fix(channels): strip leading hash prefixes from names (#2250)

Signed-off-by: Logan Johnson <loganj@squareup.com>
Signed-off-by: npub1z3hmzc9ryehxzedl5wzlvpyvja0d483peaja5zt6pd0209f9x2jspe2dxh <146fb160a3266e6165bfa385f6048c975eda9e21cf65da097a0b5ea7952532a5@buzz.block.builderlab.xyz>
Signed-off-by: npub13n66s06epmqf2kc3v373ez8hj65cuzyvxzjf93vwpervxqn2u7jq2qd9je <8cf5a83f590ec0955b11647d1c88f796a98e088c30a492c58e0e46c3026ae7a4@buzz.block.builderlab.xyz>
Co-authored-by: npub1z3hmzc9ryehxzedl5wzlvpyvja0d483peaja5zt6pd0209f9x2jspe2dxh <146fb160a3266e6165bfa385f6048c975eda9e21cf65da097a0b5ea7952532a5@buzz.block.builderlab.xyz>
Co-authored-by: npub13n66s06epmqf2kc3v373ez8hj65cuzyvxzjf93vwpervxqn2u7jq2qd9je <8cf5a83f590ec0955b11647d1c88f796a98e088c30a492c58e0e46c3026ae7a4@buzz.block.builderlab.xyz>

crates/buzz-core/src/channel.rs

@@ -7,6 +7,16 @@
 use std::fmt;
 use std::str::FromStr;
 
+/// Returns the canonical display name for a channel.
+///
+/// Channel names are rendered with a leading `#` by clients, so surrounding
+/// whitespace and user-supplied hash prefixes are removed here to keep the
+/// stored name prefix-free.
+pub fn canonical_channel_name(name: &str) -> &str {
+    name.trim_start_matches(|c: char| c == '#' || c.is_whitespace())
+        .trim_end()
+}
+
 /// Whether a channel is publicly visible or invite-only.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum ChannelVisibility {
@@ -167,3 +177,22 @@ impl FromStr for MemberRole {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::canonical_channel_name;
+
+    #[test]
+    fn channel_names_trim_whitespace_and_drop_all_leading_hashes() {
+        assert_eq!(canonical_channel_name("channel"), "channel");
+        assert_eq!(canonical_channel_name("#channel"), "channel");
+        assert_eq!(canonical_channel_name("###channel"), "channel");
+        assert_eq!(canonical_channel_name("  ###channel  "), "channel");
+        assert_eq!(canonical_channel_name("# channel"), "channel");
+        assert_eq!(canonical_channel_name("### channel  "), "channel");
+        assert_eq!(canonical_channel_name("  ###  "), "");
+        assert_eq!(canonical_channel_name("# #"), "");
+        assert_eq!(canonical_channel_name("### ###"), "");
+        assert_eq!(canonical_channel_name("channel#topic"), "channel#topic");
+    }
+}

crates/buzz-db/src/channel.rs

@@ -101,6 +101,11 @@ pub async fn create_channel(
         )));
     }
 
+    let name = buzz_core::channel::canonical_channel_name(name);
+    if name.trim().is_empty() {
+        return Err(DbError::InvalidData("channel name is required".into()));
+    }
+
     let id = Uuid::new_v4();
 
     let mut tx = pool.begin().await?;
@@ -191,6 +196,11 @@ pub async fn create_channel_with_id(
         ));
     }
 
+    let name = buzz_core::channel::canonical_channel_name(name);
+    if name.trim().is_empty() {
+        return Err(DbError::InvalidData("channel name is required".into()));
+    }
+
     let mut tx = pool.begin().await?;
 
     let rows_affected = sqlx::query(
@@ -1041,7 +1051,7 @@ pub async fn update_channel(
     pool: &PgPool,
     community_id: CommunityId,
     channel_id: Uuid,
-    updates: ChannelUpdate,
+    mut updates: ChannelUpdate,
 ) -> Result<ChannelRecord> {
     if updates.name.is_none()
         && updates.description.is_none()
@@ -1053,6 +1063,13 @@ pub async fn update_channel(
         ));
     }
 
+    if let Some(name) = updates.name.as_mut() {
+        *name = buzz_core::channel::canonical_channel_name(name).to_owned();
+        if name.is_empty() {
+            return Err(DbError::InvalidData("channel name is required".into()));
+        }
+    }
+
     // Build SET clause dynamically — only include fields that are provided.
     // Track parameter index for positional placeholders.
     let mut set_parts: Vec<String> = Vec::new();

crates/buzz-relay/src/handlers/ingest.rs

@@ -2039,7 +2039,11 @@ async fn ingest_event_inner(
         });
         if create_name
             .as_ref()
-            .map(|n| n.trim().is_empty())
+            .map(|n| {
+                buzz_core::channel::canonical_channel_name(n)
+                    .trim()
+                    .is_empty()
+            })
             .unwrap_or(true)
         {
             return Err(IngestError::Rejected(
@@ -2082,6 +2086,7 @@ async fn ingest_event_inner(
 
         if let Some(client_uuid) = channel_id {
             let name = create_name.unwrap_or_default();
+            let name = buzz_core::channel::canonical_channel_name(&name);
 
             let description = event.tags.iter().find_map(|t| {
                 if t.kind().to_string() == "about" {
@@ -2099,7 +2104,7 @@ async fn ingest_event_inner(
                 .create_channel_with_id(
                     tenant.community(),
                     client_uuid,
-                    &name,
+                    name,
                     channel_type,
                     visibility,
                     description.as_deref(),

crates/buzz-relay/src/handlers/side_effects.rs

@@ -445,6 +445,22 @@ pub async fn validate_admin_event(
                 }
             }
 
+            // Validate channel names before storage. A name made entirely of
+            // display-prefix hashes becomes empty after canonicalization.
+            for t in event.tags.iter() {
+                if t.kind().to_string() == "name" {
+                    match t.content() {
+                        Some(v)
+                            if !buzz_core::channel::canonical_channel_name(v)
+                                .trim()
+                                .is_empty() => {}
+                        _ => {
+                            return Err(anyhow::anyhow!("channel name is required"));
+                        }
+                    }
+                }
+            }
+
             // Validate visibility values before storage.
             for t in event.tags.iter() {
                 if t.kind().to_string() == "visibility" {

crates/buzz-sdk/src/builders.rs

@@ -620,9 +620,18 @@ pub fn build_update_channel(
             ));
         }
     }
+    if name
+        .map(buzz_core::channel::canonical_channel_name)
+        .is_some_and(|name| name.trim().is_empty())
+    {
+        return Err(SdkError::InvalidTag("channel name is required".into()));
+    }
     let mut tags = vec![tag(&["h", &channel_id.to_string()])?];
     if let Some(n) = name {
-        tags.push(tag(&["name", n])?);
+        tags.push(tag(&[
+            "name",
+            buzz_core::channel::canonical_channel_name(n),
+        ])?);
     }
     if let Some(a) = about {
         tags.push(tag(&["about", a])?);
@@ -670,6 +679,10 @@ pub fn build_create_channel(
     about: Option<&str>,
     ttl: Option<i32>,
 ) -> Result<EventBuilder, SdkError> {
+    let name = buzz_core::channel::canonical_channel_name(name);
+    if name.trim().is_empty() {
+        return Err(SdkError::InvalidTag("channel name is required".into()));
+    }
     let mut tags = vec![tag(&["h", &channel_id.to_string()])?, tag(&["name", name])?];
     if let Some(v) = visibility {
         tags.push(tag(&["visibility", v.as_str()])?);
@@ -2381,6 +2394,21 @@ mod tests {
         assert!(has_tag(&ev, "about", "new about"));
     }
 
+    #[test]
+    fn update_channel_strips_all_leading_hashes_from_name() {
+        let ev =
+            sign(build_update_channel(uuid(), Some("  ###new-name  "), None, None, None).unwrap());
+        assert!(has_tag(&ev, "name", "new-name"));
+    }
+
+    #[test]
+    fn update_channel_rejects_hash_only_name() {
+        assert!(matches!(
+            build_update_channel(uuid(), Some("  ###  "), None, None, None),
+            Err(SdkError::InvalidTag(_))
+        ));
+    }
+
     #[test]
     fn update_channel_visibility_and_ttl() {
         let cid = uuid();
@@ -2471,6 +2499,37 @@ mod tests {
         assert!(has_tag(&ev, "name", "dev"));
     }
 
+    #[test]
+    fn create_channel_strips_all_leading_hashes_from_name() {
+        let ev = sign(
+            build_create_channel(
+                uuid(),
+                "  ###dev  ",
+                None::<Visibility>,
+                None::<ChannelKind>,
+                None,
+                None,
+            )
+            .unwrap(),
+        );
+        assert!(has_tag(&ev, "name", "dev"));
+    }
+
+    #[test]
+    fn create_channel_rejects_hash_only_name() {
+        assert!(matches!(
+            build_create_channel(
+                uuid(),
+                "  ###  ",
+                None::<Visibility>,
+                None::<ChannelKind>,
+                None,
+                None,
+            ),
+            Err(SdkError::InvalidTag(_))
+        ));
+    }
+
     #[test]
     fn create_channel_ephemeral_emits_ttl() {
         let cid = uuid();

crates/buzz-sdk/src/lib.rs

@@ -74,6 +74,8 @@ pub struct CustomEmoji {
     pub url: String,
 }
 
+/// Return a channel name without client-rendered leading hash prefixes.
+pub use buzz_core::channel::canonical_channel_name;
 /// Channel type.
 pub use buzz_core::channel::ChannelType as ChannelKind;
 /// Channel visibility.

desktop/src-tauri/src/events.rs

@@ -148,6 +148,10 @@ pub fn build_create_channel(
     about: Option<&str>,
     ttl_seconds: Option<i32>,
 ) -> Result<EventBuilder, String> {
+    let name = buzz_sdk_pkg::canonical_channel_name(name);
+    if name.trim().is_empty() {
+        return Err("channel name is required".into());
+    }
     let mut tags = vec![
         tag(vec!["h", &channel_id.to_string()])?,
         tag(vec!["name", name])?,
@@ -194,6 +198,10 @@ pub fn build_update_channel(
             return Err("visibility must be \"open\" or \"private\"".into());
         }
     }
+    let name = name.map(buzz_sdk_pkg::canonical_channel_name);
+    if name.is_some_and(|name| name.trim().is_empty()) {
+        return Err("channel name is required".into());
+    }
     let mut tags = vec![tag(vec!["h", &channel_id.to_string()])?];
     if let Some(n) = name {
         tags.push(tag(vec!["name", n])?);
@@ -842,7 +850,12 @@ pub fn build_approval_deny(token: &str, note: Option<&str>) -> Result<EventBuild
 mod tests {
     use super::*;
     use nostr::Keys;
-
+    #[test]
+    fn channel_builders_reject_hash_only_names() {
+        let channel_id = Uuid::new_v4();
+        assert!(build_create_channel(channel_id, "###", "open", "stream", None, None).is_err());
+        assert!(build_update_channel(channel_id, Some("###"), None, None, None).is_err());
+    }
     /// Builder layout regression for the NIP-IA owner-of-agent archive flow.
     /// Compares against `docs/nips/NIP-IA.md` §Vector 1.
     #[test]

desktop/src/features/channels/lib/canonicalChannelName.test.mjs

@@ -0,0 +1,22 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import {
+  canonicalChannelName,
+  channelNamesMatch,
+} from "./canonicalChannelName.ts";
+
+test("canonicalChannelName strips interleaved leading hashes and whitespace", () => {
+  assert.equal(canonicalChannelName("channel"), "channel");
+  assert.equal(canonicalChannelName("#channel"), "channel");
+  assert.equal(canonicalChannelName("  ### channel  "), "channel");
+  assert.equal(canonicalChannelName("# #"), "");
+  assert.equal(canonicalChannelName("### ###"), "");
+  assert.equal(canonicalChannelName("channel#topic"), "channel#topic");
+});
+
+test("channelNamesMatch canonicalizes both legacy names and search input", () => {
+  assert.equal(channelNamesMatch("#general", "general"), true);
+  assert.equal(channelNamesMatch("general", " #GENERAL "), true);
+  assert.equal(channelNamesMatch("#random", "general"), false);
+});

desktop/src/features/channels/lib/canonicalChannelName.ts

@@ -0,0 +1,14 @@
+/**
+ * Returns the stored form of a channel name after removing the display prefix.
+ * Keep this aligned with `buzz_core::channel::canonical_channel_name`.
+ */
+export function canonicalChannelName(name: string): string {
+  return name.replace(/^[#\s]+/u, "").trimEnd();
+}
+
+export function channelNamesMatch(left: string, right: string): boolean {
+  return (
+    canonicalChannelName(left).toLowerCase() ===
+    canonicalChannelName(right).toLowerCase()
+  );
+}

desktop/src/features/channels/ui/ChannelBrowserDialog.tsx

@@ -9,6 +9,10 @@ import {
 } from "lucide-react";
 
 import type { Channel } from "@/shared/api/types";
+import {
+  canonicalChannelName,
+  channelNamesMatch,
+} from "@/features/channels/lib/canonicalChannelName";
 import { scoreChannelMatch } from "@/features/channels/lib/channelSearchScore";
 import {
   type ChannelSortMode,
@@ -127,8 +131,9 @@ export function ChannelBrowserDialog({
     left: 0,
     width: 0,
   });
-  const deferredQuery = React.useDeferredValue(query.trim().toLowerCase());
-  const trimmedQuery = query.trim();
+  const canonicalQuery = canonicalChannelName(query);
+  const deferredQuery = React.useDeferredValue(canonicalQuery.toLowerCase());
+  const trimmedQuery = canonicalQuery;
   // Immediate (non-deferred) lowercased query. The create row's visibility
   // (via hasExactMatch) and its label both read from the live query so they
   // can never disagree for a frame while the fuzzy filter catches up.
@@ -244,7 +249,7 @@ export function ChannelBrowserDialog({
       channels.some(
         (channel) =>
           channel.channelType !== "dm" &&
-          channel.name.toLowerCase() === normalizedQuery &&
+          channelNamesMatch(channel.name, normalizedQuery) &&
           (channelTypeFilter
             ? channel.channelType === channelTypeFilter
             : true),