feat: skip agent triggering on /note-prefixed comments (MUL-3115, #3649) (#3885)

* feat(comments): skip agent triggering on /note-prefixed comments

A comment whose first token is the reserved /note prefix (case-insensitive)
is stored like any other comment but never wakes an agent. The guard sits at
the top of triggerTasksForComment, the single chokepoint, so it covers all
three trigger paths — assignee, squad leader, and @mentioned agents. Gating
only shouldEnqueueOnComment (as originally proposed) would still let
"/note @agent ..." through the mention path.

Lets members leave human-only tips/notes on agent-assigned issues without
burning an agent run. MUL-3115, closes #3649.

Co-authored-by: multica-agent <github@multica.ai>

* feat(editor): add /note built-in slash command to comment composer

Enable the `/` menu in the issue comment and reply composers in a new
"command" mode that lists fixed built-in commands instead of the chat
skill picker. Currently one command, /note, which marks a comment as a
human-only note that won't trigger the assigned agent.

Selecting it inserts the plain-text "/note " prefix (not a rich node), so
a menu pick and a hand-typed command are byte-identical and the backend
detects either with a simple prefix match. The command menu renders nothing
on a non-matching `/` (hideOnEmpty) so typing a date like 6/8 isn't noisy.
The chat skill picker is unchanged. MUL-3115.

Co-authored-by: multica-agent <github@multica.ai>

* refactor(editor): match /note by label prefix and localize its description

Address PR review feedback:
- buildBuiltinCommandItems now matches the command label as a prefix only,
  dropping the description substring match copied from the skill picker. With
  one command this keeps the menu predictable (/no surfaces note; /deploy or a
  description word like /agent shows nothing) and avoids Enter selecting note
  unexpectedly.
- The command description is now a localized UI string: added
  slash_command.commands.note to all four editor locales (en/ja/ko/zh-Hans)
  and the menu renders it via the typed translator. The /label itself stays
  literal since it's the typed token the backend matches.

MUL-3115.

Co-authored-by: multica-agent <github@multica.ai>

* fix(editor): shorten /note command description to avoid truncation

The slash menu item is single-line (truncate, w-72), so the longer copy was
cut off. Shorten to "won't trigger any agents" across all four locales — also
more accurate, since /note skips assignee, squad leader, and @mentioned agents,
not just the assigned one.

MUL-3115.

Co-authored-by: multica-agent <github@multica.ai>

---------

Co-authored-by: J <j@multica.ai>
Co-authored-by: multica-agent <github@multica.ai>

server/internal/handler/comment.go

@@ -6,7 +6,9 @@ import (
 	"log/slog"
 	"net/http"
 	"strconv"
+	"strings"
 	"time"
+	"unicode"
 
 	"github.com/go-chi/chi/v5"
 	"github.com/jackc/pgx/v5/pgtype"
@@ -928,7 +930,35 @@ func (h *Handler) CreateComment(w http.ResponseWriter, r *http.Request) {
 	writeJSON(w, http.StatusCreated, resp)
 }
 
+// noteCommentPrefix marks a comment as a human-only note. A comment whose first
+// whitespace-delimited token is this prefix (case-insensitive) is stored like
+// any other comment but never triggers an agent — see triggerTasksForComment.
+const noteCommentPrefix = "/note"
+
+// isNoteComment reports whether content opts out of agent triggering via the
+// reserved /note prefix. The prefix must be the comment's first token, so
+// "/note check expiry", "  /NOTE", and "/note" all match, while "/notes",
+// "/ note", and "see foo/note" do not.
+func isNoteComment(content string) bool {
+	trimmed := strings.TrimLeft(content, " \t\r\n")
+	firstToken := trimmed
+	if i := strings.IndexFunc(trimmed, unicode.IsSpace); i >= 0 {
+		firstToken = trimmed[:i]
+	}
+	return strings.EqualFold(firstToken, noteCommentPrefix)
+}
+
 func (h *Handler) triggerTasksForComment(ctx context.Context, issue db.Issue, comment db.Comment, parentComment *db.Comment, actorType, actorID string) {
+	// A comment opening with the reserved /note prefix is a human-only note: it
+	// is recorded like any other comment but must not wake ANY agent. This guard
+	// lives at the single chokepoint so it covers all three trigger paths below
+	// (assignee, squad leader, and @mentioned agents). Gating only
+	// shouldEnqueueOnComment would still let "/note @agent ..." reach an agent
+	// through the mention path.
+	if isNoteComment(comment.Content) {
+		return
+	}
+
 	if actorType == "member" && h.shouldEnqueueOnComment(ctx, issue, actorType, actorID) &&
 		!h.commentMentionsOthersButNotAssignee(comment.Content, issue) &&
 		!h.isReplyToMemberThread(ctx, parentComment, comment.Content, issue) {

server/internal/handler/trigger_test.go

@@ -315,3 +315,55 @@ func TestOnCommentTriggerDecision(t *testing.T) {
 		})
 	}
 }
+
+// -------------------------------------------------------------------
+// isNoteComment — the /note opt-out prefix
+// -------------------------------------------------------------------
+
+func TestIsNoteComment(t *testing.T) {
+	tests := []struct {
+		name    string
+		content string
+		want    bool
+	}{
+		{"plain comment triggers", "just a plain comment", false},
+		{"note prefix skips", "/note check the API expiry", true},
+		{"bare note skips", "/note", true},
+		{"uppercase note skips (case-insensitive)", "/NOTE shout", true},
+		{"mixed case note skips", "/Note mixed", true},
+		{"leading whitespace tolerated", "   /note leading space", true},
+		{"note followed by newline skips", "/note\nmultiline body", true},
+		{"plural notes does not match (word boundary)", "/notes are plural", false},
+		{"noteworthy does not match", "/noteworthy idea", false},
+		{"slash space note does not match", "/ note has a space", false},
+		{"mid-sentence note does not match", "see foo/note here", false},
+		{"note as second token does not match", "fyi /note", false},
+		{"empty content does not match", "", false},
+		{"whitespace-only content does not match", "   ", false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := isNoteComment(tt.content); got != tt.want {
+				t.Errorf("isNoteComment(%q) = %v, want %v", tt.content, got, tt.want)
+			}
+		})
+	}
+}
+
+// TestTriggerTasksForComment_NoteShortCircuits proves a /note comment returns
+// before any of the three enqueue paths run. shouldEnqueueOnComment,
+// shouldEnqueueSquadLeaderOnComment, and enqueueMentionedAgentTasks all
+// dereference h.Queries, so a nil-Queries Handler would panic if the /note
+// guard were missing or moved below them. The comment also @mentions an agent
+// to exercise the mention path specifically.
+func TestTriggerTasksForComment_NoteShortCircuits(t *testing.T) {
+	h := &Handler{} // nil Queries / TaskService on purpose
+	issue := issueWithAgentAssignee()
+	comment := db.Comment{
+		Content: fmt.Sprintf("/note cc [@Other](mention://agent/%s) just an fyi", otherAgentID),
+	}
+
+	// Must not panic — the guard short-circuits before any DB access.
+	h.triggerTasksForComment(context.Background(), issue, comment, nil, "member", memberID)
+}