docs(buds): tracking-branch hint explains the BUD-number content guard

The override widget previously described only the fnmatch half of the
filter ("Open PRs are matched against this pattern on each impacted
repo. Supports fnmatch wildcards"). After the over-match fix added the
content guard that requires PRs to also reference the BUD by number,
that copy understated what surfaces a PR on a release-stage tab.

Rewrites the in-card hint and the dialog body so both rules are
visible. The example is now per-BUD: BUD-4 sees
``release/bud-001-bud-004``, BUD-12 sees ``release/bud-001-bud-012``.
Threads ``bud_number`` from BUDDetail → BUDReleaseStagePanel → the
override widget so the copy renders the actual reference, not a
placeholder.

Signed-off-by: Arun Rajkumar <mickyarunr@gmail.com>

Author: mickyarun

frontend/src/components/buds/BUDReleaseStagePanel.vue

@@ -21,6 +21,7 @@
          PR to materialise. -->
     <BUDStageBranchOverride
       :bud-id="budId"
+      :bud-number="budNumber"
       :stage="stage"
       :override="stageOverride"
       :default-branch="defaultStageBranch"
@@ -289,6 +290,10 @@ interface ImpactedRepo {
 
 const props = defineProps<{
   budId: string
+  /** This BUD's number. Threaded into the override widget so the helper
+   *  copy can reference ``bud-NNN`` concretely rather than as a
+   *  placeholder. */
+  budNumber: number
   stage: ReleaseStage
   /** Whether ANY impacted repo of this BUD has the relevant branch configured.
    *  Drives the empty-state CTA. Pass through from the parent. */

frontend/src/components/buds/BUDStageBranchOverride.vue

@@ -49,9 +49,11 @@
       </v-btn>
     </div>
     <div class="text-caption text-medium-emphasis mt-1">
-      Open PRs are matched against this pattern on each impacted repo.
-      Supports fnmatch wildcards — e.g. <code>release/*</code> matches
-      <code>release/2026-08-01</code>.
+      A PR appears here when its base branch matches this pattern
+      <strong>and</strong> its head branch or title carries
+      <code>bud-{{ budNumber }}</code>. Multi-BUD release branches like
+      <code>release/bud-001-bud-{{ paddedBudNumber }}</code> show up on
+      every referenced BUD.
     </div>
   </v-card>
 
@@ -68,6 +70,22 @@
           <code>{{ stage === 'uat' ? 'uat_branch' : 'main_branch' }}</code>
           setting.
         </p>
+        <p class="text-caption text-medium-emphasis mb-3">
+          A PR is surfaced only when both rules hold:
+        </p>
+        <ul class="text-caption text-medium-emphasis mb-3 ps-4">
+          <li>
+            Its base branch matches this pattern. Supports fnmatch
+            wildcards — <code>release/*</code> matches
+            <code>release/2026-08-01</code>.
+          </li>
+          <li>
+            Its head branch or title contains
+            <code>bud-{{ budNumber }}</code>. Release branches like
+            <code>release/bud-001-bud-{{ paddedBudNumber }}</code> match
+            this BUD and any other BUD also named in the branch.
+          </li>
+        </ul>
         <p
           v-if="impactedRepoCount > 1"
           class="text-caption text-medium-emphasis mb-3"
@@ -127,6 +145,10 @@ import type { ReleaseStage } from '@/types'
 
 const props = defineProps<{
   budId: string
+  /** This BUD's number — used by the helper copy so the rendered
+   *  example matches the actual BUD (``bud-4`` / ``bud-004``) instead
+   *  of a placeholder. */
+  budNumber: number
   stage: ReleaseStage
   /** The per-BUD pattern when set, ``null`` to fall back to the repo default. */
   override: string | null
@@ -161,6 +183,11 @@ const impactedRepoCount = computed(() => props.impactedRepoCount ?? 0)
 
 const stageLabel = computed(() => (props.stage === 'uat' ? 'UAT' : 'Production'))
 
+// Zero-padded form (``004``) for the multi-BUD example so the copy
+// mirrors the convention developers actually use when chaining BUDs
+// into a release branch.
+const paddedBudNumber = computed(() => String(props.budNumber).padStart(3, '0'))
+
 function cancel(): void {
   if (saving.value) return
   open.value = false

frontend/src/views/buds/BUDDetail.vue

@@ -369,6 +369,7 @@
               <v-tabs-window-item v-if="uatStageEnabled" value="uat">
                 <BUDReleaseStagePanel
                   :bud-id="bud.id"
+                  :bud-number="bud.bud_number"
                   stage="uat"
                   :has-stage-branch-configured="hasUatBranchConfigured"
                   :impacted-repos="bud.impacted_repos"
@@ -381,6 +382,7 @@
               <v-tabs-window-item value="prod">
                 <BUDReleaseStagePanel
                   :bud-id="bud.id"
+                  :bud-number="bud.bud_number"
                   stage="prod"
                   :has-stage-branch-configured="hasMainBranchConfigured"
                   :impacted-repos="bud.impacted_repos"