diff --git a/app/src/main/java/com/yugahashimoto/andcode/core/api/OpenCodeApiModels.kt b/app/src/main/java/com/yugahashimoto/andcode/core/api/OpenCodeApiModels.kt
index 6cc6922cb..c898e79ed 100644
--- a/app/src/main/java/com/yugahashimoto/andcode/core/api/OpenCodeApiModels.kt
+++ b/app/src/main/java/com/yugahashimoto/andcode/core/api/OpenCodeApiModels.kt
@@ -165,8 +165,24 @@ data class OpenCodeAgent(
     val description: String? = null,
     val mode: String? = null,
     val native: Boolean = false,
+    val hidden: Boolean = false,
 )
 
+/**
+ * The agents a user can start a chat with: OpenCode's primary (and `all`) agents, minus the hidden
+ * internal ones (compaction, title, summary). Plugin-defined primaries such as oh-my-opencode-slim's
+ * `orchestrator` are included.
+ *
+ * Server order is kept on purpose: OpenCode's `GET /agent` sorts its configured `default_agent`
+ * first (or `build` when none is set), so [defaultAgentName] follows the server's choice instead of
+ * hard-coding `build`.
+ */
+fun List<OpenCodeAgent>.selectablePrimaryAgents(): List<OpenCodeAgent> =
+    filter { (it.mode == null || it.mode == "primary" || it.mode == "all") && !it.hidden }
+
+/** The server's default agent: the first selectable primary it lists, or null when it offers none. */
+fun List<OpenCodeAgent>.defaultAgentName(): String? = selectablePrimaryAgents().firstOrNull()?.name
+
 @Serializable
 data class OpenCodeProject(
     val id: String,
diff --git a/app/src/main/java/com/yugahashimoto/andcode/data/settings/AppPreferencesRepository.kt b/app/src/main/java/com/yugahashimoto/andcode/data/settings/AppPreferencesRepository.kt
index 6beef9dc0..ac0c39531 100644
--- a/app/src/main/java/com/yugahashimoto/andcode/data/settings/AppPreferencesRepository.kt
+++ b/app/src/main/java/com/yugahashimoto/andcode/data/settings/AppPreferencesRepository.kt
@@ -2,6 +2,8 @@ package com.yugahashimoto.andcode.data.settings
 
 import com.yugahashimoto.andcode.core.api.OpenCodeAgent
 import com.yugahashimoto.andcode.core.api.ProviderCatalog
+import com.yugahashimoto.andcode.core.api.defaultAgentName
+import com.yugahashimoto.andcode.core.api.selectablePrimaryAgents
 import com.yugahashimoto.andcode.data.connection.SecureSettingsRepository
 import com.yugahashimoto.andcode.feature.assistant.TtsTuning
 import com.yugahashimoto.andcode.feature.wakeword.WakeWordGrammar
@@ -144,11 +146,10 @@ class AppPreferencesRepository(
         ) {
             selectModel(reconciled.providerId, reconciled.modelId)
         }
-        val primaryAgents = agents.filter { it.mode == null || it.mode == "primary" }
+        val primaryAgents = agents.selectablePrimaryAgents()
         val agentId =
             current.agentId?.takeIf { selected -> primaryAgents.any { it.name == selected } }
-                ?: primaryAgents.firstOrNull { it.name == "build" }?.name
-                ?: primaryAgents.firstOrNull()?.name
+                ?: agents.defaultAgentName()
         if (agentId != current.agentId) {
             selectAgent(agentId)
         }
diff --git a/app/src/main/java/com/yugahashimoto/andcode/feature/assistant/AssistantProfile.kt b/app/src/main/java/com/yugahashimoto/andcode/feature/assistant/AssistantProfile.kt
index cce1cc72d..3a2232219 100644
--- a/app/src/main/java/com/yugahashimoto/andcode/feature/assistant/AssistantProfile.kt
+++ b/app/src/main/java/com/yugahashimoto/andcode/feature/assistant/AssistantProfile.kt
@@ -2,6 +2,7 @@ package com.yugahashimoto.andcode.feature.assistant
 
 import com.yugahashimoto.andcode.core.api.OpenCodeAgent
 import com.yugahashimoto.andcode.core.api.OpenCodeProvider
+import com.yugahashimoto.andcode.core.api.defaultAgentName
 import com.yugahashimoto.andcode.data.connection.ConnectionProfile
 
 data class AssistantProfile(
@@ -53,7 +54,7 @@ object AssistantProfileResolver {
             val agentId =
                 profile.agentId
                     ?.takeIf { configured -> agents.any { it.name == configured } }
-                    ?: agents.firstOrNull { it.name == "build" }?.name
+                    ?: agents.defaultAgentName()
                     ?: agents.firstOrNull()?.name
 
             ResolvedAssistantProfile(
diff --git a/app/src/main/java/com/yugahashimoto/andcode/feature/chat/ChatHomeScreen.kt b/app/src/main/java/com/yugahashimoto/andcode/feature/chat/ChatHomeScreen.kt
index 673cfcc5e..e3b7a1749 100644
--- a/app/src/main/java/com/yugahashimoto/andcode/feature/chat/ChatHomeScreen.kt
+++ b/app/src/main/java/com/yugahashimoto/andcode/feature/chat/ChatHomeScreen.kt
@@ -131,6 +131,8 @@ import com.yugahashimoto.andcode.core.api.OpenCodeCommand
 import com.yugahashimoto.andcode.core.api.OpenCodeProvider
 import com.yugahashimoto.andcode.core.api.OpenCodeSkill
 import com.yugahashimoto.andcode.core.api.PromptAttachment
+import com.yugahashimoto.andcode.core.api.defaultAgentName
+import com.yugahashimoto.andcode.core.api.selectablePrimaryAgents
 import com.yugahashimoto.andcode.core.diagnostics.StallDiagnosis
 import com.yugahashimoto.andcode.core.diagnostics.StallReason
 import com.yugahashimoto.andcode.core.diagnostics.explain
@@ -1864,15 +1866,19 @@ private fun ModeChip(
     onSelect: (String) -> Unit,
 ) {
     var expanded by remember { mutableStateOf(false) }
-    // OpenCode servers can report arbitrary custom agents alongside its two built-ins; this chip
-    // only offers build/plan to keep the picker to the two modes users actually switch between.
-    // Fall back to the full list if a server configuration omits both, rather than showing an
-    // unusable empty dropdown.
-    val selectableAgents = agents.filter { it.name == "build" || it.name == "plan" }.ifEmpty { agents }
+    // Every primary agent the server reports is offered, not just build/plan: plugins such as
+    // oh-my-opencode-slim register their own primary (`orchestrator`), and hiding it left users
+    // unable to reach it. `agents` is normally narrowed upstream already; filtering again keeps
+    // subagents and OpenCode's internal compaction/title/summary agents out even if a caller
+    // passes the raw list.
+    val selectableAgents = agents.selectablePrimaryAgents()
     // The selection is remembered across runtimes, so an id this runtime does not offer would
     // otherwise label the chip with another agent's name. An empty list is not a licence to trust
     // it either: that is exactly the state a stopped runtime is in.
-    val label = selectedAgentId?.takeIf { id -> selectableAgents.any { it.name == id } } ?: "build"
+    val label =
+        selectedAgentId?.takeIf { id -> selectableAgents.any { it.name == id } }
+            ?: agents.defaultAgentName()
+            ?: "build"
     Box {
         Surface(
             modifier =
diff --git a/app/src/main/java/com/yugahashimoto/andcode/feature/settings/SettingsViewModel.kt b/app/src/main/java/com/yugahashimoto/andcode/feature/settings/SettingsViewModel.kt
index 6b8e6121b..d8e741171 100644
--- a/app/src/main/java/com/yugahashimoto/andcode/feature/settings/SettingsViewModel.kt
+++ b/app/src/main/java/com/yugahashimoto/andcode/feature/settings/SettingsViewModel.kt
@@ -6,6 +6,7 @@ import com.yugahashimoto.andcode.core.api.OpenCodeAgent
 import com.yugahashimoto.andcode.core.api.OpenCodeProvider
 import com.yugahashimoto.andcode.core.api.ProviderAuthMethod
 import com.yugahashimoto.andcode.core.api.ProviderCatalog
+import com.yugahashimoto.andcode.core.api.selectablePrimaryAgents
 import com.yugahashimoto.andcode.core.security.SecretRedaction
 import com.yugahashimoto.andcode.data.connection.SecureSettingsRepository
 import com.yugahashimoto.andcode.data.repository.RuntimeCatalogRepository
@@ -204,7 +205,7 @@ class SettingsViewModel(
                 providers = core.runtime.providers.all.filter { it.id in chatConnected },
                 availableProviders = managed.all,
                 connectedProviderIds = (managed.connected.toSet() + oauth.locallyConnected) - oauth.locallyDisconnected,
-                agents = core.runtime.agents.filter { it.mode == null || it.mode == "primary" },
+                agents = core.runtime.agents.selectablePrimaryAgents(),
                 providerId = core.preferences.providerId,
                 modelId = core.preferences.modelId,
                 agentId = core.preferences.agentId,
diff --git a/app/src/test/java/com/yugahashimoto/andcode/core/api/OpenCodeAgentSelectionTest.kt b/app/src/test/java/com/yugahashimoto/andcode/core/api/OpenCodeAgentSelectionTest.kt
new file mode 100644
index 000000000..cbb34e6f6
--- /dev/null
+++ b/app/src/test/java/com/yugahashimoto/andcode/core/api/OpenCodeAgentSelectionTest.kt
@@ -0,0 +1,77 @@
+package com.yugahashimoto.andcode.core.api
+
+import kotlinx.serialization.json.Json
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNull
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+class OpenCodeAgentSelectionTest {
+    // The shape OpenCode's GET /agent returns with oh-my-opencode-slim installed and
+    // `default_agent: "orchestrator"`: the default first, then build, then the rest by name.
+    private val pluginAgents =
+        listOf(
+            OpenCodeAgent("orchestrator", mode = "primary"),
+            OpenCodeAgent("build", mode = "primary", native = true),
+            OpenCodeAgent("compaction", mode = "primary", native = true, hidden = true),
+            OpenCodeAgent("council", mode = "subagent"),
+            OpenCodeAgent("councillor-gpt", mode = "subagent", hidden = true),
+            OpenCodeAgent("fixer", mode = "subagent"),
+            OpenCodeAgent("plan", mode = "primary", native = true),
+            OpenCodeAgent("summary", mode = "primary", native = true, hidden = true),
+            OpenCodeAgent("title", mode = "primary", native = true, hidden = true),
+        )
+
+    @Test
+    fun `offers plugin primaries alongside build and plan, but not subagents or hidden agents`() {
+        assertEquals(
+            listOf("orchestrator", "build", "plan"),
+            pluginAgents.selectablePrimaryAgents().map { it.name },
+        )
+    }
+
+    @Test
+    fun `offers agents whose mode is all or unreported`() {
+        val agents =
+            listOf(
+                OpenCodeAgent("build", mode = "primary"),
+                OpenCodeAgent("both", mode = "all"),
+                OpenCodeAgent("legacy"),
+            )
+
+        assertEquals(listOf("build", "both", "legacy"), agents.selectablePrimaryAgents().map { it.name })
+    }
+
+    @Test
+    fun `defaults to the agent the server lists first, which is its default_agent`() {
+        assertEquals("orchestrator", pluginAgents.defaultAgentName())
+    }
+
+    @Test
+    fun `defaults to build on a stock server`() {
+        val stock =
+            listOf(
+                OpenCodeAgent("build", mode = "primary", native = true),
+                OpenCodeAgent("plan", mode = "primary", native = true),
+            )
+
+        assertEquals("build", stock.defaultAgentName())
+    }
+
+    @Test
+    fun `has no default when the runtime reports no agents`() {
+        assertNull(emptyList<OpenCodeAgent>().defaultAgentName())
+    }
+
+    @Test
+    fun `decodes the hidden flag and treats a missing one as visible`() {
+        val json = Json { ignoreUnknownKeys = true }
+        val agents =
+            json.decodeFromString<List<OpenCodeAgent>>(
+                """[{"name":"title","mode":"primary","hidden":true,"native":true},{"name":"orchestrator","mode":"primary"}]""",
+            )
+
+        assertTrue(agents[0].hidden)
+        assertEquals(listOf("orchestrator"), agents.selectablePrimaryAgents().map { it.name })
+    }
+}
diff --git a/app/src/test/java/com/yugahashimoto/andcode/feature/assistant/AssistantProfileTest.kt b/app/src/test/java/com/yugahashimoto/andcode/feature/assistant/AssistantProfileTest.kt
index 6854f5238..bced598b8 100644
--- a/app/src/test/java/com/yugahashimoto/andcode/feature/assistant/AssistantProfileTest.kt
+++ b/app/src/test/java/com/yugahashimoto/andcode/feature/assistant/AssistantProfileTest.kt
@@ -42,6 +42,25 @@ class AssistantProfileTest {
         assertEquals("build", result.agentId)
     }
 
+    @Test
+    fun `missing agent follows the server's default_agent rather than build`() {
+        val result =
+            AssistantProfileResolver.resolve(
+                profile = AssistantProfile(backendId = "mac"),
+                connections = listOf(connection),
+                providers = listOf(provider),
+                defaultModels = mapOf("opencode" to "free"),
+                agents =
+                    listOf(
+                        OpenCodeAgent(name = "orchestrator", mode = "primary"),
+                        OpenCodeAgent(name = "build", mode = "primary"),
+                        OpenCodeAgent(name = "fixer", mode = "subagent"),
+                    ),
+            ).getOrThrow()
+
+        assertEquals("orchestrator", result.agentId)
+    }
+
     @Test
     fun `deleted backend produces configuration error`() {
         val result =