diff --git a/packages/core/src/session/compaction.ts b/packages/core/src/session/compaction.ts
index 5de1ef8dc1b..cac1089876a 100644
--- a/packages/core/src/session/compaction.ts
+++ b/packages/core/src/session/compaction.ts
@@ -32,7 +32,7 @@ import { SessionModelRequest } from "./model-request.js"
 import { SessionProviderContext } from "./provider-context.js"
 import { SessionRunnerRetry } from "./runner/retry.js"
 import { toLLMMessages } from "./runner/to-llm-message.js"
-import { toSessionError } from "./to-session-error.js"
+import { contentFilterError, toSessionError } from "./to-session-error.js"
 import { SessionUsage } from "./usage.js"
 
 export type Settings = {
@@ -540,10 +540,7 @@ export const layer = Layer.effect(
                   message: "Compaction summary reached the output token limit",
                 })
               case "content-filter":
-                return unusable({
-                  type: "provider.content-filter",
-                  message: "Compaction summary was blocked by the provider",
-                })
+                return unusable(contentFilterError("Compaction summary was blocked by the provider", event.reason))
               default:
                 return Effect.succeed(streamed)
             }
diff --git a/packages/core/src/session/runner/publish-llm-event.ts b/packages/core/src/session/runner/publish-llm-event.ts
index 988afb70b0e..bceffb61202 100644
--- a/packages/core/src/session/runner/publish-llm-event.ts
+++ b/packages/core/src/session/runner/publish-llm-event.ts
@@ -12,6 +12,7 @@ import { SessionSchema } from "../schema.js"
 import { SessionError } from "@opencode/schema/session-error"
 import { Money } from "@opencode/schema/money"
 import { SessionUsage } from "../usage.js"
+import { contentFilterError } from "../to-session-error.js"
 import type { Tool } from "../../tool.js"
 
 type Input = {
@@ -543,15 +544,7 @@ export const createLLMEventPublisher = (bus: Pick<Bus.Interface, "publish">, inp
         }
         if (event.reason.normalized === "content-filter") {
           providerFailed = true
-          yield* failAssistant({
-            type: "provider.content-filter",
-            message: [
-              `Provider blocked the response${event.reason.category === undefined ? "" : ` (${event.reason.category})`}`,
-              event.reason.explanation,
-            ]
-              .filter(Boolean)
-              .join(": "),
-          })
+          yield* failAssistant(contentFilterError("Provider blocked the response", event.reason))
           return
         }
         return
diff --git a/packages/core/src/session/to-session-error.ts b/packages/core/src/session/to-session-error.ts
index 46db0670389..d8eb0f683af 100644
--- a/packages/core/src/session/to-session-error.ts
+++ b/packages/core/src/session/to-session-error.ts
@@ -1,4 +1,4 @@
-import { AIError, ToolFailure } from "@opencode/ai"
+import { AIError, ToolFailure, type FinishReasonDetails } from "@opencode/ai"
 import { Tool } from "@opencode/schema/tool"
 import { SessionError } from "@opencode/schema/session-error"
 import { Permission } from "../permission.js"
@@ -85,6 +85,15 @@ export function toSessionError(cause: unknown): SessionError.Error {
   return { type: "unknown", message: cause instanceof Error ? cause.message : String(cause) }
 }
 
+export function contentFilterError(summary: string, reason: FinishReasonDetails): SessionError.Error {
+  return {
+    type: "provider.content-filter",
+    message: [reason.category === undefined ? summary : `${summary} (${reason.category})`, reason.explanation]
+      .filter(Boolean)
+      .join(": "),
+  }
+}
+
 function providerError(type: string, reason: AIError["reason"]): SessionError.Error {
   const status = reason.http?.status
   return {
diff --git a/packages/core/test/session-runner.test.ts b/packages/core/test/session-runner.test.ts
index ce6058c3720..68c8f3eb135 100644
--- a/packages/core/test/session-runner.test.ts
+++ b/packages/core/test/session-runner.test.ts
@@ -2716,6 +2716,32 @@ describe("SessionRunnerLLM", () => {
     )
   })
 
+  scenario("explains a compaction blocked by the provider", function* (s) {
+    yield* s.llm.push(TestLLM.text("Earlier answer", "history"))
+    yield* s.runPrompt("Earlier question")
+    yield* s.llm.push(
+      TestLLM.complete({
+        reason: {
+          normalized: "content-filter",
+          raw: "refusal",
+          category: "cyber",
+          explanation: "This request was declined because it could enable cyber harm.",
+        },
+      }),
+    )
+    const compaction = yield* s.session.compact({ sessionID })
+    yield* s.resume
+
+    expect((yield* s.messages).find((message) => message.id === compaction.id)).toMatchObject({
+      status: "failed",
+      error: {
+        type: "provider.content-filter",
+        message:
+          "Compaction summary was blocked by the provider (cyber): This request was declined because it could enable cyber harm.",
+      },
+    })
+  })
+
   for (const header of [false, true]) {
     scenario(`stops compaction retries through the ${header ? "provider header" : "retry hook"}`, function* (s) {
       yield* s.llm.push(TestLLM.text("Earlier answer", "history"))