Implement RFD about LLM providers

acp-ktor-test/src/commonTest/kotlin/com/agentclientprotocol/SimpleAgentTest.kt

@@ -2001,6 +2001,88 @@ abstract class SimpleAgentTest(protocolDriver: ProtocolDriver) : ProtocolDriver
         assertEquals(1, sessions.size)
     }
 
+    @OptIn(UnstableApi::class)
+    @Test
+    fun `providers capability and methods are wired through client api`() = testWithProtocols { clientProtocol, agentProtocol ->
+        var lastSetProvider: SetProvidersRequest? = null
+        var lastDisabledProviderId: String? = null
+
+        val client = Client(protocol = clientProtocol)
+        Agent(protocol = agentProtocol, agentSupport = object : AgentSupport {
+            override suspend fun initialize(clientInfo: ClientInfo): AgentInfo {
+                return AgentInfo(
+                    clientInfo.protocolVersion,
+                    capabilities = AgentCapabilities(providers = ProvidersCapabilities())
+                )
+            }
+
+            override suspend fun listProviders(_meta: JsonElement?): ListProvidersResponse {
+                return ListProvidersResponse(
+                    providers = listOf(
+                        ProviderInfo(
+                            id = "main",
+                            supported = listOf(LlmProtocol.OPENAI, LlmProtocol.ANTHROPIC),
+                            required = false,
+                            current = ProviderCurrentConfig(
+                                apiType = LlmProtocol.OPENAI,
+                                baseUrl = "https://api.openai.com/v1"
+                            )
+                        ),
+                        ProviderInfo(
+                            id = "backup",
+                            supported = listOf(LlmProtocol.OPENAI),
+                            required = false
+                        )
+                    )
+                )
+            }
+
+            override suspend fun setProvider(
+                id: String,
+                apiType: LlmProtocol,
+                baseUrl: String,
+                headers: Map<String, String>?,
+                _meta: JsonElement?
+            ): SetProvidersResponse {
+                lastSetProvider = SetProvidersRequest(id, apiType, baseUrl, headers, _meta)
+                return SetProvidersResponse()
+            }
+
+            override suspend fun disableProvider(id: String, _meta: JsonElement?): DisableProvidersResponse {
+                lastDisabledProviderId = id
+                return DisableProvidersResponse()
+            }
+
+            override suspend fun createSession(sessionParameters: SessionCreationParameters): AgentSession {
+                TODO("Not needed for providers test")
+            }
+        })
+
+        val agentInfo = client.initialize(ClientInfo(protocolVersion = LATEST_PROTOCOL_VERSION))
+        assertNotNull(agentInfo.capabilities.providers)
+
+        val providersResponse = client.listProviders()
+        assertEquals(2, providersResponse.providers.size)
+        assertEquals("main", providersResponse.providers[0].id)
+        assertEquals(LlmProtocol.OPENAI, providersResponse.providers[0].current?.apiType)
+        assertNull(providersResponse.providers[1].current)
+
+        client.setProvider(
+            id = "main",
+            apiType = LlmProtocol.ANTHROPIC,
+            baseUrl = "https://api.anthropic.com",
+            headers = mapOf("x-api-key" to "test-key")
+        )
+        assertNotNull(lastSetProvider)
+        assertEquals("main", lastSetProvider.id)
+        assertEquals(LlmProtocol.ANTHROPIC, lastSetProvider.apiType)
+        assertEquals("https://api.anthropic.com", lastSetProvider.baseUrl)
+        assertEquals("test-key", lastSetProvider.headers?.get("x-api-key"))
+
+        client.disableProvider("main")
+        assertEquals("main", lastDisabledProviderId)
+    }
+
     @Test
     @OptIn(UnstableApi::class)
     fun `session ready notifies available commands`() = testWithProtocols { clientProtocol, agentProtocol ->

acp-model/.schema-checksums

@@ -3,9 +3,9 @@
 # Format: SHA256 FILENAME
 
 # Stable schemas
-07f2cdfd7814496ebdab83fb7417787fa1dddc6276b11cd31b51be2f8ba95f2b  schema/schema.json
-f242b95def9a9cbfddd2db1a45d8d3d489ad1b4f564a1322547c90a94c647637  schema/meta.json
+38751907a86016c73662ea2ad1ded2c8cbbdb99fe40b8368b6dd2794726be236  schema/schema.json
+71036d4c70f1e964c445569c1878a513e2fadfc797161d7582224b4647669330  schema/meta.json
 
 # Unstable schemas
-75d180b9c589cd7d79a5a9cbb6680d52e1bce71238839871441d30c753b497a9  schema/schema.unstable.json
-e87ae9b3fc3b05f88da6dfc06d003e5263d6a041b1c934ed13b83173b39ed111  schema/meta.unstable.json
+cb3cf31dae7e482dc45389f15e23edff037abaeccbffbe3b6d8eb1f9c00b88a5  schema/schema.unstable.json
+0a030d3641d0cbc71c433fc2ef68e33ee3c5707220c3ceb662ccb2e6f656e026  schema/meta.unstable.json

acp-model/.schema-revision

@@ -1 +1 @@
-37d12f4bb4b0cf1dca60421d48cb17decc119b8e
+a26839cc3ab0a746eff1fb95a02e87a5946ad631

acp-model/SCHEMA_VERSION.md

@@ -5,65 +5,63 @@ This file tracks the version of the Agent Client Protocol schema that the model
 ## Schema Source
 - Repository: https://github.com/agentclientprotocol/agent-client-protocol
 - Branch: main
-- Release: v0.9.1
+- Baseline commit: `a26839cc3ab0a746eff1fb95a02e87a5946ad631`
+- Baseline commit date: 2026-04-19 12:29:33 +0100
+- Baseline commit subject: `Optional current provider (#1021)`
 
 ## Schema Files
 
 ### Stable Schema
 - **schema.json**
-  - Commit: `37d12f4bb4b0cf1dca60421d48cb17decc119b8e`
-  - Date: 2025-12-20 18:25:51 +0000
-  - SHA256: `07f2cdfd7814496ebdab83fb7417787fa1dddc6276b11cd31b51be2f8ba95f2b`
+  - Commit: `a26839cc3ab0a746eff1fb95a02e87a5946ad631`
+  - Date: 2026-04-19 12:29:33 +0100
+  - SHA256: `38751907a86016c73662ea2ad1ded2c8cbbdb99fe40b8368b6dd2794726be236`
   - URL: https://github.com/agentclientprotocol/agent-client-protocol/blob/main/schema/schema.json
 
 - **meta.json**
-  - Commit: `37d12f4bb4b0cf1dca60421d48cb17decc119b8e`
-  - Date: 2025-12-20 18:25:51 +0000
-  - SHA256: `f242b95def9a9cbfddd2db1a45d8d3d489ad1b4f564a1322547c90a94c647637`
+  - Commit: `a26839cc3ab0a746eff1fb95a02e87a5946ad631`
+  - Date: 2026-04-19 12:29:33 +0100
+  - SHA256: `71036d4c70f1e964c445569c1878a513e2fadfc797161d7582224b4647669330`
   - URL: https://github.com/agentclientprotocol/agent-client-protocol/blob/main/schema/meta.json
 
 ### Unstable Schema
 - **schema.unstable.json**
-  - Commit: `37d12f4bb4b0cf1dca60421d48cb17decc119b8e`
-  - Date: 2025-12-20 18:25:51 +0000
-  - SHA256: `75d180b9c589cd7d79a5a9cbb6680d52e1bce71238839871441d30c753b497a9`
+  - Commit: `a26839cc3ab0a746eff1fb95a02e87a5946ad631`
+  - Date: 2026-04-19 12:29:33 +0100
+  - SHA256: `cb3cf31dae7e482dc45389f15e23edff037abaeccbffbe3b6d8eb1f9c00b88a5`
   - URL: https://github.com/agentclientprotocol/agent-client-protocol/blob/main/schema/schema.unstable.json
 
 - **meta.unstable.json**
-  - Commit: `37d12f4bb4b0cf1dca60421d48cb17decc119b8e`
-  - Date: 2025-12-20 18:25:51 +0000
-  - SHA256: `e87ae9b3fc3b05f88da6dfc06d003e5263d6a041b1c934ed13b83173b39ed111`
+  - Commit: `a26839cc3ab0a746eff1fb95a02e87a5946ad631`
+  - Date: 2026-04-19 12:29:33 +0100
+  - SHA256: `0a030d3641d0cbc71c433fc2ef68e33ee3c5707220c3ceb662ccb2e6f656e026`
   - URL: https://github.com/agentclientprotocol/agent-client-protocol/blob/main/schema/meta.unstable.json
 
 **Note:** All types from unstable schema must be marked with `@UnstableApi` annotation.
 
 ## Last Updated
-- Date: 2025-12-20
+- Date: 2026-04-19
 - Updated by: Manual schema synchronization
 
 ## Changes in This Version
-- Added `session/fork` method to agent methods (unstable)
-- Added `session/list` method to agent methods (unstable)
-- Added `session/resume` method to agent methods (unstable)
-- Added `session/set_config_option` method to agent methods (unstable)
-- Added `session/set_model` method to agent methods (unstable)
-- Added `$/cancel_request` protocol method (unstable)
-- Updated stable schema with bug fixes and improvements
+- `ProviderInfo.current` is optional now (`required` no longer includes `current`).
+- Disabled provider is valid both when `current` is omitted and when it is explicitly `null`.
+- Unstable providers schema (`providers/list`, `providers/set`, `providers/disable`) is synced to current `main` HEAD.
 
 ## Verification
 To verify the schema files match:
 ```bash
 # Stable schemas
 curl -s https://raw.githubusercontent.com/agentclientprotocol/agent-client-protocol/main/schema/schema.json | sha256sum
-# Expected: 07f2cdfd7814496ebdab83fb7417787fa1dddc6276b11cd31b51be2f8ba95f2b
+# Expected: 38751907a86016c73662ea2ad1ded2c8cbbdb99fe40b8368b6dd2794726be236
 
 curl -s https://raw.githubusercontent.com/agentclientprotocol/agent-client-protocol/main/schema/meta.json | sha256sum
-# Expected: f242b95def9a9cbfddd2db1a45d8d3d489ad1b4f564a1322547c90a94c647637
+# Expected: 71036d4c70f1e964c445569c1878a513e2fadfc797161d7582224b4647669330
 
 # Unstable schemas
 curl -s https://raw.githubusercontent.com/agentclientprotocol/agent-client-protocol/main/schema/schema.unstable.json | sha256sum
-# Expected: 75d180b9c589cd7d79a5a9cbb6680d52e1bce71238839871441d30c753b497a9
+# Expected: cb3cf31dae7e482dc45389f15e23edff037abaeccbffbe3b6d8eb1f9c00b88a5
 
 curl -s https://raw.githubusercontent.com/agentclientprotocol/agent-client-protocol/main/schema/meta.unstable.json | sha256sum
-# Expected: e87ae9b3fc3b05f88da6dfc06d003e5263d6a041b1c934ed13b83173b39ed111
+# Expected: 0a030d3641d0cbc71c433fc2ef68e33ee3c5707220c3ceb662ccb2e6f656e026
 ```