refactor(caching): give ContextCacheConfig an ADK-owned HttpOptions type

`ContextCacheConfig.createHttpOptions` was typed with the GenAI SDK's
`HttpOptions`, leaking a backend SDK type into ADK's public configuration API.
Add `com.google.adk.kt.models.HttpOptions` and use that instead;

PiperOrigin-RevId: 955731480

Author: damianmomotgoogle

core/src/commonMain/kotlin/com/google/adk/kt/agents/ContextCacheConfig.kt

@@ -17,7 +17,7 @@
 package com.google.adk.kt.agents
 
 import com.google.adk.kt.annotations.ExperimentalContextCachingFeature
-import com.google.genai.kotlin.types.HttpOptions
+import com.google.adk.kt.types.HttpOptions
 import kotlin.time.Duration
 import kotlin.time.Duration.Companion.seconds
 
@@ -42,10 +42,10 @@ import kotlin.time.Duration.Companion.seconds
  *   session; caching begins on the second turn once a previous token count is known. Context cache
  *   storage may have a cost, so set this higher to avoid caching small requests where the overhead
  *   may exceed the benefits. Must be non-negative. Defaults to 0.
- * @property createHttpOptions Optional HTTP options to pass to the GenAI client. Set this to add a
- *   timeout on `CachedContent.create()` calls (e.g. `HttpOptions(timeout=10000)` for a 10-second
- *   timeout in milliseconds). When the cache creation call exceeds the timeout, it fails and the
- *   request proceeds without caching. `null` uses the client's default HTTP options.
+ * @property createHttpOptions Optional HTTP options for the cache-creation call. Set this to add a
+ *   timeout on `CachedContent.create()` calls (e.g. `HttpOptions(timeout = 10.seconds)`). When the
+ *   cache creation call exceeds the timeout, it fails and the request proceeds without caching.
+ *   `null` uses the model backend's default HTTP options.
  */
 data class ContextCacheConfig
 @ExperimentalContextCachingFeature

core/src/commonMain/kotlin/com/google/adk/kt/models/GeminiContextCacheManager.kt

@@ -20,10 +20,10 @@ import com.google.adk.kt.crypto.sha256Hex
 import com.google.adk.kt.logging.LoggerFactory
 import com.google.adk.kt.serialization.adkJson
 import com.google.adk.kt.types.Content
+import com.google.adk.kt.types.HttpOptions
 import com.google.adk.kt.types.Role
 import com.google.adk.kt.types.Tool
 import com.google.adk.kt.types.ToolConfig
-import com.google.genai.kotlin.types.HttpOptions
 import kotlin.time.Clock
 import kotlin.time.Duration
 import kotlinx.serialization.json.JsonArray

core/src/commonMain/kotlin/com/google/adk/kt/models/GenaiCacheClient.kt

@@ -37,7 +37,7 @@ internal class GenaiCacheClient(private val caches: Caches) :
         toolConfig = request.toolConfig?.toGenaiSdk(),
         ttl = request.ttl,
         displayName = request.displayName,
-        httpOptions = request.httpOptions,
+        httpOptions = request.httpOptions?.toGenaiSdk(),
       )
     val cachedContent = caches.create(request.model, config)
     return cachedContent.name ?: throw IllegalStateException("Created cache has no resource name.")

core/src/commonMain/kotlin/com/google/adk/kt/types/GenaiConverters.kt

@@ -46,6 +46,7 @@ import com.google.genai.kotlin.types.GroundingChunkRetrievedContext as GenAiGrou
 import com.google.genai.kotlin.types.GroundingChunkWeb as GenAiGroundingChunkWeb
 import com.google.genai.kotlin.types.GroundingMetadata as GenAiGroundingMetadata
 import com.google.genai.kotlin.types.GroundingSupport as GenAiGroundingSupport
+import com.google.genai.kotlin.types.HttpOptions as GenAiHttpOptions
 import com.google.genai.kotlin.types.LogprobsResult as GenAiLogprobsResult
 import com.google.genai.kotlin.types.LogprobsResultCandidate as GenAiLogprobsResultCandidate
 import com.google.genai.kotlin.types.LogprobsResultTopCandidates as GenAiLogprobsResultTopCandidates
@@ -881,3 +882,13 @@ internal fun ThinkingConfig.toGenaiSdk(): GenAiThinkingConfig =
     thinkingBudget = thinkingBudget,
     thinkingLevel = thinkingLevel?.toGenaiSdk(),
   )
+
+// --- HttpOptions ---
+/** Converts an ADK [HttpOptions] to a [GenAiHttpOptions] for the GenAI SDK. */
+internal fun HttpOptions.toGenaiSdk(): GenAiHttpOptions =
+  GenAiHttpOptions(
+    baseUrl = baseUrl,
+    apiVersion = apiVersion,
+    headers = headers,
+    timeout = timeout?.inWholeMilliseconds?.toInt(),
+  )

core/src/commonMain/kotlin/com/google/adk/kt/types/HttpOptions.kt

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2026 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.adk.kt.types
+
+import kotlin.time.Duration
+
+/**
+ * ADK-owned HTTP transport options for calls a [com.google.adk.kt.models.Model] makes to its
+ * backend.
+ *
+ * This is ADK's own type rather than the backend SDK's, so that configuration surfaces such as
+ * [com.google.adk.kt.agents.ContextCacheConfig] stay independent of any particular backend.
+ * Implementations translate it to whatever their transport expects.
+ *
+ * @property baseUrl Base URL of the service endpoint. `null` uses the backend's default.
+ * @property apiVersion Version of the API to use. `null` uses the backend's default.
+ * @property headers Additional HTTP headers to send with the request.
+ * @property timeout Request timeout, e.g. `10.seconds`. `null` uses the backend's default.
+ */
+data class HttpOptions(
+  val baseUrl: String? = null,
+  val apiVersion: String? = null,
+  val headers: Map<String, String>? = null,
+  val timeout: Duration? = null,
+)

core/src/commonTest/kotlin/com/google/adk/kt/agents/ContextCacheConfigTest.kt

@@ -18,7 +18,7 @@
 
 package com.google.adk.kt.agents
 
-import com.google.genai.kotlin.types.HttpOptions
+import com.google.adk.kt.types.HttpOptions
 import kotlin.test.Test
 import kotlin.test.assertEquals
 import kotlin.test.assertFailsWith
@@ -49,7 +49,7 @@ class ContextCacheConfigTest {
 
   @Test
   fun construct_customValues_exposesProperties() {
-    val httpOptions = HttpOptions(timeout = 10_000)
+    val httpOptions = HttpOptions(timeout = 10.seconds)
     val config =
       ContextCacheConfig(
         cacheIntervals = 5,

core/src/commonTest/kotlin/com/google/adk/kt/models/GeminiContextCacheManagerTest.kt

@@ -21,14 +21,15 @@ import com.google.adk.kt.agents.ContextCacheConfig
 import com.google.adk.kt.types.Content
 import com.google.adk.kt.types.FunctionCall
 import com.google.adk.kt.types.GenerateContentConfig
+import com.google.adk.kt.types.HttpOptions
 import com.google.adk.kt.types.Part
 import com.google.adk.kt.types.Role
 import com.google.adk.kt.types.ToolConfig
-import com.google.genai.kotlin.types.HttpOptions
 import kotlin.test.Test
 import kotlin.test.assertEquals
 import kotlin.test.assertNull
 import kotlin.time.Clock
+import kotlin.time.Duration.Companion.seconds
 import kotlinx.coroutines.test.runTest
 
 class GeminiContextCacheManagerTest {
@@ -202,7 +203,7 @@ class GeminiContextCacheManagerTest {
   fun handleContextCaching_createHttpOptionsConfigured_passedThroughToCreate() = runTest {
     val fake = FakeCacheClient(createdName = "cache/recreated")
     val manager = GeminiContextCacheManager("gemini-2.0-flash", fake)
-    val httpOptions = HttpOptions(timeout = 5_000)
+    val httpOptions = HttpOptions(timeout = 5.seconds)
     val request =
       baseRequest(tokenCount = 8000)
         .copy(cacheConfig = ContextCacheConfig(createHttpOptions = httpOptions))

examples/src/main/kotlin/com/google/adk/kt/examples/caching/ContextCachingDemoAgent.kt

@@ -27,8 +27,8 @@ import com.google.adk.kt.models.CacheMetadata
 import com.google.adk.kt.models.Gemini
 import com.google.adk.kt.runners.InMemoryRunner
 import com.google.adk.kt.types.Content
+import com.google.adk.kt.types.HttpOptions
 import com.google.adk.kt.types.Role
-import com.google.genai.kotlin.types.HttpOptions
 import kotlin.time.Duration.Companion.seconds
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.runBlocking
@@ -189,7 +189,7 @@ fun main() = runBlocking {
           minTokens = 0,
           // Fail open if cache creation is slow: cap it at 30s, after which the request proceeds
           // uncached instead of blocking on cache creation.
-          createHttpOptions = HttpOptions(timeout = 30_000),
+          createHttpOptions = HttpOptions(timeout = 30.seconds),
         ),
     )
   val runner = InMemoryRunner(app = app)