Adopt session.redirect (issue #710) (#714)

* Add session.redirect affordance (issue #710)

Route send through session.redirect while a turn is streaming and the prompt
is plain text (no attachments, not a /command); otherwise prompt.submit.
Adds WsMethods.SESSION_REDIRECT + HermesWsClient.sendRedirect. No separate
button — the composer already sends mid-turn, so send just does the redirect.

* fix(chat): capture typing state before sendMessage for redirect

Capture wasStreaming state before updating uiState.isAgentTyping so normal sends call prompt.submit.

---------

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

app/src/main/java/com/m57/hermescontrol/data/ws/HermesWsClient.kt

@@ -434,6 +434,23 @@ object HermesWsClient {
             onSent = onSent,
         )
 
+    /**
+     * Convenience: redirect the active model turn while it is still generating
+     * (backend `session.redirect`). Fire-and-forget — the backend either rewrites
+     * the live turn, queues the correction as the next turn, or rejects it (the
+     * caller's ViewModel handles the `4010` fall-back to [sendMessage]).
+     */
+    fun sendRedirect(
+        sessionId: String,
+        text: String,
+        onSent: ((String) -> Unit)? = null,
+    ): String =
+        send(
+            method = WsMethods.SESSION_REDIRECT,
+            params = mapOf("session_id" to sessionId, "text" to text),
+            onSent = onSent,
+        )
+
     // ── Internal ─────────────────────────────────────────────────────────
 
     private fun openSocket() {

app/src/main/java/com/m57/hermescontrol/data/ws/WsMethods.kt

@@ -10,6 +10,7 @@ object WsMethods {
     const val SESSION_RESUME = "session.resume"
     const val SESSION_CREATE = "session.create"
     const val SESSION_INTERRUPT = "session.interrupt"
+    const val SESSION_REDIRECT = "session.redirect"
     const val SESSION_DELETE = "session.delete"
     const val SESSION_TITLE = "session.title"
     const val SESSION_BRANCH = "session.branch"

app/src/main/java/com/m57/hermescontrol/ui/chat/ChatViewModel.kt

@@ -765,6 +765,8 @@ class ChatViewModel(
         val attachments = _uiState.value.pendingAttachments.toList()
         clearAttachments()
 
+        val wasStreaming = _uiState.value.isAgentTyping
+
         val userMessage =
             ChatMessage(
                 role = MessageRole.USER,
@@ -857,6 +859,18 @@ class ChatViewModel(
                         if (text.isNotBlank()) "\n\n$text" else ""
                 }
 
+            // While a turn is actively streaming and this is a plain text prompt
+            // (no attachments — session.redirect carries text only), steer the
+            // in-flight turn via session.redirect instead of queueing a fresh
+            // prompt.submit. The backend rewrites the live turn when it can, or
+            // queues the correction as the next turn otherwise (issue #710).
+            if (wasStreaming && attachments.isEmpty()) {
+                wsClient.sendRedirect(
+                    agentSessionId,
+                    fullText,
+                    onSent = { id -> trackRequest(id, WsMethods.SESSION_REDIRECT) },
+                )
+            } else {
                 wsClient.sendMessage(
                     agentSessionId,
                     fullText,
@@ -864,6 +878,7 @@ class ChatViewModel(
                 )
             }
         }
+    }
 
     /** Read and encode a `content://` or `file://` URI to Base64 via ContentResolver, avoiding large allocations. */
     private suspend fun readContentUriBase64(uriString: String): String? =

app/src/test/java/com/m57/hermescontrol/ui/chat/ChatViewModelTest.kt

@@ -1117,6 +1117,23 @@ class ChatViewModelTest {
             verify { HermesWsClient.sendMessage(sessionId, "Hello Hermes", any()) }
         }
 
+    @Test
+    fun testSendMessageRedirectWhenStreaming() =
+        runTest {
+            val (viewModel, sessionId) = createViewModelWithSession()
+
+            // First send starts streaming
+            viewModel.sendMessage("Hello Hermes")
+            advanceUntilIdle()
+            assertTrue(viewModel.uiState.value.isAgentTyping)
+
+            // Second send while streaming triggers redirect
+            viewModel.sendMessage("Wait, correction")
+            advanceUntilIdle()
+
+            verify { HermesWsClient.sendRedirect(sessionId, "Wait, correction", any()) }
+        }
+
     // ── Session switch ───────────────────────────────────────────────────────
 
     @Test