diff --git a/config.example.json b/config.example.json
index 64bd00c0..5d7ff0f9 100644
--- a/config.example.json
+++ b/config.example.json
@@ -224,8 +224,8 @@
     "_comment_observerThresholds": "Observer health classification. Online: last_seen < observerOnlineMinutes ago. Stale: between Online and observerStaleMinutes. Offline: beyond observerStaleMinutes. Defaults 60 / 1440 (1h / 24h) match the node thresholds for consistency and eliminate flap on low-traffic / CDN-fronted instances (#1552). Operators who want the old aggressive 10-min Online threshold can set observerOnlineMinutes: 10."
   },
   "pathTrust": {
-    "minHashBytesForMapping": 2,
-    "_comment_pathTrust": "Minimum path-hash prefix length, in bytes, trusted as mapping/topology evidence (issue #1784). MeshCore path hops are hashed pubkey prefixes of 1, 2, or 3 bytes (firmware hash_size = (pathByte>>6)+1); valid range is 1-3. Default 2 excludes 1-byte prefixes (256-value collision space) from mapping evidence — operator-confirmed to reduce false positives on denser meshes. Set to 1 for backward-compatible trust-all behavior. Set to 3 for the strictest mode (only 3-byte evidence trusted). This does not affect raw storage — packets/paths are always stored as received."
+    "minHashBytesForMapping": 1,
+    "_comment_pathTrust": "Minimum path-hash prefix length, in bytes, trusted as mapping/topology evidence (issue #1784). MeshCore path hops are hashed pubkey prefixes of 1, 2 or 3 bytes (firmware hash_size = (pathByte>>6)+1); valid range is 1-3. Default 1 keeps the pre-#1784 behaviour, where every prefix length counts. Set 2 to exclude 1-byte prefixes (256-value collision space, so a currently-unique match can still be a false positive on a dense mesh), or 3 to require the strongest evidence. NOTE: there is no UI control for this - it is config-only and needs a restart, and raising it can remove a large share of your neighbour-graph edges and resolved paths with nothing in the UI explaining why. This does not affect raw storage: packets and paths are always stored as received."
   },
   "defaultRegion": "SJC",
   "mapDefaults": {
diff --git a/internal/packetpath/trust.go b/internal/packetpath/trust.go
index 06daa3e0..b33f1eb2 100644
--- a/internal/packetpath/trust.go
+++ b/internal/packetpath/trust.go
@@ -20,7 +20,19 @@ type TrustConfig struct {
 	MinHashBytesForMapping int `json:"minHashBytesForMapping,omitempty"`
 }
 
-const DefaultMinHashBytesForMapping = 2
+// DefaultMinHashBytesForMapping is the backward-compatible default: every
+// prefix length counts as mapping evidence, exactly as before #1784.
+//
+// It is deliberately 1 rather than the stricter 2. There is no UI control for
+// this threshold, it can only be changed in config.json and that needs a
+// restart, so shipping 2 would tighten every instance on upgrade with nothing
+// in the UI explaining why the neighbour graph shrank. Measured on a live
+// network, 56% of path-hop observations carry a 1-byte prefix and 41% of
+// repeaters use a 1-byte hash, so that is not a marginal change. Issue #1784's
+// own first acceptance criterion is that the default stays backward compatible.
+//
+// Operators who want the stricter behaviour set minHashBytesForMapping: 2 or 3.
+const DefaultMinHashBytesForMapping = 1
 
 const MaxHashBytes = 3
 
diff --git a/internal/packetpath/trust_test.go b/internal/packetpath/trust_test.go
index 08f3a0cb..4462b354 100644
--- a/internal/packetpath/trust_test.go
+++ b/internal/packetpath/trust_test.go
@@ -3,13 +3,16 @@ package packetpath
 import "testing"
 
 func TestMeetsPathTrust_DefaultThreshold(t *testing.T) {
-	// nil cfg → DefaultMinHashBytesForMapping (2): 0-byte and 1-byte excluded.
+	// nil cfg → DefaultMinHashBytesForMapping (1): everything is trusted, which
+	// is the pre-#1784 behaviour. This test is the guard on that promise: if the
+	// default is ever raised, upgrading instances silently lose a large share of
+	// their mapping evidence with no UI control to opt back out.
 	cases := []struct {
 		prefixBytes int
 		want        bool
 	}{
-		{0, false},
-		{1, false},
+		{0, true},
+		{1, true},
 		{2, true},
 		{3, true},
 	}
@@ -49,17 +52,25 @@ func TestMeetsPathTrust_Exclude1Byte(t *testing.T) {
 }
 
 func TestMeetsPathTrust_ZeroValueOptIn(t *testing.T) {
-	// A zero-value MinHashBytesForMapping (unset) must fall back to default (2),
-	// so bucket-0 and 1-byte prefixes fail; 2-byte and above pass.
-	cfg := &TrustConfig{}
-	if MeetsPathTrust(1, cfg) {
-		t.Errorf("MeetsPathTrust(1, %+v) = true, want false (unset uses default=2, 1-byte excluded)", cfg)
+	// A zero-value MinHashBytesForMapping (the JSON field absent) must resolve to
+	// DefaultMinHashBytesForMapping, not be read as an explicit opt-in to some
+	// other number. Asserted against the constant rather than against a literal
+	// so this keeps testing the property if the default is ever changed again.
+	unset := &TrustConfig{}
+	if got := unset.MinHashBytesOrDefault(); got != DefaultMinHashBytesForMapping {
+		t.Errorf("unset.MinHashBytesOrDefault() = %d, want %d", got, DefaultMinHashBytesForMapping)
 	}
-	if MeetsPathTrust(0, cfg) {
-		t.Errorf("MeetsPathTrust(0, %+v) = true, want false (bucket-0 excluded at default threshold)", cfg)
+	// And it must behave identically to a config that names the default outright.
+	explicit := &TrustConfig{MinHashBytesForMapping: DefaultMinHashBytesForMapping}
+	for _, prefixBytes := range []int{0, 1, 2, 3} {
+		if MeetsPathTrust(prefixBytes, unset) != MeetsPathTrust(prefixBytes, explicit) {
+			t.Errorf("prefixBytes=%d: unset and explicit-default disagree", prefixBytes)
+		}
 	}
-	if !MeetsPathTrust(2, cfg) {
-		t.Errorf("MeetsPathTrust(2, %+v) = false, want true (2-byte passes at default threshold)", cfg)
+	// An explicit stricter setting must still be honoured over the default.
+	strict := &TrustConfig{MinHashBytesForMapping: 2}
+	if MeetsPathTrust(1, strict) {
+		t.Error("MeetsPathTrust(1, minBytes=2) = true, want false — an explicit setting must win")
 	}
 }
 
diff --git a/public/customize-v2.js b/public/customize-v2.js
index 7c9c1ea1..68fb33e6 100644
--- a/public/customize-v2.js
+++ b/public/customize-v2.js
@@ -1604,7 +1604,7 @@
     try { on = localStorage.getItem('meshcore-hide-1byte-hops') === 'true'; } catch (_e) {}
     var trustThreshold = (typeof window.MC_getPathTrustThreshold === 'function')
       ? window.MC_getPathTrustThreshold()
-      : 2;
+      : 1;
     var trustDesc = trustThreshold >= 2
       ? '1-byte path-hash prefixes collide ~8-way at ~2k relays and are excluded from topology/mapping evidence (minHashBytesForMapping: ' + trustThreshold + '). Routes below this threshold show as speculative or are excluded. Change via pathTrust.minHashBytesForMapping in config.json.'
       : '1-byte path-hash prefixes collide ~8-way at ~2k relays — many polylines and rows they produce are visual noise. Hide them here without changing what\'s stored. Set pathTrust.minHashBytesForMapping in config.json to 2 or 3 for stricter server-side evidence requirements.';
diff --git a/public/hop-filter.js b/public/hop-filter.js
index 73c283fa..c2ccac3e 100644
--- a/public/hop-filter.js
+++ b/public/hop-filter.js
@@ -56,7 +56,7 @@
     if (typeof window !== 'undefined' && typeof window.PATH_TRUST === 'number') {
       return window.PATH_TRUST;
     }
-    return 2;
+    return 1;
   }
 
   // #1784 — whether a hop meets the server-side path trust threshold.
diff --git a/test-issue-1633-hide-1byte-hops.js b/test-issue-1633-hide-1byte-hops.js
index b7754b5c..74068890 100644
--- a/test-issue-1633-hide-1byte-hops.js
+++ b/test-issue-1633-hide-1byte-hops.js
@@ -451,12 +451,18 @@ test('[kb #1] anti-tautology: tests reference the actual production files (not i
 
 console.log('\n=== #1784: path trust threshold ===');
 
-test('#1784: MC_getPathTrustThreshold default is 2 (operator-confirmed)', () => {
+test('#1784: MC_getPathTrustThreshold defaults to 1 (backward compatible)', () => {
+  // Deliberately 1, matching DefaultMinHashBytesForMapping in
+  // internal/packetpath/trust.go. There is no UI control for this threshold —
+  // it is config.json only and needs a restart — so a stricter default would
+  // silently tighten every instance on upgrade with nothing in the UI saying
+  // why the neighbour graph shrank. Operators opt in with
+  // pathTrust.minHashBytesForMapping: 2 or 3.
   const ctx = makeSandbox();
   load(ctx, 'public/hop-filter.js');
   delete ctx.window.PATH_TRUST;
-  assert.strictEqual(ctx.window.MC_getPathTrustThreshold(), 2,
-    'default path trust threshold must be 2 (operator-confirmed, excludes 1-byte)');
+  assert.strictEqual(ctx.window.MC_getPathTrustThreshold(), 1,
+    'default path trust threshold must be 1 so an upgrade changes nothing');
 });
 
 test('#1784: MC_getPathTrustThreshold reads window.PATH_TRUST', () => {