fix(sessions): show fork icon + order number on nested forked sessions (#934)

* fix(sessions): fork icon + depth number, no indentation

Multiply-nested forked sessions rendered with deep indentation that crushed
the card off-screen and made titles unreadable, and the per-sibling order
number was uninformative (mostly "1").

- SessionTreeItem: replace forkIndex (sibling order) with forkDepth (nesting
  level: 1 = child of a root, 2 = fork of a fork, ...); flattenSessionTree
  populates it.
- SessionCard: render CallSplit fork icon + the depth number (primary tint).
  Removed the depth-based start padding so names stay full-width readable —
  the icon+number now carries the structure instead of indentation.
- strings: sessions_fork_indicator (en/zh/ko).
- SessionTreeTest: assert isFork/forkDepth across nested fixtures.

No backend change — backend already returns parent_session_id per SessionInfo.

* test(ws): make testAutoReconnect tolerate transient RECONNECTING state

The test gated on connectionStatus.first { it == RECONNECTING } with a
15s timeout. With the test backoff forced to 0ms the RECONNECTING state is
emitted + consumed before the collector attaches, so the wait missed it and
timed out (kotlinx.coroutines.TimeoutCancellationException) — the flake CI
saw under parallel load.

- Replace the brittle RECONNECTING .first{} wait with a tolerant check that
  accepts RECONNECTING-or-later (the reconnect clearly fired).
- Keep connect2Latch (second socket opening) as the definitive proof + add a
  final CONNECTED assertion.
- Reset the test backoff in a finally so later tests never inherit 0ms.

---------

Co-authored-by: M57 <hy4ri@users.noreply.github.com>

app/src/main/java/com/m57/hermescontrol/data/model/SessionTreeItem.kt

@@ -4,9 +4,25 @@ data class SessionTreeItem(
     val session: SessionInfo,
     val depth: Int,
     val branchStem: String?,
+    // True when this session was forked/branched from another (has a parent in
+    // the loaded set). Drives the fork icon in SessionCard.
+    val isFork: Boolean = false,
+    // How many levels deep this fork sits (1 = direct child of a root, 2 = fork
+    // of a fork, ...). Shown as the number next to the fork icon so a nested
+    // chain reads 🍴1 → 🍴2 → 🍴3 and a branch-off pops out visually. 0 for
+    // non-forked (root) sessions.
+    val forkDepth: Int = 0,
     val displayTitle: String,
 )
 
+/**
+ * Flatten a session list into a display-order tree.
+ *
+ * Branching is expressed by `parent_session_id`. A session is a "fork" when its
+ * parent is present in the set; `forkDepth` is its nesting depth (1 = child of a
+ * root). The caller (SessionCard) renders a fork icon + the depth number so
+ * multiply-nested forks stay readable without deep indentation.
+ */
 fun flattenSessionTree(sessions: List<SessionInfo>): List<SessionTreeItem> {
     val ids = sessions.mapTo(mutableSetOf()) { it.id }
     val children = sessions.groupBy { it.parent_session_id?.takeIf(ids::contains) }
@@ -16,8 +32,8 @@ fun flattenSessionTree(sessions: List<SessionInfo>): List<SessionTreeItem> {
     fun append(
         session: SessionInfo,
         depth: Int,
-        branchStem: String?,
         siblingIndex: Int,
+        siblingCount: Int,
     ) {
         if (!visited.add(session.id)) return
         val isBranch = session.parent_session_id?.takeIf(ids::contains) != null
@@ -29,23 +45,32 @@ fun flattenSessionTree(sessions: List<SessionInfo>): List<SessionTreeItem> {
                 } else {
                     session.preview?.takeIf(String::isNotBlank)?.take(80) ?: "Untitled"
                 }
-        result += SessionTreeItem(session, depth, branchStem, title)
+        val branchStem = if (depth == 0) null else (if (siblingIndex == siblingCount - 1) "└─" else "├─")
+        result +=
+            SessionTreeItem(
+                session = session,
+                depth = depth,
+                branchStem = branchStem,
+                isFork = isBranch,
+                forkDepth = if (isBranch) depth else 0,
+                displayTitle = title,
+            )
         val descendants = children[session.id].orEmpty()
         descendants.forEachIndexed { index, child ->
             append(
                 session = child,
                 depth = depth + 1,
-                branchStem = if (index == descendants.lastIndex) "└─" else "├─",
                 siblingIndex = index,
+                siblingCount = descendants.size,
             )
         }
     }
 
     children[null].orEmpty().forEachIndexed { index, root ->
-        append(root, depth = 0, branchStem = null, siblingIndex = index)
+        append(root, depth = 0, siblingIndex = index, siblingCount = children[null].orEmpty().size)
     }
     sessions.filterNot { it.id in visited }.forEachIndexed { index, orphan ->
-        append(orphan, depth = 0, branchStem = null, siblingIndex = index)
+        append(orphan, depth = 0, siblingIndex = index, siblingCount = 1)
     }
     return result
 }

app/src/main/java/com/m57/hermescontrol/ui/sessions/SessionsScreen.kt

@@ -32,6 +32,7 @@ import androidx.compose.foundation.text.KeyboardActions
 import androidx.compose.foundation.text.KeyboardOptions
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.automirrored.filled.Send
+import androidx.compose.material.icons.filled.CallSplit
 import androidx.compose.material.icons.filled.CheckCircle
 import androidx.compose.material.icons.filled.Close
 import androidx.compose.material.icons.filled.Code
@@ -791,8 +792,9 @@ fun SessionsScreen(
                                     SessionCard(
                                         session = session,
                                         displayTitle = item.displayTitle,
-                                        depth = item.depth,
                                         branchStem = item.branchStem,
+                                        isFork = item.isFork,
+                                        forkDepth = item.forkDepth,
                                         query = state.searchQuery,
                                         isSelecting = state.isSelecting,
                                         isSelected = session.id in state.selectedIds,
@@ -958,8 +960,9 @@ fun SessionsScreen(
 private fun SessionCard(
     session: com.m57.hermescontrol.data.model.SessionInfo,
     displayTitle: String,
-    depth: Int,
     branchStem: String?,
+    isFork: Boolean = false,
+    forkDepth: Int = 0,
     query: String,
     isSelecting: Boolean,
     isSelected: Boolean,
@@ -984,7 +987,6 @@ private fun SessionCard(
         modifier =
             Modifier
                 .fillMaxWidth()
-                .padding(start = (depth * 16).dp)
                 .testTag("session_card_${session.id}")
                 .combinedClickable(
                     onClick = onCardClick,
@@ -1022,13 +1024,25 @@ private fun SessionCard(
                     Spacer(modifier = Modifier.width(spacing.sm))
                 }
 
-                // Branch tree stem
-                if (branchStem != null && !isSelecting) {
-                    Text(
-                        text = branchStem,
-                        style = MaterialTheme.typography.labelLarge,
-                        color = MaterialTheme.colorScheme.outline,
+                // Fork marker: a fork icon + its nesting depth, so a chain reads
+                // 🍴1 → 🍴2 → 🍴3 and a branch-off pops out. No indentation — the
+                // number carries the structure so names never get squished.
+                if (isFork && !isSelecting) {
+                    Icon(
+                        imageVector = Icons.Filled.CallSplit,
+                        contentDescription = stringResource(R.string.sessions_fork_indicator),
+                        tint = MaterialTheme.colorScheme.primary,
+                        modifier = Modifier.size(16.dp),
                     )
+                    if (forkDepth > 0) {
+                        Spacer(modifier = Modifier.width(spacing.xs))
+                        Text(
+                            text = forkDepth.toString(),
+                            style = MaterialTheme.typography.labelLarge,
+                            fontWeight = FontWeight.Bold,
+                            color = MaterialTheme.colorScheme.primary,
+                        )
+                    }
                     Spacer(modifier = Modifier.width(spacing.sm))
                 }
 

app/src/main/res/values-ko/strings.xml

@@ -347,6 +347,7 @@
     <string name="sessions_prune_desc">지정된 일수보다 오래된 세션을 삭제합니다.</string>
     <string name="sessions_prune_days_label">일수 기준</string>
     <string name="sessions_prune_confirm">정리</string>
+    <string name="sessions_fork_indicator">분기된 세션</string>
     <string name="sessions_delete_title">세션 삭제?</string>
     <string name="sessions_delete_message">정말 \"%1$s\"을(를) 삭제하시겠습니까? 되돌릴 수 없습니다.</string>
     <string name="sessions_bulk_delete_title">세션 삭제?</string>

app/src/main/res/values-zh/strings.xml

@@ -473,6 +473,7 @@
     <string name="sessions_action_pin">置顶</string>
     <string name="sessions_action_unpin">取消置顶</string>
     <string name="sessions_pinned_indicator">已置顶</string>
+    <string name="sessions_fork_indicator">分支会话</string>
     <string name="sessions_rename_title">重命名会话</string>
     <string name="sessions_rename_hint">会话标题</string>
     <string name="toolsets_empty_title">没有工具集数据</string>

app/src/main/res/values/strings.xml

@@ -548,6 +548,7 @@
     <string name="sessions_action_pin">Pin</string>
     <string name="sessions_action_unpin">Unpin</string>
     <string name="sessions_pinned_indicator">Pinned</string>
+    <string name="sessions_fork_indicator">Forked session</string>
     <string name="sessions_rename_title">Rename Session</string>
     <string name="sessions_rename_hint">Session title</string>
 

app/src/test/java/com/m57/hermescontrol/data/model/SessionTreeTest.kt

@@ -25,7 +25,29 @@ class SessionTreeTest {
                 it.displayTitle
             },
         )
-        assertEquals(listOf(null, null, "├─", "└─", "└─"), tree.map { it.branchStem })
+        // Fork flag + nesting depth (1 = child of root, 2 = fork of a fork).
+        assertEquals(listOf(false, false, true, true, true), tree.map { it.isFork })
+        assertEquals(listOf(0, 0, 1, 1, 2), tree.map { it.forkDepth })
+    }
+
+    @Test
+    fun deepNestingMarksEveryForkWithDepth() {
+        // root → a (child 1) → a1 (child 1) ; root → b (child 2, last)
+        // a1 is fork-depth 2 (fork of a fork), b is fork-depth 1.
+        val sessions =
+            listOf(
+                SessionInfo(id = "root", title = "Root"),
+                SessionInfo(id = "a", parent_session_id = "root"),
+                SessionInfo(id = "b", parent_session_id = "root"),
+                SessionInfo(id = "a1", parent_session_id = "a"),
+            )
+
+        val tree = flattenSessionTree(sessions)
+
+        assertEquals(listOf("root", "a", "a1", "b"), tree.map { it.session.id })
+        assertEquals(listOf(0, 1, 2, 1), tree.map { it.depth })
+        assertEquals(listOf(false, true, true, true), tree.map { it.isFork })
+        assertEquals(listOf(0, 1, 2, 1), tree.map { it.forkDepth })
     }
 
     @Test

app/src/test/java/com/m57/hermescontrol/data/ws/HermesWsClientTest.kt

@@ -1099,20 +1099,33 @@ class HermesWsClientTest {
         // Force server to close socket 1 to trigger reconnect
         serverSocket1?.close(1001, "Server shutting down")
 
-        // Wait for status to become RECONNECTING
-        runBlocking {
-            withTimeout(
-                15_000,
-            ) { HermesWsClient.connectionStatus.first { it == ConnectionStatus.RECONNECTING } }
-        }
+        // Wait for the reconnect to trigger. With the test backoff forced to
+        // 0ms the RECONNECTING state is transient and can be emitted + consumed
+        // before this collector attaches, so we don't gate on the exact
+        // intermediate state — we require it to have progressed (RECONNECTING
+        // or later). The definitive proof is the second socket opening below.
+        val statusNow = HermesWsClient.connectionStatus.value
+        assertTrue(
+            "Expected reconnect to trigger (RECONNECTING or later), was $statusNow",
+            statusNow == ConnectionStatus.RECONNECTING ||
+                statusNow == ConnectionStatus.CONNECTING ||
+                statusNow == ConnectionStatus.CONNECTED,
+        )
 
-        // The client should now attempt to reconnect after initial backoff (1000ms)
+        // The client should now attempt to reconnect after the (0ms) backoff.
         // Wait for the second connection to hit the server. Generous ceiling:
         // loaded CI runners routinely stretch short wall-clock windows.
-        assertTrue("Failed to reconnect", connect2Latch.await(30, TimeUnit.SECONDS))
-
-        // Restore production backoff so later tests see the default.
-        HermesWsClient.setReconnectBackoffForTest(1_000L)
+        try {
+            assertTrue("Failed to reconnect", connect2Latch.await(30, TimeUnit.SECONDS))
+            runBlocking {
+                withTimeout(15_000) { HermesWsClient.connectionStatus.first { it == ConnectionStatus.CONNECTED } }
+            }
+            assertEquals(ConnectionStatus.CONNECTED, HermesWsClient.connectionStatus.value)
+        } finally {
+            // Restore production backoff so later tests see the default, even
+            // if an assertion above threw.
+            HermesWsClient.setReconnectBackoffForTest(1_000L)
+        }
     }
 
     // ── TEST-10: WS reconnect state recovery ────────────────────────────