bwatch: gate chain polling behind --experimental-bwatch

diff --git a/doc/lightningd-config.5.md b/doc/lightningd-config.5.md
index 847a0757..d3a98b1c 100644
--- a/doc/lightningd-config.5.md
+++ b/doc/lightningd-config.5.md
@@ -583,6 +583,11 @@ command, so they invoices can also be paid onchain.
 
   Delay between polls for new blocks from `bitcoind` (default: 30000).
 
+* **experimental-bwatch** [plugin `bwatch`]
+
+  Enable the experimental *bwatch* chain watcher.  Without this, the
+  plugin stays loaded but does not poll `bitcoind` or process watches.
+
 ### Networking options
 
 Note that for simple setups, the implicit *autolisten* option does the
diff --git a/plugins/bwatch/bwatch.c b/plugins/bwatch/bwatch.c
index 4e548608..da373a6f 100644
--- a/plugins/bwatch/bwatch.c
+++ b/plugins/bwatch/bwatch.c
@@ -448,6 +448,16 @@ static const char *init(struct command *cmd,
 
 	bwatch->block_history = tal_arr(bwatch, struct block_record_wire, 0);
 
+	/* Default to "no chain seen yet"; bwatch_load_block_history will
+	 * overwrite these from the datastore when we're enabled. */
+	bwatch->current_height = 0;
+	memset(&bwatch->current_blockhash, 0, sizeof(bwatch->current_blockhash));
+
+	/* bwatch is opt-in: leave the plugin loaded but skip chain polling until the
+	 * user passes --experimental-bwatch. */
+	if (!bwatch->experimental)
+		return NULL;
+
 	/* Replay persisted block history.  load_block_history sets
 	 * current_height / current_blockhash from the most recent record;
 	 * if there are no records, fall back to zero so the first poll
@@ -481,12 +491,18 @@ int main(int argc, char *argv[])
 	setup_locale();
 	bwatch = tal(NULL, struct bwatch);
 	bwatch->poll_interval_ms = 30000;
+	bwatch->experimental = false;
 
 	plugin_main(argv, init, take(bwatch), PLUGIN_RESTARTABLE, true, NULL,
 		    commands, ARRAY_SIZE(commands),
 		    NULL, 0,
 		    NULL, 0,
 		    NULL, 0,
+		    plugin_option("experimental-bwatch", "flag",
+				  "experimental: enable the bwatch chain"
+				  " watcher (off by default)",
+				  flag_option, flag_jsonfmt,
+				  &bwatch->experimental),
 		    plugin_option("bwatch-poll-interval", "int",
 				  "Milliseconds between chain polls (default: 30000)",
 				  u32_option, u32_jsonfmt, &bwatch->poll_interval_ms),
diff --git a/plugins/bwatch/bwatch.h b/plugins/bwatch/bwatch.h
index ab60286a..3fe886b0 100644
--- a/plugins/bwatch/bwatch.h
+++ b/plugins/bwatch/bwatch.h
@@ -70,6 +70,10 @@ struct bwatch {
 	/* Active poll timer; rescheduled at the end of every poll cycle. */
 	struct plugin_timer *poll_timer;
 	u32 poll_interval_ms;
+
+	/* Opt-in: bwatch is loaded but stays inert (no chain polling, no
+	 * watch processing) unless the user passes --experimental-bwatch. */
+	bool experimental;
 };
 
 /* Helper: get last block_history (or NULL) */
diff --git a/tests/test_plugin.py b/tests/test_plugin.py
index 679b8e0b..e224e363 100644
--- a/tests/test_plugin.py
+++ b/tests/test_plugin.py
@@ -32,8 +32,8 @@ import sys
 import time
 import unittest
 
-# Fast bwatch polling for tests (plugin default is 30s). Pass explicitly per node.
-BWATCH_OPTS = {'bwatch-poll-interval': 500}
+# bwatch is opt-in (--experimental-bwatch); also speed up polling for tests.
+BWATCH_OPTS = {'experimental-bwatch': None, 'bwatch-poll-interval': 500}
 
 
 def wait_bwatch_caught_up(node, timeout=TIMEOUT):