+		}
+		json.NewEncoder(w).Encode(map[string]any{"result": "warmup_hash", "error": nil})
+	}))
+	t.Cleanup(srv.Close)
+
+	rpc := NewRPC(srv.URL, "u", "p", 5*time.Second)
+	var out string
+	if err := rpc.Call(context.Background(), "getblockhash", []any{1}, &out); err != nil {
+		t.Fatalf("Call: %v", err)
+	}
+	if out != "warmup_hash" {
+		t.Errorf("result = %q, want warmup_hash", out)
+	}
+	if n := atomic.LoadInt32(&calls); n != 2 {
+		t.Errorf("calls = %d, want 2", n)
+	}
+}
+
+// ---- CoinbaseReward unit test ----
+
+func TestCoinbaseReward(t *testing.T) {
+	blk := &BlockVerbose2{
+		Tx: []BlockTx{
+			{
+				Vout: []BlockVout{
+					{Value: 3.125},
+					{Value: 0.00042},
+				},
+			},
+			// Non-coinbase tx; should be ignored.
+			{Vout: []BlockVout{{Value: 99}}},
+		},
+	}
+	want := 3.125 + 0.00042
+	if got := blk.CoinbaseReward(); got != want {
+		t.Errorf("CoinbaseReward = %v, want %v", got, want)
+	}
+}
+
+func TestCoinbaseReward_EmptyBlock(t *testing.T) {
+	blk := &BlockVerbose2{}
+	if got := blk.CoinbaseReward(); got != 0 {
+		t.Errorf("empty block CoinbaseReward = %v, want 0", got)
+	}
+}
diff --git a/api/internal/logmon/tailer_test.go b/api/internal/logmon/tailer_test.go
new file mode 100644
index 0000000..c26bd62
--- /dev/null
+++ b/api/internal/logmon/tailer_test.go
@@ -0,0 +1,296 @@
+package logmon
+
+import (
+	"context"
+	"io"
+	"log/slog"
+	"os"
+	"sync"
+	"testing"
+	"time"
+)
+
+func discardLog() *slog.Logger {
+	return slog.New(slog.NewTextHandler(io.Discard, nil))
+}
+
+// ---- handleLine unit tests (no filesystem, no goroutines) ----
+
+func TestHandleLine_Solved(t *testing.T) {
+	tl := New("/unused", discardLog())
+	tl.handleLine("Solved and confirmed block 840123\n")
+	select {
+	case ev := <-tl.Events:
+		if ev.Height != 840123 {
+			t.Errorf("Height = %d, want 840123", ev.Height)
+		}
+	default:
+		t.Fatal("no BlockEvent emitted for solved line")
+	}
+}
+
+func TestHandleLine_AttemptCarriedToBlock(t *testing.T) {
+	tl := New("/unused", discardLog())
+	tl.handleLine("Possible block solve diff 32768 !\n")
+	tl.handleLine("Solved and confirmed block 900000\n")
+
+	select {
+	case <-tl.Attempts:
+	default:
+		t.Fatal("no AttemptEvent emitted for attempt line")
+	}
+	select {
+	case ev := <-tl.Events:
+		if ev.ShareDiff != 32768 {
+			t.Errorf("ShareDiff = %v, want 32768", ev.ShareDiff)
+		}
+		if ev.Height != 900000 {
+			t.Errorf("Height = %d, want 900000", ev.Height)
+		}
+	default:
+		t.Fatal("no BlockEvent emitted")
+	}
+}
+
+func TestHandleLine_SubmittingVariant(t *testing.T) {
+	tl := New("/unused", discardLog())
+	tl.handleLine("Submitting possible block solve share diff 65536 !\n")
+	select {
+	case ev := <-tl.Attempts:
+		if ev.ShareDiff != 65536 {
+			t.Errorf("ShareDiff = %v, want 65536", ev.ShareDiff)
+		}
+	default:
+		t.Fatal("no AttemptEvent for submitting variant")
+	}
+	// Must NOT also emit a BlockEvent.
+	select {
+	case ev := <-tl.Events:
+		t.Errorf("unexpected BlockEvent from attempt line: %+v", ev)
+	default:
+	}
+}
+
+func TestHandleLine_DiffResetAfterBlock(t *testing.T) {
+	tl := New("/unused", discardLog())
+	tl.handleLine("Possible block solve diff 16384 !\n")
+	tl.handleLine("Solved and confirmed block 100\n")
+	// Second block — no preceding attempt line; diff must NOT carry over.
+	tl.handleLine("Solved and confirmed block 101\n")
+
+	drain := func() BlockEvent {
+		select {
+		case ev := <-tl.Events:
+			return ev
+		default:
+			t.Fatal("no BlockEvent")
+			return BlockEvent{}
+		}
+	}
+	ev100 := drain()
+	ev101 := drain()
+	if ev100.ShareDiff != 16384 {
+		t.Errorf("block 100 ShareDiff = %v, want 16384", ev100.ShareDiff)
+	}
+	if ev101.ShareDiff != 0 {
+		t.Errorf("block 101 ShareDiff = %v, want 0 (no preceding attempt)", ev101.ShareDiff)
+	}
+}
+
+func TestHandleLine_Unrelated(t *testing.T) {
+	tl := New("/unused", discardLog())
+	for _, line := range []string{
+		"Stratifier started\n",
+		"New block hash 000000abc\n",
+		"Worker authenticated\n",
+	} {
+		tl.handleLine(line)
+	}
+	select {
+	case ev := <-tl.Events:
+		t.Errorf("unexpected BlockEvent from unrelated line: %+v", ev)
+	default:
+	}
+	select {
+	case ev := <-tl.Attempts:
+		t.Errorf("unexpected AttemptEvent from unrelated line: %+v", ev)
+	default:
+	}
+}
+
+// ---- Tailer.Run integration tests (filesystem + goroutines) ----
+
+func tempLog(t *testing.T) string {
+	t.Helper()
+	f, err := os.CreateTemp("", "ckpool*.log")
+	if err != nil {
+		t.Fatal(err)
+	}
+	f.Close()
+	t.Cleanup(func() { _ = os.Remove(f.Name()) })
+	return f.Name()
+}
+
+func appendLines(t *testing.T, path string, lines ...string) {
+	t.Helper()
+	f, err := os.OpenFile(path, os.O_APPEND|os.O_WRONLY, 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer f.Close()
+	for _, l := range lines {
+		if _, err := f.WriteString(l); err != nil {
+			t.Fatal(err)
+		}
+	}
+}
+
+// TestTailerRun_BasicRead starts the tailer on an empty file, appends log
+// lines, and verifies the expected events are emitted.
+func TestTailerRun_BasicRead(t *testing.T) {
+	path := tempLog(t)
+	tl := New(path, discardLog())
+	tl.PollWait = 20 * time.Millisecond
+
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+	defer cancel()
+	go tl.Run(ctx)
+
+	// Give the tailer time to open the empty file and park at EOF.
+	time.Sleep(40 * time.Millisecond)
+
+	appendLines(t, path,
+		"Possible block solve diff 16384 !\n",
+		"Solved and confirmed block 100\n",
+	)
+
+	select {
+	case <-tl.Attempts:
+	case <-ctx.Done():
+		t.Fatal("timed out waiting for AttemptEvent")
+	}
+	select {
+	case ev := <-tl.Events:
+		if ev.Height != 100 {
+			t.Errorf("Height = %d, want 100", ev.Height)
+		}
+		if ev.ShareDiff != 16384 {
+			t.Errorf("ShareDiff = %v, want 16384", ev.ShareDiff)
+		}
+	case <-ctx.Done():
+		t.Fatal("timed out waiting for BlockEvent")
+	}
+}
+
+// TestTailerRun_CursorResume verifies that a new tailer honours a saved
+// cursor and does not re-emit lines that were already processed.
+func TestTailerRun_CursorResume(t *testing.T) {
+	path := tempLog(t)
+
+	var mu sync.Mutex
+	var savedIno uint64
+	var savedOff int64
+
+	tl := New(path, discardLog())
+	tl.PollWait = 20 * time.Millisecond
+	tl.SaveCursor = func(ino uint64, off int64) {
+		mu.Lock()
+		savedIno, savedOff = ino, off
+		mu.Unlock()
+	}
+
+	ctx1, cancel1 := context.WithTimeout(context.Background(), 3*time.Second)
+	go tl.Run(ctx1)
+	time.Sleep(40 * time.Millisecond)
+
+	// Phase 1: write 2 blocks and drain both events.
+	appendLines(t, path,
+		"Solved and confirmed block 200\n",
+		"Solved and confirmed block 201\n",
+	)
+	for i := 0; i < 2; i++ {
+		select {
+		case <-tl.Events:
+		case <-ctx1.Done():
+			t.Fatalf("phase 1: only got %d events, want 2", i)
+		}
+	}
+	// Allow the tailer to hit EOF and save the cursor.
+	time.Sleep(100 * time.Millisecond)
+	cancel1()
+	// Give the goroutine time to exit and force-save.
+	time.Sleep(60 * time.Millisecond)
+
+	mu.Lock()
+	ino, off := savedIno, savedOff
+	mu.Unlock()
+	if ino == 0 {
+		t.Fatal("cursor was never saved after phase 1")
+	}
+
+	// Phase 2: append a third block, start a new tailer from the cursor.
+	// It must see ONLY block 202, not replays of 200 or 201.
+	appendLines(t, path, "Solved and confirmed block 202\n")
+
+	tl2 := New(path, discardLog())
+	tl2.PollWait = 20 * time.Millisecond
+	tl2.LoadCursor = func() (uint64, int64, bool) { return ino, off, true }
+
+	ctx2, cancel2 := context.WithTimeout(context.Background(), 3*time.Second)
+	defer cancel2()
+	go tl2.Run(ctx2)
+
+	select {
+	case ev := <-tl2.Events:
+		if ev.Height != 202 {
+			t.Errorf("resumed tailer emitted height %d, want 202 (cursor resume may be broken)", ev.Height)
+		}
+	case <-ctx2.Done():
+		t.Fatal("timed out waiting for block 202 after cursor resume")
+	}
+}
+
+// TestTailerRun_Rotation verifies that when the log file is replaced
+// (inode changes), the tailer re-opens it from the start and reads the
+// new content.
+func TestTailerRun_Rotation(t *testing.T) {
+	path := tempLog(t)
+	tl := New(path, discardLog())
+	tl.PollWait = 30 * time.Millisecond
+
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+	go tl.Run(ctx)
+	time.Sleep(50 * time.Millisecond)
+
+	// Write a block to the original file and collect it.
+	appendLines(t, path, "Solved and confirmed block 300\n")
+	select {
+	case ev := <-tl.Events:
+		if ev.Height != 300 {
+			t.Errorf("before rotation: height = %d, want 300", ev.Height)
+		}
+	case <-ctx.Done():
+		t.Fatal("timed out waiting for pre-rotation block")
+	}
+
+	// Simulate log rotation: replace the file at the same path.
+	newF, err := os.CreateTemp("", "ckpool_new*.log")
+	if err != nil {
+		t.Fatal(err)
+	}
+	newF.WriteString("Solved and confirmed block 301\n")
+	newF.Close()
+	if err := os.Rename(newF.Name(), path); err != nil {
+		t.Fatal(err)
+	}
+
+	select {
+	case ev := <-tl.Events:
+		if ev.Height != 301 {
+			t.Errorf("after rotation: height = %d, want 301", ev.Height)
+		}
+	case <-ctx.Done():
+		t.Fatal("timed out waiting for post-rotation block")
+	}
+}
diff --git a/api/internal/state/blocks_test.go b/api/internal/state/blocks_test.go
new file mode 100644
index 0000000..0d1c77e
--- /dev/null
+++ b/api/internal/state/blocks_test.go
@@ -0,0 +1,378 @@
+package state
+
+import (
+	"context"
+	"encoding/json"
+	"io"
+	"log/slog"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/kamadopool/kamado-api/internal/bitcoind"
+	"github.com/kamadopool/kamado-api/internal/logmon"
+	"github.com/kamadopool/kamado-api/internal/store"
+)
+
+func discardLog() *slog.Logger {
+	return slog.New(slog.NewTextHandler(io.Discard, nil))
+}
+
+func openTempStore(t *testing.T) *store.BlockStore {
+	t.Helper()
+	f, err := os.CreateTemp("", "state_test*.db")
+	if err != nil {
+		t.Fatal(err)
+	}
+	f.Close()
+	t.Cleanup(func() { _ = os.Remove(f.Name()) })
+	s, err := store.Open(f.Name())
+	if err != nil {
+		t.Fatalf("store.Open: %v", err)
+	}
+	t.Cleanup(func() { _ = s.Close() })
+	return s
+}
+
+// mockRPC starts an httptest server whose responses are determined by the
+// supplied handler. The handler receives the RPC method name and the raw
+// params JSON and returns the value to place in "result". Returning nil
+// sends an empty result; returning a non-nil error (as rpcErrResp) sends
+// an RPC error response.
+type rpcErrResp struct {
+	Code    int
+	Message string
+}
+
+func mockRPC(t *testing.T, handler func(method string) (any, *rpcErrResp)) *bitcoind.RPC {
+	t.Helper()
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		var req struct {
+			Method string `json:"method"`
+		}
+		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+			http.Error(w, err.Error(), 400)
+			return
+		}
+		result, rpcErr := handler(req.Method)
+		if rpcErr != nil {
+			json.NewEncoder(w).Encode(map[string]any{
+				"result": nil,
+				"error":  map[string]any{"code": rpcErr.Code, "message": rpcErr.Message},
+			})
+			return
+		}
+		json.NewEncoder(w).Encode(map[string]any{"result": result, "error": nil})
+	}))
+	t.Cleanup(srv.Close)
+	return bitcoind.NewRPC(srv.URL, "u", "p", 5*time.Second)
+}
+
+func newAgg(st *store.BlockStore, rpc *bitcoind.RPC) *Aggregator {
+	return &Aggregator{
+		Store: st,
+		RPC:   rpc,
+		Log:   discardLog(),
+		ready: make(chan struct{}),
+	}
+}
+
+// setChain sets the aggregator's snapshot chain without going through refresh.
+func setChain(agg *Aggregator, chain string) {
+	agg.mu.Lock()
+	agg.snap.Chain = &bitcoind.BlockchainInfo{Chain: chain}
+	agg.mu.Unlock()
+}
+
+// ---- reconcileOnce tests ----
+
+// TestReconcileOnce_ChainFilter verifies that a block recorded on testnet
+// is NOT orphaned when the node is now on mainnet — even if the canonical
+// hash at that height on mainnet is different.
+func TestReconcileOnce_ChainFilter_NoFalseOrphan(t *testing.T) {
+	st := openTempStore(t)
+
+	// Insert a testnet block with a known hash.
+	_, err := st.InsertBlock(store.Block{
+		Height:   100,
+		Hash:     "testnet_hash_aaa",
+		RewardBT: 50,
+		FoundAt:  time.Now(),
+		Source:   "test",
+		Chain:    "test",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Mock RPC returns a DIFFERENT hash for height 100 — mainnet canonical.
+	rpc := mockRPC(t, func(method string) (any, *rpcErrResp) {
+		if method == "getblockhash" {
+			return "mainnet_hash_bbb", nil
+		}
+		return nil, nil
+	})
+
+	agg := newAgg(st, rpc)
+	setChain(agg, "main") // switched to mainnet
+
+	agg.reconcileOnce(context.Background())
+
+	blocks, err := st.Recent(10)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, b := range blocks {
+		if b.Height == 100 && !b.OrphanedAt.IsZero() {
+			t.Error("testnet block was falsely orphaned after switching to mainnet — chain filter broken")
+		}
+	}
+}
+
+// TestReconcileOnce_GenuineReorg verifies that when the canonical block at a
+// recorded height has a different hash (real on-chain reorg), the block is
+// marked orphaned.
+func TestReconcileOnce_GenuineReorg(t *testing.T) {
+	st := openTempStore(t)
+
+	_, err := st.InsertBlock(store.Block{
+		Height:   200,
+		Hash:     "our_hash_aaaa",
+		RewardBT: 3.125,
+		FoundAt:  time.Now(),
+		Source:   "test",
+		Chain:    "main",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	rpc := mockRPC(t, func(method string) (any, *rpcErrResp) {
+		if method == "getblockhash" {
+			return "canonical_bbbb", nil // different — reorg happened
+		}
+		return nil, nil
+	})
+
+	agg := newAgg(st, rpc)
+	setChain(agg, "main")
+
+	agg.reconcileOnce(context.Background())
+
+	blocks, err := st.Recent(10)
+	if err != nil {
+		t.Fatal(err)
+	}
+	found := false
+	for _, b := range blocks {
+		if b.Height == 200 {
+			found = true
+			if b.OrphanedAt.IsZero() {
+				t.Error("block at reorged height was not marked orphaned")
+			}
+		}
+	}
+	if !found {
+		t.Error("block 200 not found in store after reconcile")
+	}
+}
+
+// TestReconcileOnce_RPCError_NoOrphan verifies that a transient RPC error
+// (getblockhash fails) does not cause a block to be orphaned. The next
+// reconcile sweep will retry.
+func TestReconcileOnce_RPCError_NoOrphan(t *testing.T) {
+	st := openTempStore(t)
+
+	st.InsertBlock(store.Block{
+		Height:   300,
+		Hash:     "our_hash_cccc",
+		RewardBT: 3.125,
+		FoundAt:  time.Now(),
+		Source:   "test",
+		Chain:    "main",
+	})
+
+	rpc := mockRPC(t, func(method string) (any, *rpcErrResp) {
+		if method == "getblockhash" {
+			return nil, &rpcErrResp{Code: -5, Message: "Block not found"}
+		}
+		return nil, nil
+	})
+
+	agg := newAgg(st, rpc)
+	setChain(agg, "main")
+
+	agg.reconcileOnce(context.Background())
+
+	blocks, _ := st.Recent(10)
+	for _, b := range blocks {
+		if b.Height == 300 && !b.OrphanedAt.IsZero() {
+			t.Error("block was orphaned on RPC error — should only orphan on definitive hash mismatch")
+		}
+	}
+}
+
+// TestReconcileOnce_LegacyBlock_StillChecked verifies that a legacy block
+// (Chain == "") is still checked for reorgs on the current chain, preserving
+// backward compatibility for installs that existed before chain was tracked.
+func TestReconcileOnce_LegacyBlock_StillChecked(t *testing.T) {
+	st := openTempStore(t)
+
+	st.InsertBlock(store.Block{
+		Height:   400,
+		Hash:     "legacy_hash",
+		RewardBT: 3.125,
+		FoundAt:  time.Now(),
+		Source:   "test",
+		Chain:    "", // legacy — no chain recorded
+	})
+
+	// Mainnet canonical hash differs: should orphan even though Chain is empty.
+	rpc := mockRPC(t, func(method string) (any, *rpcErrResp) {
+		if method == "getblockhash" {
+			return "different_canonical", nil
+		}
+		return nil, nil
+	})
+
+	agg := newAgg(st, rpc)
+	setChain(agg, "main")
+
+	agg.reconcileOnce(context.Background())
+
+	blocks, _ := st.Recent(10)
+	for _, b := range blocks {
+		if b.Height == 400 && b.OrphanedAt.IsZero() {
+			t.Error("legacy block (empty chain) should still be checked for reorgs")
+		}
+	}
+}
+
+// ---- IngestBlockEvents tests ----
+
+// TestIngestBlockEvents_NewBlock verifies that a fresh block event is
+// persisted to the store and the confirmed counter increments.
+func TestIngestBlockEvents_NewBlock(t *testing.T) {
+	st := openTempStore(t)
+	agg := newAgg(st, nil) // nil RPC skips enrichment
+	setChain(agg, "main")
+
+	events := make(chan logmon.BlockEvent, 1)
+
+	done := make(chan struct{})
+	agg.OnRefresh = func(_ Snapshot) { close(done) }
+
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+	defer cancel()
+	go agg.IngestBlockEvents(ctx, events)
+
+	events <- logmon.BlockEvent{Height: 500, SeenAt: time.Now(), ShareDiff: 32768}
+
+	select {
+	case <-done:
+	case <-ctx.Done():
+		t.Fatal("timed out waiting for block to be processed")
+	}
+
+	blocks, _ := st.Recent(10)
+	if len(blocks) == 0 {
+		t.Fatal("block not persisted to store")
+	}
+	if blocks[0].Height != 500 {
+		t.Errorf("Height = %d, want 500", blocks[0].Height)
+	}
+	if blocks[0].Chain != "main" {
+		t.Errorf("Chain = %q, want main", blocks[0].Chain)
+	}
+
+	agg.mu.RLock()
+	confirmed := agg.blockSubmitsConfirmed
+	agg.mu.RUnlock()
+	if confirmed != 1 {
+		t.Errorf("blockSubmitsConfirmed = %d, want 1", confirmed)
+	}
+}
+
+// TestIngestBlockEvents_Dedup verifies that sending the same block height
+// twice does not double-count the confirmed counter or call OnRefresh twice.
+func TestIngestBlockEvents_Dedup(t *testing.T) {
+	st := openTempStore(t)
+
+	// Pre-insert the block so the first ingest sees it as a duplicate.
+	st.InsertBlock(store.Block{Height: 600, FoundAt: time.Now(), Chain: "main"})
+
+	var refreshCount int
+	var mu sync.Mutex
+
+	agg := newAgg(st, nil)
+	agg.OnRefresh = func(_ Snapshot) {
+		mu.Lock()
+		refreshCount++
+		mu.Unlock()
+	}
+	setChain(agg, "main")
+
+	events := make(chan logmon.BlockEvent, 1)
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+	defer cancel()
+
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		agg.IngestBlockEvents(ctx, events)
+	}()
+
+	events <- logmon.BlockEvent{Height: 600, SeenAt: time.Now()}
+	close(events)
+	wg.Wait()
+
+	agg.mu.RLock()
+	confirmed := agg.blockSubmitsConfirmed
+	agg.mu.RUnlock()
+	if confirmed != 0 {
+		t.Errorf("blockSubmitsConfirmed = %d, want 0 for duplicate", confirmed)
+	}
+
+	mu.Lock()
+	rc := refreshCount
+	mu.Unlock()
+	if rc != 0 {
+		t.Errorf("OnRefresh called %d times, want 0 for duplicate block", rc)
+	}
+}
+
+// TestIngestBlockEvents_ChainStamping verifies that the block record stored
+// carries the chain name from the current snapshot at ingest time.
+func TestIngestBlockEvents_ChainStamping(t *testing.T) {
+	st := openTempStore(t)
+	agg := newAgg(st, nil)
+	setChain(agg, "test") // testnet at the time of the solve
+
+	events := make(chan logmon.BlockEvent, 1)
+	done := make(chan struct{})
+	agg.OnRefresh = func(_ Snapshot) { close(done) }
+
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+	defer cancel()
+	go agg.IngestBlockEvents(ctx, events)
+
+	events <- logmon.BlockEvent{Height: 700, SeenAt: time.Now()}
+
+	select {
+	case <-done:
+	case <-ctx.Done():
+		t.Fatal("timed out waiting for block to be processed")
+	}
+
+	blocks, _ := st.Recent(10)
+	if len(blocks) == 0 {
+		t.Fatal("block not found in store")
+	}
+	if blocks[0].Chain != "test" {
+		t.Errorf("Chain = %q, want test — chain stamping broken", blocks[0].Chain)
+	}
+}
diff --git a/api/internal/store/blocks_test.go b/api/internal/store/blocks_test.go
new file mode 100644
index 0000000..a2c15fa
--- /dev/null
+++ b/api/internal/store/blocks_test.go
@@ -0,0 +1,270 @@
+package store
+
+import (
+	"database/sql"
+	"os"
+	"testing"
+	"time"
+
+	_ "modernc.org/sqlite"
+)
+
+func openTemp(t *testing.T) *BlockStore {
+	t.Helper()
+	f, err := os.CreateTemp("", "kamado*.db")
+	if err != nil {
+		t.Fatal(err)
+	}
+	f.Close()
+	t.Cleanup(func() { _ = os.Remove(f.Name()) })
+
+	s, err := Open(f.Name())
+	if err != nil {
+		t.Fatalf("Open: %v", err)
+	}
+	t.Cleanup(func() { _ = s.Close() })
+	return s
+}
+
+func TestInsertBlock_Roundtrip(t *testing.T) {
+	s := openTemp(t)
+	now := time.Now().UTC().Truncate(time.Second)
+
+	b := Block{
+		Height:   840000,
+		Hash:     "000000000000000000024bead8df69990852c202db0e0097c1a12ea637d7e96d",
+		RewardBT: 3.125,
+		FoundAt:  now,
+		Source:   "logmon",
+		ShareDiff: 8_000_000,
+		Chain:    "main",
+	}
+	inserted, err := s.InsertBlock(b)
+	if err != nil {
+		t.Fatalf("InsertBlock: %v", err)
+	}
+	if !inserted {
+		t.Fatal("expected inserted=true for a new block")
+	}
+
+	blocks, err := s.Recent(10)
+	if err != nil {
+		t.Fatalf("Recent: %v", err)
+	}
+	if len(blocks) != 1 {
+		t.Fatalf("Recent returned %d blocks, want 1", len(blocks))
+	}
+	got := blocks[0]
+	if got.Height != b.Height {
+		t.Errorf("Height = %d, want %d", got.Height, b.Height)
+	}
+	if got.Hash != b.Hash {
+		t.Errorf("Hash = %q, want %q", got.Hash, b.Hash)
+	}
+	if got.RewardBT != b.RewardBT {
+		t.Errorf("RewardBT = %v, want %v", got.RewardBT, b.RewardBT)
+	}
+	if !got.FoundAt.Equal(b.FoundAt) {
+		t.Errorf("FoundAt = %v, want %v", got.FoundAt, b.FoundAt)
+	}
+	if got.Chain != "main" {
+		t.Errorf("Chain = %q, want \"main\"", got.Chain)
+	}
+	if !got.OrphanedAt.IsZero() {
+		t.Errorf("OrphanedAt should be zero, got %v", got.OrphanedAt)
+	}
+}
+
+func TestInsertBlock_Dedup(t *testing.T) {
+	s := openTemp(t)
+	b := Block{Height: 100, FoundAt: time.Now(), Chain: "main"}
+
+	inserted1, err := s.InsertBlock(b)
+	if err != nil || !inserted1 {
+		t.Fatalf("first insert: err=%v inserted=%v", err, inserted1)
+	}
+
+	inserted2, err := s.InsertBlock(b)
+	if err != nil {
+		t.Fatalf("second insert: %v", err)
+	}
+	if inserted2 {
+		t.Error("second insert at same height should return inserted=false")
+	}
+
+	blocks, _ := s.Recent(10)
+	if len(blocks) != 1 {
+		t.Errorf("store has %d blocks after dedup, want 1", len(blocks))
+	}
+}
+
+func TestMarkOrphaned_RoundTrip(t *testing.T) {
+	s := openTemp(t)
+	b := Block{Height: 200, Hash: "abc123", FoundAt: time.Now(), Chain: "main"}
+	s.InsertBlock(b)
+
+	orphanTime := time.Now().UTC().Truncate(time.Second)
+	if err := s.MarkOrphaned(200, orphanTime); err != nil {
+		t.Fatalf("MarkOrphaned: %v", err)
+	}
+
+	blocks, _ := s.Recent(10)
+	if len(blocks) == 0 {
+		t.Fatal("no blocks after MarkOrphaned")
+	}
+	if blocks[0].OrphanedAt.IsZero() {
+		t.Error("OrphanedAt should be set after MarkOrphaned")
+	}
+	if !blocks[0].OrphanedAt.Equal(orphanTime) {
+		t.Errorf("OrphanedAt = %v, want %v", blocks[0].OrphanedAt, orphanTime)
+	}
+}
+
+func TestUpdateEnrichment(t *testing.T) {
+	s := openTemp(t)
+	s.InsertBlock(Block{Height: 300, FoundAt: time.Now(), Chain: "main"})
+
+	if err := s.UpdateEnrichment(300, "newhash", 3.125); err != nil {
+		t.Fatalf("UpdateEnrichment: %v", err)
+	}
+
+	blocks, _ := s.Recent(10)
+	if blocks[0].Hash != "newhash" {
+		t.Errorf("Hash = %q, want newhash", blocks[0].Hash)
+	}
+	if blocks[0].RewardBT != 3.125 {
+		t.Errorf("RewardBT = %v, want 3.125", blocks[0].RewardBT)
+	}
+}
+
+func TestBlocksNeedingEnrichment(t *testing.T) {
+	s := openTemp(t)
+	now := time.Now()
+
+	// Block missing hash → needs enrichment.
+	s.InsertBlock(Block{Height: 1, FoundAt: now, Chain: "main"})
+	// Block with hash but no reward → needs enrichment.
+	s.InsertBlock(Block{Height: 2, Hash: "abc", RewardBT: 0, FoundAt: now, Chain: "main"})
+	// Block fully enriched → does NOT need enrichment.
+	s.InsertBlock(Block{Height: 3, Hash: "def", RewardBT: 3.125, FoundAt: now, Chain: "main"})
+
+	since := now.Add(-time.Hour)
+	missing, err := s.BlocksNeedingEnrichment(since)
+	if err != nil {
+		t.Fatalf("BlocksNeedingEnrichment: %v", err)
+	}
+	if len(missing) != 2 {
+		t.Errorf("got %d blocks needing enrichment, want 2", len(missing))
+	}
+	for _, b := range missing {
+		if b.Height == 3 {
+			t.Error("fully enriched block should not appear in missing list")
+		}
+	}
+}
+
+// TestMigrate_AddsChainColumn creates a database with the old schema
+// (no chain column) and verifies Open() migrates it transparently.
+func TestMigrate_AddsChainColumn(t *testing.T) {
+	f, err := os.CreateTemp("", "kamado_old*.db")
+	if err != nil {
+		t.Fatal(err)
+	}
+	f.Close()
+	t.Cleanup(func() { _ = os.Remove(f.Name()) })
+
+	// Build old-style schema without the chain column.
+	db, err := sql.Open("sqlite", f.Name())
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, err = db.Exec(`CREATE TABLE blocks (
+		height       INTEGER PRIMARY KEY,
+		hash         TEXT NOT NULL DEFAULT '',
+		reward_btc   REAL NOT NULL DEFAULT 0,
+		found_at     INTEGER NOT NULL,
+		source       TEXT NOT NULL DEFAULT '',
+		share_diff   REAL NOT NULL DEFAULT 0,
+		orphaned_at  INTEGER NOT NULL DEFAULT 0
+	)`)
+	if err != nil {
+		db.Close()
+		t.Fatalf("create old schema: %v", err)
+	}
+	_, err = db.Exec(`INSERT INTO blocks(height, found_at) VALUES (999, ?)`, time.Now().Unix())
+	if err != nil {
+		db.Close()
+		t.Fatalf("insert old row: %v", err)
+	}
+	db.Close()
+
+	// Open via our store — migrate() must add the chain column.
+	s, err := Open(f.Name())
+	if err != nil {
+		t.Fatalf("Open after migration: %v", err)
+	}
+	defer s.Close()
+
+	// Insert a block with a chain value — would fail if migration didn't add
+	// the column.
+	inserted, err := s.InsertBlock(Block{
+		Height:  1000,
+		FoundAt: time.Now(),
+		Chain:   "test",
+	})
+	if err != nil {
+		t.Fatalf("InsertBlock after migration: %v", err)
+	}
+	if !inserted {
+		t.Error("expected inserted=true")
+	}
+
+	blocks, err := s.Recent(10)
+	if err != nil {
+		t.Fatalf("Recent: %v", err)
+	}
+	// Row 999 (old, no chain) and row 1000 (new, chain="test").
+	if len(blocks) != 2 {
+		t.Fatalf("got %d blocks, want 2", len(blocks))
+	}
+	// Newest first; row 1000 is first.
+	if blocks[0].Chain != "test" {
+		t.Errorf("new block chain = %q, want test", blocks[0].Chain)
+	}
+	if blocks[1].Chain != "" {
+		t.Errorf("old block chain = %q, want \"\" (empty default)", blocks[1].Chain)
+	}
+}
+
+func TestKVRoundTrip(t *testing.T) {
+	s := openTemp(t)
+
+	if err := s.SetKV("foo", "bar"); err != nil {
+		t.Fatalf("SetKV: %v", err)
+	}
+	v, err := s.GetKV("foo")
+	if err != nil {
+		t.Fatalf("GetKV: %v", err)
+	}
+	if v != "bar" {
+		t.Errorf("GetKV = %q, want bar", v)
+	}
+
+	// Overwrite.
+	if err := s.SetKV("foo", "baz"); err != nil {
+		t.Fatalf("SetKV overwrite: %v", err)
+	}
+	v2, _ := s.GetKV("foo")
+	if v2 != "baz" {
+		t.Errorf("after overwrite GetKV = %q, want baz", v2)
+	}
+
+	// Missing key returns empty string.
+	v3, err := s.GetKV("nonexistent")
+	if err != nil {
+		t.Fatalf("GetKV missing: %v", err)
+	}
+	if v3 != "" {
+		t.Errorf("missing key GetKV = %q, want empty", v3)
+	}
+}