monitor: commit the running supervisor, which existed only in memory

/home/dev/lightwalletd/monitor_lwd.sh was carrying two uncommitted
production fixes, and the copy on disk had been reverted to the broken
committed version. The monitor that is actually running was executing a
deleted inode, so the fixes survived only as long as that process did --
any restart would have picked up the broken file.

The two fixes that were nearly lost:

  * `-cache-size 5000` on the launch line. Without it a relaunch warms
    the block cache from tip-400000 instead of tip-5000, which is
    several minutes of getblock storm against the local node and several
    minutes during which every wallet errors "Server's latest block is
    behind ours".

  * `EXIT_CODE=0; wait "$LWD_PID" || EXIT_CODE=$?` instead of
    `wait "$LWD_PID" || true; EXIT_CODE=$?`. The latter reads the status
    of `|| true` and is therefore always 0, so the monitor logged
    "exited cleanly. Not restarting." and broke its loop on every exit
    including crashes. That bug produced an 11h48m outage on 2026-08-21.

Recovered byte-identical from the running monitor via /proc/<pid>/fd/255
(md5 1823440d0af509c92583796af075b657) and committed so a checkout
cannot discard it again. An out-of-repo copy is kept at
/home/dev/monitor_lwd.sh.good.

Note the other branches still carry the broken blob; checking one out in
this working tree will clobber this file again. This working tree is a
live operational directory, not just a source checkout.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FU87LdsJZiZkfq1eXubpeo

cmd/server/main.go

@@ -93,7 +93,7 @@ type Options struct {
 }
 
 func main() {
-	var version = "0.1.1" // set version number
+	var version = common.Version
 
 	opts := &Options{}
 	flag.StringVar(&opts.bindAddr, "bind-addr", "127.0.0.1:9069", "the address to listen on")

common/common.go

@@ -38,25 +38,32 @@ func GetSaplingInfo(rpcClient *rpcclient.Client) (int, int, string, string, int,
 		return -1, -1, "", "", -1, -1, -1, errors.Wrap(err, "error reading JSON response")
 	}
 
-	chainName := f.(map[string]interface{})["chain"].(string)
+	// Assert the top-level object once, then read every field with the comma-ok
+	// form. These run on the block-ingestor goroutine, and nothing in this
+	// daemon or in grpc-go v1.24.0 recovers a panic, so one unexpected response
+	// shape would take the whole process down rather than fail one call.
+	fmap, ok := f.(map[string]interface{})
+	if !ok {
+		return -1, -1, "", "", -1, -1, -1, errors.New("getblockchaininfo: unexpected response shape")
+	}
+	chainName, _ := fmap["chain"].(string)
 
 	// DragonX has Sapling active from block 1 but sets NO_ACTIVATION_HEIGHT in
 	// chainparams, so dragonxd omits it from the upgrades map. Fall back to
 	// height 1 when the key is absent.
 	saplingHeight := float64(1)
-	upgradeJSON, ok := f.(map[string]interface{})["upgrades"]
+	if upgradesMap, ok := fmap["upgrades"].(map[string]interface{}); ok {
-	if ok {
+		if saplingJSON, ok := upgradesMap["76b809bb"].(map[string]interface{}); ok {
-		if upgradesMap, ok := upgradeJSON.(map[string]interface{}); ok {
+			if h, ok := saplingJSON["activationheight"].(float64); ok {
-			if saplingJSON, ok := upgradesMap["76b809bb"]; ok {
+				saplingHeight = h
-				saplingHeight = saplingJSON.(map[string]interface{})["activationheight"].(float64)
 			}
 		}
 	}
 
-	blockHeight := f.(map[string]interface{})["headers"].(float64)
+	blockHeight, _ := fmap["headers"].(float64)
-	difficulty := f.(map[string]interface{})["difficulty"].(float64)
+	difficulty, _ := fmap["difficulty"].(float64)
-	longestchain := f.(map[string]interface{})["longestchain"].(float64)
+	longestchain, _ := fmap["longestchain"].(float64)
-	notarized := f.(map[string]interface{})["notarized"].(float64)
+	notarized, _ := fmap["notarized"].(float64)
 
 	// DragonX always uses Sapling consensus rules but CurrentEpochBranchId()
 	// returns Sprout (0) for full nodes because the activation heights are

common/version.go

@@ -0,0 +1,14 @@
+package common
+
+// Version is the single source of truth for this daemon's version.
+//
+// It was previously duplicated as a literal in two places that could drift:
+// cmd/server/main.go's --version output and the Version field of the LightdInfo
+// gRPC reply in frontend/service.go. The gRPC one is the load-bearing copy --
+// it is walletrpc/service.proto:48, so every client and every operator probe
+// reads it, and it is the only way to tell from off-box which build a node is
+// running.
+const Version = "0.1.2"
+
+// VersionString is what GetLightdInfo advertises to clients.
+const VersionString = Version + "-dragonxlightd"

frontend/service.go

@@ -293,7 +293,26 @@ func (s *SqlStreamer) GetTransaction(ctx context.Context, txf *walletrpc.TxFilte
 		if err != nil {
 			return nil, err
 		}
-		txHeight = txinfo.(map[string]interface{})["height"].(float64)
+		// dragonxd emits "height" only for a transaction that is in a block:
+		// rawtransaction.cpp puts it inside `if (!hashBlock.IsNull())`. Every
+		// mempool transaction therefore comes back WITHOUT the key, and an
+		// unchecked assertion on the missing value panics -- which, with no
+		// recover() anywhere in grpc-go v1.24.0 or in this daemon, kills the
+		// whole process and every wallet connected to it. Any client can reach
+		// this by broadcasting a transaction and immediately asking for it, and
+		// GetMempoolStream hands out unconfirmed txids by design.
+		//
+		// Report an unconfirmed transaction as tip+1, matching what
+		// GetMempoolStream already advertises (mempool.go:109).
+		txmap, ok := txinfo.(map[string]interface{})
+		if !ok {
+			return nil, errors.New("getrawtransaction: unexpected response shape")
+		}
+		if h, ok := txmap["height"].(float64); ok {
+			txHeight = h
+		} else {
+			txHeight = float64(s.cache.GetLatestBlock() + 1)
+		}
 
 		return &walletrpc.RawTransaction{Data: txBytes, Height: uint64(txHeight)}, nil
 	}
@@ -334,7 +353,7 @@ func (s *SqlStreamer) GetLightdInfo(ctx context.Context, in *walletrpc.Empty) (*
 	// TODO these are called Error but they aren't at the moment.
 	// A success will return code 0 and message txhash.
 	return &walletrpc.LightdInfo{
-		Version:                 "0.1.1-dragonxlightd",
+		Version:                 common.VersionString,
 		Vendor:                  "DragonX LightWalletD",
 		TaddrSupport:            true,
 		ChainName:               chainName,

monitor_lwd.sh

@@ -10,9 +10,10 @@ set -euo pipefail
 
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
 LWD_BIN="$SCRIPT_DIR/lightwalletd"
-LWD_ARGS="-bind-addr lite.dragonx.is:9069 -conf-file $HOME/.hush/DRAGONX/DRAGONX.conf -no-tls -lag-min 4 -lag-max 12 -lag-window 30"
+LWD_ARGS="-bind-addr lite.dragonx.is:9069 -conf-file $HOME/.hush/DRAGONX/DRAGONX.conf -no-tls -lag-min 4 -lag-max 12 -lag-window 30 -cache-size 5000"
 LOGFILE="$SCRIPT_DIR/lwd-monitor.log"
 PIDFILE="/tmp/lwd-monitor.pid"
+STOPPING=0
 RESTART_DELAY=5        # seconds to wait before restarting after a crash
 MAX_RAPID_RESTARTS=5   # max restarts within the rapid window before backing off
 RAPID_WINDOW=120       # seconds — if this many restarts happen within this window, back off
@@ -29,6 +30,7 @@ log() {
 }
 
 cleanup() {
+    STOPPING=1
     log "${YELLOW}Monitor shutting down...${NC}"
     if [[ -n "${LWD_PID:-}" ]] && kill -0 "$LWD_PID" 2>/dev/null; then
         log "Stopping lightwalletd (PID $LWD_PID)..."
@@ -75,6 +77,7 @@ log "Args:    $LWD_ARGS"
 
 restart_times=()
 LWD_PID=""
+STOPPING=0
 
 while true; do
     # Start lightwalletd
@@ -84,12 +87,12 @@ while true; do
     log "lightwalletd started with PID $LWD_PID"
 
     # Wait for it to exit
-    wait "$LWD_PID" || true
+    EXIT_CODE=0
-    EXIT_CODE=$?
+    wait "$LWD_PID" || EXIT_CODE=$?
     LWD_PID=""
 
-    if [[ $EXIT_CODE -eq 0 ]]; then
+    if [[ $STOPPING -eq 1 ]]; then
-        log "${YELLOW}lightwalletd exited cleanly (code 0). Not restarting.${NC}"
+        log "${YELLOW}lightwalletd stopped on request (code $EXIT_CODE). Not restarting.${NC}"
         break
     fi