diff --git a/package-lock.json b/package-lock.json
index 7aa3cfc4c..7ba661ca1 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -5280,12 +5280,12 @@
 		},
 		"packages/agent": {
 			"name": "@earendil-works/pi-agent-core",
-			"version": "0.86.1",
+			"version": "0.87.0",
 			"license": "MIT",
 			"dependencies": {
-				"@earendil-works/chord": "^0.86.1",
-				"@earendil-works/pi-ai": "^0.86.1",
-				"@earendil-works/pi-telemetry": "^0.86.1",
+				"@earendil-works/chord": "^0.87.0",
+				"@earendil-works/pi-ai": "^0.87.0",
+				"@earendil-works/pi-telemetry": "^0.87.0",
 				"diff": "8.0.4",
 				"ignore": "7.0.8",
 				"typebox": "1.3.27",
@@ -5310,12 +5310,12 @@
 		},
 		"packages/ai": {
 			"name": "@earendil-works/pi-ai",
-			"version": "0.86.1",
+			"version": "0.87.0",
 			"license": "MIT",
 			"dependencies": {
 				"@anthropic-ai/sdk": "0.124.0",
 				"@aws-sdk/client-bedrock-runtime": "3.1127.0",
-				"@earendil-works/pi-telemetry": "^0.86.1",
+				"@earendil-works/pi-telemetry": "^0.87.0",
 				"@google/genai": "2.21.0",
 				"@smithy/node-http-handler": "4.12.1",
 				"http-proxy-agent": "9.1.0",
@@ -5361,7 +5361,7 @@
 		},
 		"packages/chord": {
 			"name": "@earendil-works/chord",
-			"version": "0.86.1",
+			"version": "0.87.0",
 			"license": "MIT",
 			"dependencies": {
 				"esbuild": "0.28.2"
@@ -5376,11 +5376,11 @@
 		},
 		"packages/client": {
 			"name": "@earendil-works/pi-client",
-			"version": "0.86.1",
+			"version": "0.87.0",
 			"license": "MIT",
 			"dependencies": {
-				"@earendil-works/chord": "^0.86.1",
-				"@earendil-works/pi-protocol": "^0.86.1"
+				"@earendil-works/chord": "^0.87.0",
+				"@earendil-works/pi-protocol": "^0.87.0"
 			},
 			"devDependencies": {
 				"shx": "0.4.0",
@@ -5392,13 +5392,13 @@
 		},
 		"packages/coding-agent": {
 			"name": "@earendil-works/pi-coding-agent",
-			"version": "0.86.1",
+			"version": "0.87.0",
 			"license": "MIT",
 			"dependencies": {
-				"@earendil-works/chord": "^0.86.1",
-				"@earendil-works/pi-agent-core": "^0.86.1",
-				"@earendil-works/pi-ai": "^0.86.1",
-				"@earendil-works/pi-tui": "^0.86.1",
+				"@earendil-works/chord": "^0.87.0",
+				"@earendil-works/pi-agent-core": "^0.87.0",
+				"@earendil-works/pi-ai": "^0.87.0",
+				"@earendil-works/pi-tui": "^0.87.0",
 				"@silvia-odwyer/photon-node": "0.3.4",
 				"chalk": "6.0.0",
 				"cross-spawn": "7.0.6",
@@ -5419,9 +5419,9 @@
 				"pi": "dist/bundle/cli.js"
 			},
 			"devDependencies": {
-				"@earendil-works/pi-client": "^0.86.1",
-				"@earendil-works/pi-protocol": "^0.86.1",
-				"@earendil-works/pi-server": "^0.86.1",
+				"@earendil-works/pi-client": "^0.87.0",
+				"@earendil-works/pi-protocol": "^0.87.0",
+				"@earendil-works/pi-server": "^0.87.0",
 				"@types/cross-spawn": "6.0.6",
 				"@types/hosted-git-info": "3.0.5",
 				"@types/node": "22.19.19",
@@ -5438,32 +5438,32 @@
 		},
 		"packages/coding-agent/examples/extensions/custom-provider-anthropic": {
 			"name": "pi-extension-custom-provider-anthropic",
-			"version": "0.86.1",
+			"version": "0.87.0",
 			"dependencies": {
 				"@anthropic-ai/sdk": "0.52.0"
 			}
 		},
 		"packages/coding-agent/examples/extensions/custom-provider-gitlab-duo": {
 			"name": "pi-extension-custom-provider-gitlab-duo",
-			"version": "0.86.1"
+			"version": "0.87.0"
 		},
 		"packages/coding-agent/examples/extensions/gondolin": {
 			"name": "pi-extension-gondolin",
-			"version": "0.86.1",
+			"version": "0.87.0",
 			"dependencies": {
 				"@earendil-works/gondolin": "0.12.0"
 			}
 		},
 		"packages/coding-agent/examples/extensions/sandbox": {
 			"name": "pi-extension-sandbox",
-			"version": "1.16.1",
+			"version": "1.17.0",
 			"dependencies": {
 				"@anthropic-ai/sandbox-runtime": "0.0.26"
 			}
 		},
 		"packages/coding-agent/examples/extensions/with-deps": {
 			"name": "pi-extension-with-deps",
-			"version": "0.86.1",
+			"version": "0.87.0",
 			"dependencies": {
 				"ms": "2.1.3"
 			},
@@ -5517,11 +5517,11 @@
 		},
 		"packages/durable": {
 			"name": "@earendil-works/pi-durable",
-			"version": "0.86.1",
+			"version": "0.87.0",
 			"license": "MIT",
 			"dependencies": {
-				"@earendil-works/chord": "^0.86.1",
-				"@earendil-works/pi-ai": "^0.86.1"
+				"@earendil-works/chord": "^0.87.0",
+				"@earendil-works/pi-ai": "^0.87.0"
 			},
 			"devDependencies": {
 				"shx": "0.4.0",
@@ -5533,10 +5533,10 @@
 		},
 		"packages/evals": {
 			"name": "@earendil-works/pi-evals",
-			"version": "0.86.1",
+			"version": "0.87.0",
 			"devDependencies": {
-				"@earendil-works/pi-ai": "^0.86.1",
-				"@earendil-works/pi-coding-agent": "^0.86.1",
+				"@earendil-works/pi-ai": "^0.87.0",
+				"@earendil-works/pi-coding-agent": "^0.87.0",
 				"@types/node": "22.19.19",
 				"@vitest-evals/core": "0.15.0",
 				"autoevals": "0.3.0",
@@ -5548,10 +5548,10 @@
 		},
 		"packages/protocol": {
 			"name": "@earendil-works/pi-protocol",
-			"version": "0.86.1",
+			"version": "0.87.0",
 			"license": "MIT",
 			"dependencies": {
-				"@earendil-works/chord": "^0.86.1",
+				"@earendil-works/chord": "^0.87.0",
 				"typebox": "1.3.27"
 			},
 			"devDependencies": {
@@ -5564,12 +5564,12 @@
 		},
 		"packages/server": {
 			"name": "@earendil-works/pi-server",
-			"version": "0.86.1",
+			"version": "0.87.0",
 			"license": "MIT",
 			"dependencies": {
-				"@earendil-works/chord": "^0.86.1",
-				"@earendil-works/pi-agent-core": "^0.86.1",
-				"@earendil-works/pi-protocol": "^0.86.1"
+				"@earendil-works/chord": "^0.87.0",
+				"@earendil-works/pi-agent-core": "^0.87.0",
+				"@earendil-works/pi-protocol": "^0.87.0"
 			},
 			"devDependencies": {
 				"shx": "0.4.0",
@@ -5581,11 +5581,11 @@
 		},
 		"packages/session-backends/sqlite-node": {
 			"name": "@earendil-works/pi-session-backend-sqlite-node",
-			"version": "0.86.1",
+			"version": "0.87.0",
 			"license": "MIT",
 			"dependencies": {
-				"@earendil-works/pi-agent-core": "^0.86.1",
-				"@earendil-works/pi-ai": "^0.86.1"
+				"@earendil-works/pi-agent-core": "^0.87.0",
+				"@earendil-works/pi-ai": "^0.87.0"
 			},
 			"devDependencies": {
 				"@vitest/coverage-v8": "4.1.9",
@@ -5597,7 +5597,7 @@
 		},
 		"packages/telemetry": {
 			"name": "@earendil-works/pi-telemetry",
-			"version": "0.86.1",
+			"version": "0.87.0",
 			"license": "MIT",
 			"devDependencies": {
 				"@types/node": "22.19.19",
@@ -5609,7 +5609,7 @@
 		},
 		"packages/tui": {
 			"name": "@earendil-works/pi-tui",
-			"version": "0.86.1",
+			"version": "0.87.0",
 			"license": "MIT",
 			"dependencies": {
 				"get-east-asian-width": "1.6.0",
diff --git a/packages/agent/CHANGELOG.md b/packages/agent/CHANGELOG.md
index bb3e89b62..4393b17cd 100644
--- a/packages/agent/CHANGELOG.md
+++ b/packages/agent/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ## [Unreleased]
 
+## [0.87.0] - 2026-09-21
+
 ### Breaking Changes
 
 - Removed `AgentOptions.shouldStopAfterTurn` and `AgentLoopConfig.shouldStopAfterTurn`. Use `finishTurn` and return `{ action: "end" }` to stop after the completed turn:
diff --git a/packages/agent/package.json b/packages/agent/package.json
index 032092ad8..371ad64c5 100644
--- a/packages/agent/package.json
+++ b/packages/agent/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "@earendil-works/pi-agent-core",
-	"version": "0.86.1",
+	"version": "0.87.0",
 	"description": "General-purpose agent with transport abstraction, state management, and attachment support",
 	"type": "module",
 	"main": "./dist/index.js",
@@ -59,9 +59,9 @@
 		"prepublishOnly": "npm run build"
 	},
 	"dependencies": {
-		"@earendil-works/chord": "^0.86.1",
-		"@earendil-works/pi-ai": "^0.86.1",
-		"@earendil-works/pi-telemetry": "^0.86.1",
+		"@earendil-works/chord": "^0.87.0",
+		"@earendil-works/pi-ai": "^0.87.0",
+		"@earendil-works/pi-telemetry": "^0.87.0",
 		"diff": "8.0.4",
 		"ignore": "7.0.8",
 		"typebox": "1.3.27",
diff --git a/packages/ai/CHANGELOG.md b/packages/ai/CHANGELOG.md
index 1f96bd87e..4e1b21ead 100644
--- a/packages/ai/CHANGELOG.md
+++ b/packages/ai/CHANGELOG.md
@@ -4,6 +4,16 @@
 
 ### Added
 
+- Added Grok 4.7 to the built-in xAI model catalog with long-context pricing metadata.
+
+### Fixed
+
+- Fixed image-only user messages being rejected by some OpenAI-compatible providers because they included an empty text part ([#9797](https://github.com/earendil-works/pi/issues/9797))
+
+## [0.87.0] - 2026-09-21
+
+### Added
+
 - Added model image-input limit and cache-safe resize metadata to the generated catalog ([#9631](https://github.com/earendil-works/pi/issues/9631)).
 
 ### Fixed
diff --git a/packages/ai/README.md b/packages/ai/README.md
index 34237bd2b..7395672ff 100644
--- a/packages/ai/README.md
+++ b/packages/ai/README.md
@@ -833,7 +833,7 @@ Many models support thinking/reasoning capabilities where they can show their in
 const model = models.getModel('anthropic', 'claude-sonnet-4-5')!;
 // or models.getModel('openai', 'gpt-5-mini');
 // or models.getModel('google', 'gemini-2.5-flash');
-// or models.getModel('xai', 'grok-4.6');
+// or models.getModel('xai', 'grok-4.7');
 
 // Check if model supports reasoning
 if (model.reasoning) {
diff --git a/packages/ai/package.json b/packages/ai/package.json
index 111739b95..856f01197 100644
--- a/packages/ai/package.json
+++ b/packages/ai/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "@earendil-works/pi-ai",
-	"version": "0.86.1",
+	"version": "0.87.0",
 	"description": "Unified LLM API with automatic model discovery and provider configuration",
 	"type": "module",
 	"main": "./dist/index.js",
@@ -66,7 +66,7 @@
 	"dependencies": {
 		"@anthropic-ai/sdk": "0.124.0",
 		"@aws-sdk/client-bedrock-runtime": "3.1127.0",
-		"@earendil-works/pi-telemetry": "^0.86.1",
+		"@earendil-works/pi-telemetry": "^0.87.0",
 		"@google/genai": "2.21.0",
 		"@smithy/node-http-handler": "4.12.1",
 		"http-proxy-agent": "9.1.0",
diff --git a/packages/ai/scripts/generate-models.ts b/packages/ai/scripts/generate-models.ts
index ba4a49373..7b54f34d3 100644
--- a/packages/ai/scripts/generate-models.ts
+++ b/packages/ai/scripts/generate-models.ts
@@ -2030,12 +2030,7 @@ async function loadModelsDevData(): Promise<Model<any>[]> {
 					compat: { ...XAI_RESPONSES_COMPAT },
 					reasoning: m.reasoning === true,
 					input: m.modalities?.input?.includes("image") ? ["text", "image"] : ["text"],
-					cost: {
-						input: m.cost?.input || 0,
-						output: m.cost?.output || 0,
-						cacheRead: m.cost?.cache_read || 0,
-						cacheWrite: m.cost?.cache_write || 0,
-					},
+					cost: getModelsDevCost(m.cost),
 					contextWindow: m.limit?.context || 4096,
 					maxTokens: m.limit?.output || 4096,
 				});
diff --git a/packages/ai/src/api/openai-completions.ts b/packages/ai/src/api/openai-completions.ts
index 4ac0b6206..f5a1bc668 100644
--- a/packages/ai/src/api/openai-completions.ts
+++ b/packages/ai/src/api/openai-completions.ts
@@ -1257,21 +1257,23 @@ export function convertMessages(
 					content: sanitizeSurrogates(msg.content),
 				});
 			} else {
-				const content: ChatCompletionContentPart[] = msg.content.map((item): ChatCompletionContentPart => {
-					if (item.type === "text") {
-						return {
-							type: "text",
-							text: sanitizeSurrogates(item.text),
-						} satisfies ChatCompletionContentPartText;
-					} else {
-						return {
-							type: "image_url",
-							image_url: {
-								url: `data:${item.mimeType};base64,${item.data}`,
-							},
-						} satisfies ChatCompletionContentPartImage;
-					}
-				});
+				const content: ChatCompletionContentPart[] = msg.content
+					.filter((item) => item.type !== "text" || item.text.length > 0)
+					.map((item): ChatCompletionContentPart => {
+						if (item.type === "text") {
+							return {
+								type: "text",
+								text: sanitizeSurrogates(item.text),
+							} satisfies ChatCompletionContentPartText;
+						} else {
+							return {
+								type: "image_url",
+								image_url: {
+									url: `data:${item.mimeType};base64,${item.data}`,
+								},
+							} satisfies ChatCompletionContentPartImage;
+						}
+					});
 				if (content.length === 0) continue;
 				params.push({
 					role: "user",
diff --git a/packages/ai/test/model-catalog-types.test.ts b/packages/ai/test/model-catalog-types.test.ts
index 57f02e0f2..449764a93 100644
--- a/packages/ai/test/model-catalog-types.test.ts
+++ b/packages/ai/test/model-catalog-types.test.ts
@@ -8,6 +8,8 @@ it("derives model API, ID, and provider literals from grouped model data", () =>
 	expectTypeOf(XAI_MODELS["grok-4.5"].provider).toEqualTypeOf<"xai">();
 	expectTypeOf(XAI_MODELS["grok-4.6"].api).toEqualTypeOf<"openai-responses">();
 	expectTypeOf(XAI_MODELS["grok-4.6"].id).toEqualTypeOf<"grok-4.6">();
+	expectTypeOf(XAI_MODELS["grok-4.7"].api).toEqualTypeOf<"openai-responses">();
+	expectTypeOf(XAI_MODELS["grok-4.7"].id).toEqualTypeOf<"grok-4.7">();
 	expectTypeOf(XAI_MODELS["grok-4.3"].api).toEqualTypeOf<"openai-responses">();
 });
 
diff --git a/packages/ai/test/openai-completions-tool-result-images.test.ts b/packages/ai/test/openai-completions-tool-result-images.test.ts
index 6e48efe67..4d303865e 100644
--- a/packages/ai/test/openai-completions-tool-result-images.test.ts
+++ b/packages/ai/test/openai-completions-tool-result-images.test.ts
@@ -69,6 +69,35 @@ function buildEmptyToolResult(toolCallId: string, timestamp: number): ToolResult
 }
 
 describe("openai-completions convertMessages", () => {
+	// Regression test for https://github.com/earendil-works/pi/issues/9797
+	it("omits empty text parts from user messages with images", () => {
+		const { compat: _compat, ...baseModel } = getModel("openai", "gpt-4o-mini");
+		const model: Model<"openai-completions"> = {
+			...baseModel,
+			api: "openai-completions",
+			input: ["text", "image"],
+		};
+		const context = normalizeContext({
+			messages: [
+				{
+					role: "user",
+					content: [
+						{ type: "text", text: "" },
+						{ type: "image", data: "ZmFrZQ==", mimeType: "image/png" },
+					],
+					timestamp: Date.now(),
+				},
+			],
+		});
+
+		expect(convertMessages(model, context, compat)).toEqual([
+			{
+				role: "user",
+				content: [{ type: "image_url", image_url: { url: "data:image/png;base64,ZmFrZQ==" } }],
+			},
+		]);
+	});
+
 	it("batches tool-result images after consecutive tool results", () => {
 		const { compat: _compat, ...baseModel } = getModel("openai", "gpt-4o-mini");
 		const model: Model<"openai-completions"> = {
diff --git a/packages/ai/test/stream.test.ts b/packages/ai/test/stream.test.ts
index 362f30143..eb9afa226 100644
--- a/packages/ai/test/stream.test.ts
+++ b/packages/ai/test/stream.test.ts
@@ -540,8 +540,8 @@ describe("Generate E2E Tests", () => {
 		});
 	});
 
-	describe.skipIf(!process.env.XAI_API_KEY)("xAI Provider (grok-4.3 via OpenAI Responses)", () => {
-		const llm = getModel("xai", "grok-4.3");
+	describe.skipIf(!process.env.XAI_API_KEY)("xAI Provider (grok-4.7 via OpenAI Responses)", () => {
+		const llm = getModel("xai", "grok-4.7");
 
 		it("should complete basic text generation", { retry: 3 }, async () => {
 			await basicTextGeneration(llm);
diff --git a/packages/ai/test/xai-responses.test.ts b/packages/ai/test/xai-responses.test.ts
index d88c35a4d..1aa570177 100644
--- a/packages/ai/test/xai-responses.test.ts
+++ b/packages/ai/test/xai-responses.test.ts
@@ -132,9 +132,35 @@ describe("xAI Responses provider", () => {
 		}
 		expect(getSupportedThinkingLevels(XAI_MODELS["grok-4.5"])).toEqual(["low", "medium", "high"]);
 		expect(getSupportedThinkingLevels(XAI_MODELS["grok-4.6"])).toEqual(["low", "medium", "high", "xhigh"]);
+		expect(getSupportedThinkingLevels(XAI_MODELS["grok-4.7"])).toEqual(["low", "medium", "high", "xhigh"]);
 		expect(getSupportedThinkingLevels(XAI_MODELS["grok-4.3"])).toEqual(["off", "low", "medium", "high"]);
 	});
 
+	it("includes Grok 4.7 capabilities and long-context pricing", () => {
+		expect(XAI_MODELS["grok-4.7"]).toMatchObject({
+			api: "openai-responses",
+			reasoning: true,
+			input: ["text", "image"],
+			contextWindow: 500000,
+			maxTokens: 500000,
+			cost: {
+				input: 2,
+				output: 6,
+				cacheRead: 0.5,
+				cacheWrite: 0,
+				tiers: [
+					{
+						inputTokensAbove: 200000,
+						input: 4,
+						output: 12,
+						cacheRead: 1,
+						cacheWrite: 0,
+					},
+				],
+			},
+		});
+	});
+
 	it("uses /responses with bearer auth and xAI-compatible request fields", async () => {
 		const captured = await captureRequest(
 			XAI_MODELS["grok-4.5"],
@@ -188,9 +214,9 @@ describe("xAI Responses provider", () => {
 		expect(captured.body).not.toHaveProperty("reasoning");
 	});
 
-	it("uses /responses for Grok 4.6 with xhigh effort and encrypted reasoning", async () => {
+	it("uses /responses for Grok 4.7 with xhigh effort and encrypted reasoning", async () => {
 		const captured = await captureRequest(
-			XAI_MODELS["grok-4.6"],
+			XAI_MODELS["grok-4.7"],
 			{
 				systemPrompt: "You are a careful coding assistant.",
 				messages: [{ role: "user", content: "hello", timestamp: 1 }],
@@ -203,7 +229,7 @@ describe("xAI Responses provider", () => {
 
 		expect(captured.url).toBe("https://api.x.ai/v1/responses");
 		expect(captured.body).toMatchObject({
-			model: "grok-4.6",
+			model: "grok-4.7",
 			store: false,
 			stream: true,
 			reasoning: { effort: "xhigh" },
diff --git a/packages/chord/package.json b/packages/chord/package.json
index f7509c375..fa50e17e4 100644
--- a/packages/chord/package.json
+++ b/packages/chord/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "@earendil-works/chord",
-	"version": "0.86.1",
+	"version": "0.87.0",
 	"description": "Application composition runtime for services, replicated state, RPC, and plugins",
 	"type": "module",
 	"main": "./dist/index.js",
diff --git a/packages/client/CHANGELOG.md b/packages/client/CHANGELOG.md
index 86eb37b82..3c6e239b0 100644
--- a/packages/client/CHANGELOG.md
+++ b/packages/client/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ## [Unreleased]
 
+## [0.87.0] - 2026-09-21
+
 ## [0.86.1] - 2026-09-20
 
 ## [0.86.0] - 2026-09-19
diff --git a/packages/client/package.json b/packages/client/package.json
index d313018d0..673c364b8 100644
--- a/packages/client/package.json
+++ b/packages/client/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "@earendil-works/pi-client",
-	"version": "0.86.1",
+	"version": "0.87.0",
 	"description": "Transport-neutral client for remote pi sessions over framed CBOR bytes",
 	"type": "module",
 	"main": "./dist/index.js",
@@ -47,8 +47,8 @@
 		"node": ">=22.19.0"
 	},
 	"dependencies": {
-		"@earendil-works/chord": "^0.86.1",
-		"@earendil-works/pi-protocol": "^0.86.1"
+		"@earendil-works/chord": "^0.87.0",
+		"@earendil-works/pi-protocol": "^0.87.0"
 	},
 	"devDependencies": {
 		"shx": "0.4.0",
diff --git a/packages/coding-agent/CHANGELOG.md b/packages/coding-agent/CHANGELOG.md
index e16245f9e..cda0b2c65 100644
--- a/packages/coding-agent/CHANGELOG.md
+++ b/packages/coding-agent/CHANGELOG.md
@@ -2,8 +2,20 @@
 
 ## [Unreleased]
 
+### Changed
+
+- Changed the default xAI model to Grok 4.7.
+
+### Fixed
+
+- Fixed missing or invalid `--mode` values being silently ignored instead of reporting an error and exiting with a nonzero status ([#9045](https://github.com/earendil-works/pi/issues/9045)).
+
+## [0.87.0] - 2026-09-21
+
 ### New Features
 
+- **Canonical session context and extension boundaries** — Edit model context without rewriting history and add actionable lifecycle hooks. See [ContextEditEntry](docs/session-format.md#contexteditentry) and [extension events](docs/extensions.md#extension-events).
+- **Full-transcript context extensions** — Use `context_with_system` for per-request system-message transformations. See [`context_with_system`](docs/extensions.md#context_with_system).
 - **Per-model image input limits** — Configure cache-safe image resizing per model for attachments, `read`, and tool-result images. See [Image Input Limits](docs/models.md#image-input-limits).
 
 ### Breaking Changes
@@ -19,6 +31,7 @@
 - Added append-only model-context edits. For example, `sessionManager.appendContextEdit(entryId, null)` omits one message from future provider context without changing raw history, usage, or UI history.
 - Added actionable `turn_end` and `agent_before_settle` extension boundaries. Return `{ entries: [...event.entries, draft], continue: true }` to persist structural entries in order and ensure one next provider request without changing steering or follow-up scheduling.
 - Added retain-none compaction input: `sessionManager.appendCompaction(summary, null, tokensBefore)` stores the compaction's own ID as its kept boundary.
+- Added the `context_with_system` extension event, which runs after `context` handlers on the full transcript including system messages and sends its result verbatim. See [`context_with_system`](docs/extensions.md#context_with_system).
 - Added per-model image resize profiles through `inputLimits.images.resize` in `models.json`, applied to file attachments, image reads, and tool-result images ([#9631](https://github.com/earendil-works/pi/issues/9631)).
 
 ### Fixed
@@ -27,11 +40,12 @@
 - Fixed context-invisible boundary metadata and replacement edits causing newly appended or replaced input to be summarized before its first provider request.
 - Fixed edited-context accounting both discarding valid assistant usage captured after the latest context edit and reusing that usage after a later compaction made it stale.
 - Fixed selected error retries and final length/overflow recovery retaining abandoned model attempts in future provider context; post-run recovery omissions are now persisted without hiding raw transcript history or changing queue scheduling.
-- Fixed `/bug` allowing uploads in offline mode while preserving local zip exports.
+- Fixed `context` handlers that filter or slice messages dropping the prompt and tool declarations, which after extension-driven compaction left requests without built-in tools or made Codex emit raw tool-call text. Handlers no longer see system messages; Pi restores the prompt and tool state after they run. See [`context`](docs/extensions.md#context) ([#9789](https://github.com/earendil-works/pi/issues/9789), [#9822](https://github.com/earendil-works/pi/issues/9822)).
+- Fixed `/bug` allowing uploads in offline mode while preserving local zip exports ([#9841](https://github.com/earendil-works/pi/pull/9841) by [@christianklotz](https://github.com/christianklotz)).
 - Fixed idle prompt-cache warming rebuilding expired caches when its timer or an extension decision is delayed.
 - Improved crash diagnostics with hints identifying loaded extensions that appear in the stack trace.
 - Fixed text files beginning with `GIF` being misclassified as images and omitted from `read` and CLI `@file` input ([#9755](https://github.com/earendil-works/pi/issues/9755)).
-- Fixed malformed prompt template frontmatter being silently ignored instead of reported as a resource warning ([#9830](https://github.com/earendil-works/pi/pull/9830)).
+- Fixed malformed prompt template frontmatter being silently ignored instead of reported as a resource warning ([#9830](https://github.com/earendil-works/pi/pull/9830) by [@christianklotz](https://github.com/christianklotz)).
 - Fixed inherited unknown OpenAI-compatible Chat Completions endpoints receiving strict tool schemas unless they explicitly advertise support ([#9816](https://github.com/earendil-works/pi/issues/9816)).
 
 ## [0.86.1] - 2026-09-20
diff --git a/packages/coding-agent/docs/extensions.md b/packages/coding-agent/docs/extensions.md
index d58304c3b..89afa4863 100644
--- a/packages/coding-agent/docs/extensions.md
+++ b/packages/coding-agent/docs/extensions.md
@@ -294,7 +294,8 @@ user sends prompt ────────────────────
   │   ┌─── turn (repeats while LLM calls tools) ───┐       │
   │   │                                            │       │
   │   ├─► turn_start                               │       │
-  │   ├─► context (can modify messages)            │       │
+  │   ├─► context (can modify conversation messages)   │
+  │   ├─► context_with_system (can modify the full transcript)
   │   ├─► before_provider_headers (can mutate headers)     |
   │   ├─► before_provider_request (can inspect or replace payload)
   │   ├─► after_provider_response (status + headers, before stream consume)
@@ -725,12 +726,31 @@ Fired before each LLM call. Modify messages non-destructively. See [Session Form
 
 ```typescript
 pi.on("context", async (event, ctx) => {
-  // event.messages - deep copy, safe to modify
+  // event.messages - deep copy without system messages, safe to modify
   const filtered = event.messages.filter(m => !shouldPrune(m));
   return { messages: filtered };
 });
 ```
 
+`event.messages` holds the conversation without system messages. The prompt and tool declarations belong to Pi and are not part of this hook: when the handler returns a changed list, Pi replays the current prompt sections and tool declarations into one leading system message ahead of the returned messages. Filtering, windowing, or slicing from a compaction summary therefore cannot drop the prompt or the tools. An unchanged list keeps mid-conversation system messages in place, so models that accept them retain their cached prefix. System messages a handler adds are kept after Pi's head. To change the prompt or the tool set durably, use [`before_agent_start`](#before_agent_start) or `pi.setActiveTools()`; to edit system messages for one request, use [`context_with_system`](#context_with_system).
+
+#### context_with_system
+
+Fired before each LLM call, after every `context` handler has run and Pi has restored the prompt and tool state. `event.messages` is the full transcript, including the leading system message and any mid-conversation prompt or tool patches (see [Session Format](session-format.md#sessionmessageentry)). The returned messages are sent as they are: this hook owns the prompt and tool declarations for the request.
+
+```typescript
+import { getCurrentSystemMessage } from "@earendil-works/pi-ai";
+
+pi.on("context_with_system", async (event, ctx) => {
+  const cut = findCutIndex(event.messages);
+  // Fold the dropped prefix so its prompt and tool state survives as the new head.
+  const head = getCurrentSystemMessage(event.messages.slice(0, cut));
+  return { messages: head ? [head, ...event.messages.slice(cut)] : event.messages.slice(cut) };
+});
+```
+
+Rules: keep a system message at index 0 (providers read the prompt and initial tool declarations there; Pi reports an error if a handler drops it). Removing a system message removes the tool declarations and section patches it carries. Check your output with `getCurrentSystemPrompt()` and `getCurrentTools()` from `@earendil-works/pi-ai`. Handlers run in extension load order; a `systemPrompt` forced from `before_agent_start` is still projected onto the request afterwards.
+
 #### before_provider_headers
 
 Fired after the outgoing HTTP headers are assembled. Use it to add, override, or remove request headers.
diff --git a/packages/coding-agent/examples/extensions/custom-provider-anthropic/package-lock.json b/packages/coding-agent/examples/extensions/custom-provider-anthropic/package-lock.json
index 3eba4a83e..00832cb38 100644
--- a/packages/coding-agent/examples/extensions/custom-provider-anthropic/package-lock.json
+++ b/packages/coding-agent/examples/extensions/custom-provider-anthropic/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "pi-extension-custom-provider",
-  "version": "0.86.1",
+  "version": "0.87.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "pi-extension-custom-provider",
-      "version": "0.86.1",
+      "version": "0.87.0",
       "dependencies": {
         "@anthropic-ai/sdk": "^0.52.0"
       }
diff --git a/packages/coding-agent/examples/extensions/custom-provider-anthropic/package.json b/packages/coding-agent/examples/extensions/custom-provider-anthropic/package.json
index c0a973be7..5ade8ee7f 100644
--- a/packages/coding-agent/examples/extensions/custom-provider-anthropic/package.json
+++ b/packages/coding-agent/examples/extensions/custom-provider-anthropic/package.json
@@ -1,7 +1,7 @@
 {
   "name": "pi-extension-custom-provider-anthropic",
   "private": true,
-  "version": "0.86.1",
+  "version": "0.87.0",
   "type": "module",
   "scripts": {
     "clean": "echo 'nothing to clean'",
diff --git a/packages/coding-agent/examples/extensions/custom-provider-gitlab-duo/package.json b/packages/coding-agent/examples/extensions/custom-provider-gitlab-duo/package.json
index 3c4339b34..ef4c42601 100644
--- a/packages/coding-agent/examples/extensions/custom-provider-gitlab-duo/package.json
+++ b/packages/coding-agent/examples/extensions/custom-provider-gitlab-duo/package.json
@@ -1,7 +1,7 @@
 {
   "name": "pi-extension-custom-provider-gitlab-duo",
   "private": true,
-  "version": "0.86.1",
+  "version": "0.87.0",
   "type": "module",
   "scripts": {
     "clean": "echo 'nothing to clean'",
diff --git a/packages/coding-agent/examples/extensions/gondolin/package-lock.json b/packages/coding-agent/examples/extensions/gondolin/package-lock.json
index b71238fc2..5d7f6addf 100644
--- a/packages/coding-agent/examples/extensions/gondolin/package-lock.json
+++ b/packages/coding-agent/examples/extensions/gondolin/package-lock.json
@@ -1,12 +1,12 @@
 {
 	"name": "pi-extension-gondolin",
-	"version": "0.86.1",
+	"version": "0.87.0",
 	"lockfileVersion": 3,
 	"requires": true,
 	"packages": {
 		"": {
 			"name": "pi-extension-gondolin",
-			"version": "0.86.1",
+			"version": "0.87.0",
 			"dependencies": {
 				"@earendil-works/gondolin": "0.12.0"
 			}
diff --git a/packages/coding-agent/examples/extensions/gondolin/package.json b/packages/coding-agent/examples/extensions/gondolin/package.json
index df48e2aff..d692f0f8a 100644
--- a/packages/coding-agent/examples/extensions/gondolin/package.json
+++ b/packages/coding-agent/examples/extensions/gondolin/package.json
@@ -1,7 +1,7 @@
 {
 	"name": "pi-extension-gondolin",
 	"private": true,
-	"version": "0.86.1",
+	"version": "0.87.0",
 	"type": "module",
 	"scripts": {
 		"clean": "echo 'nothing to clean'",
diff --git a/packages/coding-agent/examples/extensions/sandbox/package-lock.json b/packages/coding-agent/examples/extensions/sandbox/package-lock.json
index bf3e01022..ac33d7af1 100644
--- a/packages/coding-agent/examples/extensions/sandbox/package-lock.json
+++ b/packages/coding-agent/examples/extensions/sandbox/package-lock.json
@@ -1,12 +1,12 @@
 {
 	"name": "pi-extension-sandbox",
-	"version": "1.16.1",
+	"version": "1.17.0",
 	"lockfileVersion": 3,
 	"requires": true,
 	"packages": {
 		"": {
 			"name": "pi-extension-sandbox",
-			"version": "1.16.1",
+			"version": "1.17.0",
 			"dependencies": {
 				"@anthropic-ai/sandbox-runtime": "^0.0.26"
 			}
diff --git a/packages/coding-agent/examples/extensions/sandbox/package.json b/packages/coding-agent/examples/extensions/sandbox/package.json
index 8847140cc..852d97a44 100644
--- a/packages/coding-agent/examples/extensions/sandbox/package.json
+++ b/packages/coding-agent/examples/extensions/sandbox/package.json
@@ -1,7 +1,7 @@
 {
 	"name": "pi-extension-sandbox",
 	"private": true,
-	"version": "1.16.1",
+	"version": "1.17.0",
 	"type": "module",
 	"scripts": {
 		"clean": "echo 'nothing to clean'",
diff --git a/packages/coding-agent/examples/extensions/with-deps/package-lock.json b/packages/coding-agent/examples/extensions/with-deps/package-lock.json
index c4811dd38..b5d8f1bd2 100644
--- a/packages/coding-agent/examples/extensions/with-deps/package-lock.json
+++ b/packages/coding-agent/examples/extensions/with-deps/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "pi-extension-with-deps",
-  "version": "0.86.1",
+  "version": "0.87.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "pi-extension-with-deps",
-      "version": "0.86.1",
+      "version": "0.87.0",
       "dependencies": {
         "ms": "^2.1.3"
       },
diff --git a/packages/coding-agent/examples/extensions/with-deps/package.json b/packages/coding-agent/examples/extensions/with-deps/package.json
index 41f636fe1..0d9f944c6 100644
--- a/packages/coding-agent/examples/extensions/with-deps/package.json
+++ b/packages/coding-agent/examples/extensions/with-deps/package.json
@@ -1,7 +1,7 @@
 {
   "name": "pi-extension-with-deps",
   "private": true,
-  "version": "0.86.1",
+  "version": "0.87.0",
   "type": "module",
   "scripts": {
     "clean": "echo 'nothing to clean'",
diff --git a/packages/coding-agent/install-lock/package-lock.json b/packages/coding-agent/install-lock/package-lock.json
index 5f4757662..aedadcb8a 100644
--- a/packages/coding-agent/install-lock/package-lock.json
+++ b/packages/coding-agent/install-lock/package-lock.json
@@ -1,14 +1,14 @@
 {
 	"name": "@earendil-works/pi-coding-agent-install",
-	"version": "0.86.1",
+	"version": "0.87.0",
 	"lockfileVersion": 3,
 	"requires": true,
 	"packages": {
 		"": {
 			"name": "@earendil-works/pi-coding-agent-install",
-			"version": "0.86.1",
+			"version": "0.87.0",
 			"dependencies": {
-				"@earendil-works/pi-coding-agent": "0.86.1"
+				"@earendil-works/pi-coding-agent": "0.87.0"
 			},
 			"engines": {
 				"node": ">=22.19.0"
@@ -386,8 +386,8 @@
 			}
 		},
 		"node_modules/@earendil-works/chord": {
-			"version": "0.86.1",
-			"resolved": "https://registry.npmjs.org/@earendil-works/chord/-/chord-0.86.1.tgz",
+			"version": "0.87.0",
+			"resolved": "https://registry.npmjs.org/@earendil-works/chord/-/chord-0.87.0.tgz",
 			"license": "MIT",
 			"dependencies": {
 				"esbuild": "0.28.2"
@@ -397,13 +397,13 @@
 			}
 		},
 		"node_modules/@earendil-works/pi-agent-core": {
-			"version": "0.86.1",
-			"resolved": "https://registry.npmjs.org/@earendil-works/pi-agent-core/-/pi-agent-core-0.86.1.tgz",
+			"version": "0.87.0",
+			"resolved": "https://registry.npmjs.org/@earendil-works/pi-agent-core/-/pi-agent-core-0.87.0.tgz",
 			"license": "MIT",
 			"dependencies": {
-				"@earendil-works/chord": "^0.86.1",
-				"@earendil-works/pi-ai": "^0.86.1",
-				"@earendil-works/pi-telemetry": "^0.86.1",
+				"@earendil-works/chord": "^0.87.0",
+				"@earendil-works/pi-ai": "^0.87.0",
+				"@earendil-works/pi-telemetry": "^0.87.0",
 				"diff": "8.0.4",
 				"ignore": "7.0.8",
 				"typebox": "1.3.27",
@@ -414,13 +414,13 @@
 			}
 		},
 		"node_modules/@earendil-works/pi-ai": {
-			"version": "0.86.1",
-			"resolved": "https://registry.npmjs.org/@earendil-works/pi-ai/-/pi-ai-0.86.1.tgz",
+			"version": "0.87.0",
+			"resolved": "https://registry.npmjs.org/@earendil-works/pi-ai/-/pi-ai-0.87.0.tgz",
 			"license": "MIT",
 			"dependencies": {
 				"@anthropic-ai/sdk": "0.124.0",
 				"@aws-sdk/client-bedrock-runtime": "3.1127.0",
-				"@earendil-works/pi-telemetry": "^0.86.1",
+				"@earendil-works/pi-telemetry": "^0.87.0",
 				"@google/genai": "2.21.0",
 				"@smithy/node-http-handler": "4.12.1",
 				"http-proxy-agent": "9.1.0",
@@ -460,14 +460,14 @@
 			}
 		},
 		"node_modules/@earendil-works/pi-coding-agent": {
-			"version": "0.86.1",
-			"resolved": "https://registry.npmjs.org/@earendil-works/pi-coding-agent/-/pi-coding-agent-0.86.1.tgz",
+			"version": "0.87.0",
+			"resolved": "https://registry.npmjs.org/@earendil-works/pi-coding-agent/-/pi-coding-agent-0.87.0.tgz",
 			"license": "MIT",
 			"dependencies": {
-				"@earendil-works/chord": "^0.86.1",
-				"@earendil-works/pi-agent-core": "^0.86.1",
-				"@earendil-works/pi-ai": "^0.86.1",
-				"@earendil-works/pi-tui": "^0.86.1",
+				"@earendil-works/chord": "^0.87.0",
+				"@earendil-works/pi-agent-core": "^0.87.0",
+				"@earendil-works/pi-ai": "^0.87.0",
+				"@earendil-works/pi-tui": "^0.87.0",
 				"@silvia-odwyer/photon-node": "0.3.4",
 				"chalk": "6.0.0",
 				"cross-spawn": "7.0.6",
@@ -492,16 +492,16 @@
 			}
 		},
 		"node_modules/@earendil-works/pi-telemetry": {
-			"version": "0.86.1",
-			"resolved": "https://registry.npmjs.org/@earendil-works/pi-telemetry/-/pi-telemetry-0.86.1.tgz",
+			"version": "0.87.0",
+			"resolved": "https://registry.npmjs.org/@earendil-works/pi-telemetry/-/pi-telemetry-0.87.0.tgz",
 			"license": "MIT",
 			"engines": {
 				"node": ">=22.19.0"
 			}
 		},
 		"node_modules/@earendil-works/pi-tui": {
-			"version": "0.86.1",
-			"resolved": "https://registry.npmjs.org/@earendil-works/pi-tui/-/pi-tui-0.86.1.tgz",
+			"version": "0.87.0",
+			"resolved": "https://registry.npmjs.org/@earendil-works/pi-tui/-/pi-tui-0.87.0.tgz",
 			"license": "MIT",
 			"dependencies": {
 				"get-east-asian-width": "1.6.0",
diff --git a/packages/coding-agent/install-lock/package.json b/packages/coding-agent/install-lock/package.json
index 810b8d2bf..6f2e26c58 100644
--- a/packages/coding-agent/install-lock/package.json
+++ b/packages/coding-agent/install-lock/package.json
@@ -1,10 +1,10 @@
 {
 	"name": "@earendil-works/pi-coding-agent-install",
-	"version": "0.86.1",
+	"version": "0.87.0",
 	"private": true,
 	"description": "Lockfile root used by the Pi installer and updater.",
 	"dependencies": {
-		"@earendil-works/pi-coding-agent": "0.86.1"
+		"@earendil-works/pi-coding-agent": "0.87.0"
 	},
 	"overrides": {
 		"protobufjs": "7.6.6"
diff --git a/packages/coding-agent/npm-shrinkwrap.json b/packages/coding-agent/npm-shrinkwrap.json
index 4a82f9cd1..11743c285 100644
--- a/packages/coding-agent/npm-shrinkwrap.json
+++ b/packages/coding-agent/npm-shrinkwrap.json
@@ -1,18 +1,18 @@
 {
 	"name": "@earendil-works/pi-coding-agent",
-	"version": "0.86.1",
+	"version": "0.87.0",
 	"lockfileVersion": 3,
 	"requires": true,
 	"packages": {
 		"": {
 			"name": "@earendil-works/pi-coding-agent",
-			"version": "0.86.1",
+			"version": "0.87.0",
 			"license": "MIT",
 			"dependencies": {
-				"@earendil-works/chord": "^0.86.1",
-				"@earendil-works/pi-agent-core": "^0.86.1",
-				"@earendil-works/pi-ai": "^0.86.1",
-				"@earendil-works/pi-tui": "^0.86.1",
+				"@earendil-works/chord": "^0.87.0",
+				"@earendil-works/pi-agent-core": "^0.87.0",
+				"@earendil-works/pi-ai": "^0.87.0",
+				"@earendil-works/pi-tui": "^0.87.0",
 				"@silvia-odwyer/photon-node": "0.3.4",
 				"chalk": "6.0.0",
 				"cross-spawn": "7.0.6",
@@ -408,8 +408,8 @@
 			}
 		},
 		"node_modules/@earendil-works/chord": {
-			"version": "0.86.1",
-			"resolved": "https://registry.npmjs.org/@earendil-works/chord/-/chord-0.86.1.tgz",
+			"version": "0.87.0",
+			"resolved": "https://registry.npmjs.org/@earendil-works/chord/-/chord-0.87.0.tgz",
 			"license": "MIT",
 			"dependencies": {
 				"esbuild": "0.28.2"
@@ -419,13 +419,13 @@
 			}
 		},
 		"node_modules/@earendil-works/pi-agent-core": {
-			"version": "0.86.1",
-			"resolved": "https://registry.npmjs.org/@earendil-works/pi-agent-core/-/pi-agent-core-0.86.1.tgz",
+			"version": "0.87.0",
+			"resolved": "https://registry.npmjs.org/@earendil-works/pi-agent-core/-/pi-agent-core-0.87.0.tgz",
 			"license": "MIT",
 			"dependencies": {
-				"@earendil-works/chord": "^0.86.1",
-				"@earendil-works/pi-ai": "^0.86.1",
-				"@earendil-works/pi-telemetry": "^0.86.1",
+				"@earendil-works/chord": "^0.87.0",
+				"@earendil-works/pi-ai": "^0.87.0",
+				"@earendil-works/pi-telemetry": "^0.87.0",
 				"diff": "8.0.4",
 				"ignore": "7.0.8",
 				"typebox": "1.3.27",
@@ -436,13 +436,13 @@
 			}
 		},
 		"node_modules/@earendil-works/pi-ai": {
-			"version": "0.86.1",
-			"resolved": "https://registry.npmjs.org/@earendil-works/pi-ai/-/pi-ai-0.86.1.tgz",
+			"version": "0.87.0",
+			"resolved": "https://registry.npmjs.org/@earendil-works/pi-ai/-/pi-ai-0.87.0.tgz",
 			"license": "MIT",
 			"dependencies": {
 				"@anthropic-ai/sdk": "0.124.0",
 				"@aws-sdk/client-bedrock-runtime": "3.1127.0",
-				"@earendil-works/pi-telemetry": "^0.86.1",
+				"@earendil-works/pi-telemetry": "^0.87.0",
 				"@google/genai": "2.21.0",
 				"@smithy/node-http-handler": "4.12.1",
 				"http-proxy-agent": "9.1.0",
@@ -482,16 +482,16 @@
 			}
 		},
 		"node_modules/@earendil-works/pi-telemetry": {
-			"version": "0.86.1",
-			"resolved": "https://registry.npmjs.org/@earendil-works/pi-telemetry/-/pi-telemetry-0.86.1.tgz",
+			"version": "0.87.0",
+			"resolved": "https://registry.npmjs.org/@earendil-works/pi-telemetry/-/pi-telemetry-0.87.0.tgz",
 			"license": "MIT",
 			"engines": {
 				"node": ">=22.19.0"
 			}
 		},
 		"node_modules/@earendil-works/pi-tui": {
-			"version": "0.86.1",
-			"resolved": "https://registry.npmjs.org/@earendil-works/pi-tui/-/pi-tui-0.86.1.tgz",
+			"version": "0.87.0",
+			"resolved": "https://registry.npmjs.org/@earendil-works/pi-tui/-/pi-tui-0.87.0.tgz",
 			"license": "MIT",
 			"dependencies": {
 				"get-east-asian-width": "1.6.0",
diff --git a/packages/coding-agent/package.json b/packages/coding-agent/package.json
index d1b6634ff..eae863020 100644
--- a/packages/coding-agent/package.json
+++ b/packages/coding-agent/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "@earendil-works/pi-coding-agent",
-	"version": "0.86.1",
+	"version": "0.87.0",
 	"description": "Coding agent CLI with read, bash, edit, write tools and session management",
 	"type": "module",
 	"piConfig": {
@@ -49,10 +49,10 @@
 		"prepublishOnly": "npm run clean && npm run build && npm run shrinkwrap"
 	},
 	"dependencies": {
-		"@earendil-works/chord": "^0.86.1",
-		"@earendil-works/pi-agent-core": "^0.86.1",
-		"@earendil-works/pi-ai": "^0.86.1",
-		"@earendil-works/pi-tui": "^0.86.1",
+		"@earendil-works/chord": "^0.87.0",
+		"@earendil-works/pi-agent-core": "^0.87.0",
+		"@earendil-works/pi-ai": "^0.87.0",
+		"@earendil-works/pi-tui": "^0.87.0",
 		"@silvia-odwyer/photon-node": "0.3.4",
 		"chalk": "6.0.0",
 		"cross-spawn": "7.0.6",
@@ -73,9 +73,9 @@
 		"protobufjs": "7.6.6"
 	},
 	"devDependencies": {
-		"@earendil-works/pi-client": "^0.86.1",
-		"@earendil-works/pi-protocol": "^0.86.1",
-		"@earendil-works/pi-server": "^0.86.1",
+		"@earendil-works/pi-client": "^0.87.0",
+		"@earendil-works/pi-protocol": "^0.87.0",
+		"@earendil-works/pi-server": "^0.87.0",
 		"@types/cross-spawn": "6.0.6",
 		"@types/hosted-git-info": "3.0.5",
 		"@types/node": "22.19.19",
diff --git a/packages/coding-agent/src/cli/args.ts b/packages/coding-agent/src/cli/args.ts
index 284888d13..a35879807 100644
--- a/packages/coding-agent/src/cli/args.ts
+++ b/packages/coding-agent/src/cli/args.ts
@@ -92,11 +92,21 @@ export function parseArgs(args: string[]): Args {
 			result.help = true;
 		} else if (arg === "--version" || arg === "-v") {
 			result.version = true;
-		} else if (arg === "--mode" && i + 1 < args.length) {
-			const mode = args[++i];
-			if (mode === "text" || mode === "json" || mode === "rpc") {
-				result.mode = mode;
+		} else if (arg === "--mode") {
+			const mode = args[i + 1];
+			if (mode === undefined || mode.startsWith("-")) {
+				result.diagnostics.push({ type: "error", message: "--mode requires text, json, or rpc" });
+				continue;
 			}
+			i++;
+			if (mode !== "text" && mode !== "json" && mode !== "rpc") {
+				result.diagnostics.push({
+					type: "error",
+					message: `Invalid mode "${mode}". Valid values: text, json, rpc`,
+				});
+				continue;
+			}
+			result.mode = mode;
 		} else if (arg === "--continue" || arg === "-c") {
 			result.continue = true;
 		} else if (arg === "--resume" || arg === "-r") {
diff --git a/packages/coding-agent/src/core/extensions/index.ts b/packages/coding-agent/src/core/extensions/index.ts
index 57b2e77bf..ad0287629 100644
--- a/packages/coding-agent/src/core/extensions/index.ts
+++ b/packages/coding-agent/src/core/extensions/index.ts
@@ -57,6 +57,7 @@ export type {
 	// Event Results
 	ContextEventResult,
 	ContextUsage,
+	ContextWithSystemEvent,
 	CustomEntryDraft,
 	CustomMessageEntryDraft,
 	CustomToolCallEvent,
diff --git a/packages/coding-agent/src/core/extensions/runner.ts b/packages/coding-agent/src/core/extensions/runner.ts
index 44576a1bb..b0e99f8ff 100644
--- a/packages/coding-agent/src/core/extensions/runner.ts
+++ b/packages/coding-agent/src/core/extensions/runner.ts
@@ -3,7 +3,13 @@
  */
 
 import type { AgentMessage } from "@earendil-works/pi-agent-core";
-import type { ImageContent, Model, Provider, ProviderHeaders } from "@earendil-works/pi-ai";
+import {
+	getCurrentSystemMessage,
+	type ImageContent,
+	type Model,
+	type Provider,
+	type ProviderHeaders,
+} from "@earendil-works/pi-ai";
 import type { KeyId } from "@earendil-works/pi-tui";
 import { type Theme, theme } from "../../modes/interactive/theme/theme.ts";
 import type { CacheWarmingAction } from "../cache-warmer.ts";
@@ -32,6 +38,7 @@ import type {
 	ContextEvent,
 	ContextEventResult,
 	ContextUsage,
+	ContextWithSystemEvent,
 	EntryRenderer,
 	Extension,
 	ExtensionActions,
@@ -169,6 +176,7 @@ type RunnerEmitEvent = Exclude<
 	| ToolResultEvent
 	| UserBashEvent
 	| ContextEvent
+	| ContextWithSystemEvent
 	| CacheWarmingDecisionEvent
 	| BeforeProviderRequestEvent
 	| BeforeProviderHeadersEvent
@@ -258,6 +266,28 @@ function snapshotEventHandlers(extensions: Extension[], event: ExtensionEvent["t
 	return extensions.map((ext) => ({ ext, handlers: ext.handlers.get(event)?.slice() ?? [] }));
 }
 
+function sameMessages(left: AgentMessage[], right: AgentMessage[]): boolean {
+	return left.length === right.length && left.every((message, index) => message === right[index]);
+}
+
+/**
+ * Re-attach the prompt and tool state after a `context` handler. Handlers only see the
+ * conversation; the system messages belong to Pi. An unchanged conversation keeps every
+ * system message in place, so models with mid-conversation support keep their cached
+ * prefix. A changed one gets the replayed prompt sections and tool declarations as one
+ * leading system message, so pruning, windowing, or slicing from a compaction summary
+ * cannot drop them.
+ */
+function restoreSystemMessages(
+	current: AgentMessage[],
+	visible: AgentMessage[],
+	returned: AgentMessage[],
+): AgentMessage[] {
+	if (sameMessages(returned, visible)) return current;
+	const head = getCurrentSystemMessage(current);
+	return head ? [head, ...returned] : returned;
+}
+
 export async function emitProjectTrustEvent(
 	extensionsResult: LoadExtensionsResult,
 	event: ProjectTrustEvent,
@@ -1152,6 +1182,11 @@ export class ExtensionRunner {
 		return undefined;
 	}
 
+	/**
+	 * Run the request-time transforms in two phases. `context` handlers see the conversation
+	 * only and Pi restores the prompt and tool state after each; `context_with_system`
+	 * handlers then see the full transcript and their output is used as returned.
+	 */
 	async emitContext(messages: AgentMessage[]): Promise<AgentMessage[]> {
 		const ctx = this.createContext();
 		let currentMessages = structuredClone(messages);
@@ -1159,12 +1194,17 @@ export class ExtensionRunner {
 		for (const { ext, handlers } of snapshotEventHandlers(this.extensions, "context")) {
 			for (const handler of handlers) {
 				try {
-					const event: ContextEvent = { type: "context", messages: currentMessages };
-					const handlerResult = await handler(event, ctx);
+					const visibleMessages = currentMessages.filter((message) => message.role !== "system");
+					const visibleSnapshot = visibleMessages.slice();
+					const event: ContextEvent = { type: "context", messages: visibleMessages };
+					const handlerResult = (await handler(event, ctx)) as ContextEventResult | undefined;
 
-					if (handlerResult && (handlerResult as ContextEventResult).messages) {
-						currentMessages = (handlerResult as ContextEventResult).messages!;
-					}
+					// Handlers may return a new list or edit event.messages in place.
+					const returned =
+						handlerResult?.messages ??
+						(sameMessages(visibleMessages, visibleSnapshot) ? undefined : visibleMessages);
+					if (!returned) continue;
+					currentMessages = restoreSystemMessages(currentMessages, visibleSnapshot, returned);
 				} catch (err) {
 					const message = err instanceof Error ? err.message : String(err);
 					const stack = err instanceof Error ? err.stack : undefined;
@@ -1178,6 +1218,35 @@ export class ExtensionRunner {
 			}
 		}
 
+		for (const { ext, handlers } of snapshotEventHandlers(this.extensions, "context_with_system")) {
+			for (const handler of handlers) {
+				try {
+					const hadLeadingSystemMessage = currentMessages[0]?.role === "system";
+					const event: ContextWithSystemEvent = { type: "context_with_system", messages: currentMessages };
+					const handlerResult = (await handler(event, ctx)) as ContextEventResult | undefined;
+					currentMessages = handlerResult?.messages ?? currentMessages;
+					// Providers read the prompt and initial tools from the leading system message.
+					// Losing it is never intended; report it but honor the handler's output.
+					if (hadLeadingSystemMessage && currentMessages[0]?.role !== "system") {
+						this.emitError({
+							extensionPath: ext.path,
+							event: "context_with_system",
+							error: "Handler removed the leading system message; the request has no prompt or initial tool declarations. Keep it at index 0 or replace a dropped prefix with getCurrentSystemMessage().",
+						});
+					}
+				} catch (err) {
+					const message = err instanceof Error ? err.message : String(err);
+					const stack = err instanceof Error ? err.stack : undefined;
+					this.emitError({
+						extensionPath: ext.path,
+						event: "context_with_system",
+						error: message,
+						stack,
+					});
+				}
+			}
+		}
+
 		return currentMessages;
 	}
 
diff --git a/packages/coding-agent/src/core/extensions/types.ts b/packages/coding-agent/src/core/extensions/types.ts
index d10078701..41bc4e672 100644
--- a/packages/coding-agent/src/core/extensions/types.ts
+++ b/packages/coding-agent/src/core/extensions/types.ts
@@ -688,12 +688,28 @@ export type SessionEvent =
 // Agent Events
 // ============================================================================
 
-/** Fired before each LLM call. Can modify messages. */
+/**
+ * Fired before each LLM call. Can modify messages.
+ *
+ * `messages` holds the conversation without system messages. The prompt and tool state
+ * belong to Pi: it restores them after the handler returns, so a handler cannot drop
+ * them and does not need to preserve them.
+ */
 export interface ContextEvent {
 	type: "context";
 	messages: AgentMessage[];
 }
 
+/**
+ * Fired before each LLM call, after every `context` handler has run and Pi has restored
+ * the prompt and tool state. `messages` is the full transcript including system messages,
+ * and the result is sent as returned: the handler owns the prompt and tool declarations.
+ */
+export interface ContextWithSystemEvent {
+	type: "context_with_system";
+	messages: AgentMessage[];
+}
+
 /** Fired before a provider request is sent. Can replace the payload. */
 export interface BeforeProviderRequestEvent {
 	type: "before_provider_request";
@@ -1156,6 +1172,7 @@ export type ExtensionEvent =
 	| ResourcesDiscoverEvent
 	| SessionEvent
 	| ContextEvent
+	| ContextWithSystemEvent
 	| CacheWarmingDecisionEvent
 	| BeforeProviderRequestEvent
 	| BeforeProviderHeadersEvent
@@ -1362,6 +1379,7 @@ export interface ExtensionAPI {
 	): () => void;
 	on(event: "session_tree", handler: ExtensionHandler<SessionTreeEvent>): () => void;
 	on(event: "context", handler: ExtensionHandler<ContextEvent, ContextEventResult>): () => void;
+	on(event: "context_with_system", handler: ExtensionHandler<ContextWithSystemEvent, ContextEventResult>): () => void;
 	on(
 		event: "cache_warming_decision",
 		handler: ExtensionHandler<CacheWarmingDecisionEvent, CacheWarmingDecisionEventResult>,
diff --git a/packages/coding-agent/src/core/index.ts b/packages/coding-agent/src/core/index.ts
index 178ed7105..fe82f5691 100644
--- a/packages/coding-agent/src/core/index.ts
+++ b/packages/coding-agent/src/core/index.ts
@@ -51,6 +51,7 @@ export {
 	type CompactionEntryDraft,
 	type ContextEditEntryDraft,
 	type ContextEvent,
+	type ContextWithSystemEvent,
 	type CustomEntryDraft,
 	type CustomMessageEntryDraft,
 	defineTool,
diff --git a/packages/coding-agent/src/core/model-resolver.ts b/packages/coding-agent/src/core/model-resolver.ts
index 64aa93608..44f22ad8f 100644
--- a/packages/coding-agent/src/core/model-resolver.ts
+++ b/packages/coding-agent/src/core/model-resolver.ts
@@ -32,7 +32,7 @@ export const defaultModelPerProvider: Record<KnownProvider, string> = {
 	"github-copilot": "gpt-5.4",
 	openrouter: "moonshotai/kimi-k2.6",
 	"vercel-ai-gateway": "zai/glm-5.1",
-	xai: "grok-4.6",
+	xai: "grok-4.7",
 	groq: "openai/gpt-oss-120b",
 	cerebras: "gpt-oss-120b",
 	zai: "glm-5.3",
diff --git a/packages/coding-agent/src/index.ts b/packages/coding-agent/src/index.ts
index 86907ebba..8746a894b 100644
--- a/packages/coding-agent/src/index.ts
+++ b/packages/coding-agent/src/index.ts
@@ -81,6 +81,7 @@ export type {
 	ContextEvent,
 	ContextEventResult,
 	ContextUsage,
+	ContextWithSystemEvent,
 	CustomEntryDraft,
 	CustomMessageEntryDraft,
 	CustomToolCallEvent,
diff --git a/packages/coding-agent/test/agent-session-concurrent.test.ts b/packages/coding-agent/test/agent-session-concurrent.test.ts
index 0df97e0d9..1fb8b4517 100644
--- a/packages/coding-agent/test/agent-session-concurrent.test.ts
+++ b/packages/coding-agent/test/agent-session-concurrent.test.ts
@@ -632,6 +632,7 @@ describe("AgentSession concurrent prompt guard", () => {
 			"user",
 			"assistant",
 			"toolResult",
+			"system",
 			"assistant",
 		]);
 	});
diff --git a/packages/coding-agent/test/args.test.ts b/packages/coding-agent/test/args.test.ts
index 710ed7b09..37e6407d5 100644
--- a/packages/coding-agent/test/args.test.ts
+++ b/packages/coding-agent/test/args.test.ts
@@ -115,16 +115,6 @@ describe("parseArgs", () => {
 			expect(result.appendSystemPrompt).toEqual(["Context A", "Context B"]);
 		});
 
-		test("parses --mode", () => {
-			const result = parseArgs(["--mode", "json"]);
-			expect(result.mode).toBe("json");
-		});
-
-		test("parses --mode rpc", () => {
-			const result = parseArgs(["--mode", "rpc"]);
-			expect(result.mode).toBe("rpc");
-		});
-
 		test("parses --session", () => {
 			const result = parseArgs(["--session", "/path/to/session.jsonl"]);
 			expect(result.session).toBe("/path/to/session.jsonl");
@@ -157,6 +147,48 @@ describe("parseArgs", () => {
 		});
 	});
 
+	// Issue #9045
+	describe("--mode flag", () => {
+		test.each(["text", "json", "rpc"] as const)("parses --mode %s", (mode) => {
+			const result = parseArgs(["--mode", mode]);
+			expect(result.mode).toBe(mode);
+			expect(result.diagnostics).toEqual([]);
+		});
+
+		test.each(["yaml", ""])("rejects invalid --mode value %j", (mode) => {
+			const result = parseArgs(["--mode", mode, "--version"]);
+			expect(result.mode).toBeUndefined();
+			expect(result.version).toBe(true);
+			expect(result.messages).toEqual([]);
+			expect(result.unknownFlags.size).toBe(0);
+			expect(result.diagnostics).toEqual([
+				{ type: "error", message: `Invalid mode "${mode}". Valid values: text, json, rpc` },
+			]);
+		});
+
+		test("reports a missing --mode value", () => {
+			const result = parseArgs(["--mode"]);
+			expect(result.mode).toBeUndefined();
+			expect(result.unknownFlags.size).toBe(0);
+			expect(result.diagnostics).toEqual([{ type: "error", message: "--mode requires text, json, or rpc" }]);
+		});
+
+		test("does not consume another option as a --mode value", () => {
+			const result = parseArgs(["--mode", "--version"]);
+			expect(result.mode).toBeUndefined();
+			expect(result.version).toBe(true);
+			expect(result.unknownFlags.size).toBe(0);
+			expect(result.diagnostics).toEqual([{ type: "error", message: "--mode requires text, json, or rpc" }]);
+		});
+
+		test("reports an invalid --mode value after a valid one", () => {
+			const result = parseArgs(["--mode", "json", "--mode", "yaml"]);
+			expect(result.diagnostics).toEqual([
+				{ type: "error", message: 'Invalid mode "yaml". Valid values: text, json, rpc' },
+			]);
+		});
+	});
+
 	describe("--name flag", () => {
 		test("parses --name flag with value", () => {
 			const result = parseArgs(["--name", "my-session"]);
diff --git a/packages/coding-agent/test/model-registry.test.ts b/packages/coding-agent/test/model-registry.test.ts
index 17ba7a182..ccf925f09 100644
--- a/packages/coding-agent/test/model-registry.test.ts
+++ b/packages/coding-agent/test/model-registry.test.ts
@@ -704,7 +704,7 @@ describe("ModelRegistry", () => {
 			expect(sonnet?.name).toBe("Custom Sonnet Name");
 
 			// Other models should be unchanged
-			const opus = models.find((m) => m.id === "anthropic/claude-opus-4");
+			const opus = models.find((m) => m.id === "anthropic/claude-opus-4.1");
 			expect(opus?.name).not.toBe("Custom Sonnet Name");
 		});
 
@@ -783,7 +783,7 @@ describe("ModelRegistry", () => {
 			expect(sonnet?.samplingParams).toEqual({ top_p: 0.9 });
 
 			// Models without sampling config keep it unset.
-			const opus = models.find((m) => m.id === "anthropic/claude-opus-4");
+			const opus = models.find((m) => m.id === "anthropic/claude-opus-4.1");
 			expect(opus?.samplingParams).toBeUndefined();
 		});
 
@@ -810,7 +810,7 @@ describe("ModelRegistry", () => {
 			expect(registry.getError()).toBeUndefined();
 			expect(openrouter.find((m) => m.id === "custom/cached-model")?.promptCache).toEqual({ short: 120 });
 			expect(openrouter.find((m) => m.id === "anthropic/claude-sonnet-4")?.promptCache).toEqual({ short: 300 });
-			expect(openrouter.find((m) => m.id === "anthropic/claude-opus-4")?.promptCache).toBeUndefined();
+			expect(openrouter.find((m) => m.id === "anthropic/claude-opus-4.1")?.promptCache).toBeUndefined();
 			// Overrides merge per tier with the built-in catalog.
 			expect(registry.find("anthropic", "claude-sonnet-4-6")?.promptCache).toEqual({ short: 300, long: 1800 });
 		});
@@ -898,7 +898,7 @@ describe("ModelRegistry", () => {
 			const registry = await createModelRegistry(authStorage, modelsJsonPath);
 			const models = getModelsForProvider(registry, "openrouter");
 			const sonnet = models.find((model) => model.id === "anthropic/claude-sonnet-4");
-			const opus = models.find((model) => model.id === "anthropic/claude-opus-4");
+			const opus = models.find((model) => model.id === "anthropic/claude-opus-4.1");
 
 			expect((sonnet?.compat as OpenAICompletionsCompat | undefined)?.supportsFinishReason).toBe(false);
 			expect((opus?.compat as OpenAICompletionsCompat | undefined)?.supportsFinishReason).toBe(true);
@@ -933,7 +933,7 @@ describe("ModelRegistry", () => {
 						"anthropic/claude-sonnet-4": {
 							compat: { openRouterRouting: { only: ["amazon-bedrock"] } },
 						},
-						"anthropic/claude-opus-4": {
+						"anthropic/claude-opus-4.1": {
 							compat: { openRouterRouting: { only: ["anthropic"] } },
 						},
 					},
@@ -944,7 +944,7 @@ describe("ModelRegistry", () => {
 			const models = getModelsForProvider(registry, "openrouter");
 
 			const sonnet = models.find((m) => m.id === "anthropic/claude-sonnet-4");
-			const opus = models.find((m) => m.id === "anthropic/claude-opus-4");
+			const opus = models.find((m) => m.id === "anthropic/claude-opus-4.1");
 
 			const sonnetCompat = sonnet?.compat as OpenAICompletionsCompat | undefined;
 			const opusCompat = opus?.compat as OpenAICompletionsCompat | undefined;
@@ -973,7 +973,7 @@ describe("ModelRegistry", () => {
 			expect(sonnet?.name).toBe("Proxied Sonnet");
 
 			// Other models should have the baseUrl but not the name override
-			const opus = models.find((m) => m.id === "anthropic/claude-opus-4");
+			const opus = models.find((m) => m.id === "anthropic/claude-opus-4.1");
 			expect(opus?.baseUrl).toBe("https://my-proxy.example.com/v1");
 			expect(opus?.name).not.toBe("Proxied Sonnet");
 		});
diff --git a/packages/coding-agent/test/model-resolver.test.ts b/packages/coding-agent/test/model-resolver.test.ts
index 8f37b7054..ebed94c33 100644
--- a/packages/coding-agent/test/model-resolver.test.ts
+++ b/packages/coding-agent/test/model-resolver.test.ts
@@ -735,7 +735,7 @@ describe("default model selection", () => {
 	});
 
 	test("xai default tracks current model", () => {
-		expect(defaultModelPerProvider.xai).toBe("grok-4.6");
+		expect(defaultModelPerProvider.xai).toBe("grok-4.7");
 	});
 
 	test("qwen token plan individual default tracks current model", () => {
diff --git a/packages/coding-agent/test/suite/regressions/9789-context-handler-system-messages.test.ts b/packages/coding-agent/test/suite/regressions/9789-context-handler-system-messages.test.ts
new file mode 100644
index 000000000..aa3816dcb
--- /dev/null
+++ b/packages/coding-agent/test/suite/regressions/9789-context-handler-system-messages.test.ts
@@ -0,0 +1,226 @@
+import type { AgentMessage } from "@earendil-works/pi-agent-core";
+import {
+	fauxAssistantMessage,
+	getCurrentSystemPrompt,
+	getCurrentTools,
+	type TranscriptContext,
+} from "@earendil-works/pi-ai";
+import { afterEach, describe, expect, it } from "vitest";
+import type { ExtensionFactory } from "../../../src/index.ts";
+import { createHarness, type Harness } from "../harness.ts";
+
+/** Compaction supplied by an extension hook, as in the reported sessions. */
+const compactViaHook: ExtensionFactory = (pi) => {
+	pi.on("session_before_compact", async (event) => ({
+		compaction: {
+			summary: "extension summary",
+			firstKeptEntryId: event.preparation.firstKeptEntryId,
+			tokensBefore: event.preparation.tokensBefore,
+			details: { source: "test" },
+		},
+	}));
+};
+
+function captureRequest(harness: Harness, text: string): () => TranscriptContext {
+	let request: TranscriptContext | undefined;
+	harness.setResponses([
+		(context) => {
+			request = context;
+			return fauxAssistantMessage(text);
+		},
+	]);
+	return () => {
+		if (!request) throw new Error("expected a provider request");
+		return request;
+	};
+}
+
+function toolNames(context: TranscriptContext): string[] {
+	return getCurrentTools(context.messages).map((tool) => tool.name);
+}
+
+async function compactSession(harness: Harness): Promise<void> {
+	harness.settingsManager.applyOverrides({ compaction: { keepRecentTokens: 1 } });
+	harness.setResponses([fauxAssistantMessage("one"), fauxAssistantMessage("two")]);
+	await harness.session.prompt("first");
+	await harness.session.prompt("second");
+	await harness.session.compact();
+	expect(harness.session.messages.map((message) => message.role).slice(0, 2)).toEqual(["system", "compactionSummary"]);
+}
+
+describe("context handlers and system messages", () => {
+	const harnesses: Harness[] = [];
+
+	afterEach(() => {
+		while (harnesses.length > 0) harnesses.pop()?.cleanup();
+	});
+
+	// Regression #9789, #9822: pruning from the compaction summary dropped the prompt and tool checkpoint.
+	it("keeps the prompt and tools when a handler slices from the compaction summary", async () => {
+		const seen: AgentMessage[][] = [];
+		const harness = await createHarness({
+			extensionFactories: [
+				compactViaHook,
+				(pi) => {
+					pi.on("context", async (event) => {
+						seen.push(event.messages);
+						const summary = event.messages.findIndex((message) => message.role === "compactionSummary");
+						return { messages: event.messages.slice(summary) };
+					});
+				},
+			],
+		});
+		harnesses.push(harness);
+		await compactSession(harness);
+		const getRequest = captureRequest(harness, "after compaction");
+
+		await harness.session.prompt("third");
+
+		const request = getRequest();
+		expect(seen.at(-1)?.some((message) => message.role === "system")).toBe(false);
+		expect(request.messages[0]?.role).toBe("system");
+		expect(toolNames(request)).toEqual(harness.session.getActiveToolNames());
+		expect(getCurrentSystemPrompt(request.messages)).toBe(harness.session.systemPrompt);
+		expect(request.messages.filter((message) => message.role === "system")).toHaveLength(1);
+	});
+
+	it("keeps mid-conversation system messages in place when a handler leaves the conversation unchanged", async () => {
+		let turn = 0;
+		const harness = await createHarness({
+			extensionFactories: [
+				(pi) => {
+					pi.on("before_agent_start", (event) => {
+						if (++turn === 2) event.systemPromptOptions.sections.plan_mode = "Plan only.";
+					});
+					pi.on("context", async (event) => ({ messages: event.messages }));
+				},
+			],
+		});
+		harnesses.push(harness);
+		harness.setResponses([fauxAssistantMessage("one")]);
+		await harness.session.prompt("first");
+		const getRequest = captureRequest(harness, "two");
+
+		await harness.session.prompt("second");
+
+		const systemMessages = getRequest().messages.filter((message) => message.role === "system");
+		expect(systemMessages).toHaveLength(2);
+		expect(systemMessages[1]?.sections).toEqual({ plan_mode: "<plan_mode>\nPlan only.\n</plan_mode>" });
+	});
+
+	it("applies in-place edits to event.messages without a return value", async () => {
+		const harness = await createHarness({
+			extensionFactories: [
+				(pi) => {
+					pi.on("context", async (event) => {
+						event.messages.splice(0, 0, {
+							role: "user",
+							content: [{ type: "text", text: "injected" }],
+							timestamp: 0,
+						});
+					});
+				},
+			],
+		});
+		harnesses.push(harness);
+		const getRequest = captureRequest(harness, "done");
+
+		await harness.session.prompt("hello");
+
+		const request = getRequest();
+		expect(request.messages.map((message) => message.role)).toEqual(["system", "user", "user"]);
+		expect(toolNames(request)).toEqual(harness.session.getActiveToolNames());
+	});
+
+	it("keeps system messages a handler adds after the replayed head", async () => {
+		const harness = await createHarness({
+			extensionFactories: [
+				(pi) => {
+					pi.on("context", async (event) => ({
+						messages: [{ role: "system", content: "ephemeral reminder", timestamp: 0 }, ...event.messages],
+					}));
+				},
+			],
+		});
+		harnesses.push(harness);
+		const getRequest = captureRequest(harness, "done");
+
+		await harness.session.prompt("hello");
+
+		const request = getRequest();
+		expect(request.messages.map((message) => message.role)).toEqual(["system", "system", "user"]);
+		expect(toolNames(request)).toEqual(harness.session.getActiveToolNames());
+		expect(getCurrentSystemPrompt(request.messages)).toContain(harness.session.systemPrompt);
+		expect(getCurrentSystemPrompt(request.messages)).toContain("ephemeral reminder");
+	});
+});
+
+describe("context_with_system handlers", () => {
+	const harnesses: Harness[] = [];
+
+	afterEach(() => {
+		while (harnesses.length > 0) harnesses.pop()?.cleanup();
+	});
+
+	it("runs after context handlers on the restored transcript and sends its output verbatim", async () => {
+		const seen: AgentMessage[][] = [];
+		const harness = await createHarness({
+			extensionFactories: [
+				compactViaHook,
+				(pi) => {
+					pi.on("context_with_system", async (event) => {
+						seen.push(event.messages);
+						return {
+							messages: event.messages.map((message) =>
+								message.role === "system" && message.toolsAdded
+									? { ...message, toolsAdded: message.toolsAdded.filter((tool) => tool.name !== "bash") }
+									: message,
+							),
+						};
+					});
+					// Registered after, but runs first: context handlers precede context_with_system.
+					pi.on("context", async (event) => {
+						const summary = event.messages.findIndex((message) => message.role === "compactionSummary");
+						return { messages: event.messages.slice(summary) };
+					});
+				},
+			],
+		});
+		harnesses.push(harness);
+		await compactSession(harness);
+		const getRequest = captureRequest(harness, "after compaction");
+
+		await harness.session.prompt("third");
+
+		const input = seen.at(-1);
+		expect(input?.[0]?.role).toBe("system");
+		expect(input?.[1]?.role).toBe("compactionSummary");
+		expect(harness.session.getActiveToolNames()).toContain("bash");
+		expect(toolNames(getRequest())).toEqual(harness.session.getActiveToolNames().filter((name) => name !== "bash"));
+	});
+
+	it("reports a handler that drops the leading system message but honors its output", async () => {
+		const harness = await createHarness({
+			extensionFactories: [
+				(pi) => {
+					pi.on("context_with_system", async (event) => ({
+						messages: event.messages.filter((message) => message.role !== "system"),
+					}));
+				},
+			],
+		});
+		harnesses.push(harness);
+		const errors: string[] = [];
+		harness.session.extensionRunner.onError((error) => {
+			errors.push(`${error.event}: ${error.error}`);
+		});
+		const getRequest = captureRequest(harness, "done");
+
+		await harness.session.prompt("hello");
+
+		expect(getRequest().messages.map((message) => message.role)).toEqual(["user"]);
+		expect(errors).toEqual([
+			expect.stringMatching(/^context_with_system: Handler removed the leading system message/),
+		]);
+	});
+});
diff --git a/packages/durable/CHANGELOG.md b/packages/durable/CHANGELOG.md
index 39d2de378..8717705e3 100644
--- a/packages/durable/CHANGELOG.md
+++ b/packages/durable/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ## [Unreleased]
 
+## [0.87.0] - 2026-09-21
+
 ## [0.86.1] - 2026-09-20
 
 ## [0.86.0] - 2026-09-19
diff --git a/packages/durable/package.json b/packages/durable/package.json
index e85d868cd..c060d2608 100644
--- a/packages/durable/package.json
+++ b/packages/durable/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "@earendil-works/pi-durable",
-	"version": "0.86.1",
+	"version": "0.87.0",
 	"description": "Durable conversation, task, and document runtime for Pi",
 	"type": "module",
 	"main": "./dist/index.js",
@@ -42,8 +42,8 @@
 		"node": ">=22.19.0"
 	},
 	"dependencies": {
-		"@earendil-works/chord": "^0.86.1",
-		"@earendil-works/pi-ai": "^0.86.1"
+		"@earendil-works/chord": "^0.87.0",
+		"@earendil-works/pi-ai": "^0.87.0"
 	},
 	"devDependencies": {
 		"shx": "0.4.0",
diff --git a/packages/evals/package.json b/packages/evals/package.json
index b89d946d1..20183dc83 100644
--- a/packages/evals/package.json
+++ b/packages/evals/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "@earendil-works/pi-evals",
-	"version": "0.86.1",
+	"version": "0.87.0",
 	"private": true,
 	"type": "module",
 	"scripts": {
@@ -12,8 +12,8 @@
 	},
 	"devDependencies": {
 		"autoevals": "0.3.0",
-		"@earendil-works/pi-ai": "^0.86.1",
-		"@earendil-works/pi-coding-agent": "^0.86.1",
+		"@earendil-works/pi-ai": "^0.87.0",
+		"@earendil-works/pi-coding-agent": "^0.87.0",
 		"@types/node": "22.19.19",
 		"@vitest-evals/core": "0.15.0",
 		"shx": "0.4.0",
diff --git a/packages/protocol/CHANGELOG.md b/packages/protocol/CHANGELOG.md
index 6147cd8f5..fe62bde3d 100644
--- a/packages/protocol/CHANGELOG.md
+++ b/packages/protocol/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ## [Unreleased]
 
+## [0.87.0] - 2026-09-21
+
 ## [0.86.1] - 2026-09-20
 
 ## [0.86.0] - 2026-09-19
diff --git a/packages/protocol/package.json b/packages/protocol/package.json
index 602af9be5..883a0a1d2 100644
--- a/packages/protocol/package.json
+++ b/packages/protocol/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "@earendil-works/pi-protocol",
-	"version": "0.86.1",
+	"version": "0.87.0",
 	"description": "Transport-neutral CBOR protocol for remote pi sessions",
 	"type": "module",
 	"main": "./dist/index.js",
@@ -39,7 +39,7 @@
 		"node": ">=22.19.0"
 	},
 	"dependencies": {
-		"@earendil-works/chord": "^0.86.1",
+		"@earendil-works/chord": "^0.87.0",
 		"typebox": "1.3.27"
 	},
 	"devDependencies": {
diff --git a/packages/server/CHANGELOG.md b/packages/server/CHANGELOG.md
index 38e73caf1..bda8d300f 100644
--- a/packages/server/CHANGELOG.md
+++ b/packages/server/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ## [Unreleased]
 
+## [0.87.0] - 2026-09-21
+
 ## [0.86.1] - 2026-09-20
 
 ## [0.86.0] - 2026-09-19
diff --git a/packages/server/package.json b/packages/server/package.json
index 30a2f9a8d..3829f33ad 100644
--- a/packages/server/package.json
+++ b/packages/server/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "@earendil-works/pi-server",
-	"version": "0.86.1",
+	"version": "0.87.0",
 	"description": "experimental server package for pi",
 	"type": "module",
 	"main": "./dist/index.js",
@@ -47,9 +47,9 @@
 		"node": ">=22.19.0"
 	},
 	"dependencies": {
-		"@earendil-works/chord": "^0.86.1",
-		"@earendil-works/pi-agent-core": "^0.86.1",
-		"@earendil-works/pi-protocol": "^0.86.1"
+		"@earendil-works/chord": "^0.87.0",
+		"@earendil-works/pi-agent-core": "^0.87.0",
+		"@earendil-works/pi-protocol": "^0.87.0"
 	},
 	"devDependencies": {
 		"shx": "0.4.0",
diff --git a/packages/session-backends/sqlite-node/CHANGELOG.md b/packages/session-backends/sqlite-node/CHANGELOG.md
index d915d6703..5ab3077bf 100644
--- a/packages/session-backends/sqlite-node/CHANGELOG.md
+++ b/packages/session-backends/sqlite-node/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ## [Unreleased]
 
+## [0.87.0] - 2026-09-21
+
 ## [0.86.1] - 2026-09-20
 
 ## [0.86.0] - 2026-09-19
diff --git a/packages/session-backends/sqlite-node/package.json b/packages/session-backends/sqlite-node/package.json
index e080c830b..f825a38eb 100644
--- a/packages/session-backends/sqlite-node/package.json
+++ b/packages/session-backends/sqlite-node/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "@earendil-works/pi-session-backend-sqlite-node",
-	"version": "0.86.1",
+	"version": "0.87.0",
 	"description": "Node sqlite session backend for @earendil-works/pi-agent-core sessions",
 	"type": "module",
 	"main": "./dist/index.js",
@@ -35,8 +35,8 @@
 		"node": ">=22.19.0"
 	},
 	"dependencies": {
-		"@earendil-works/pi-ai": "^0.86.1",
-		"@earendil-works/pi-agent-core": "^0.86.1"
+		"@earendil-works/pi-ai": "^0.87.0",
+		"@earendil-works/pi-agent-core": "^0.87.0"
 	},
 	"devDependencies": {
 		"@vitest/coverage-v8": "4.1.9",
diff --git a/packages/telemetry/CHANGELOG.md b/packages/telemetry/CHANGELOG.md
index 11c036040..b1af6f4b2 100644
--- a/packages/telemetry/CHANGELOG.md
+++ b/packages/telemetry/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ## [Unreleased]
 
+## [0.87.0] - 2026-09-21
+
 ## [0.86.1] - 2026-09-20
 
 ## [0.86.0] - 2026-09-19
diff --git a/packages/telemetry/package.json b/packages/telemetry/package.json
index de9ea1aa2..99aba7649 100644
--- a/packages/telemetry/package.json
+++ b/packages/telemetry/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "@earendil-works/pi-telemetry",
-	"version": "0.86.1",
+	"version": "0.87.0",
 	"description": "Vendor-neutral telemetry contracts and typed schema utilities for pi",
 	"type": "module",
 	"main": "./dist/index.js",
diff --git a/packages/tui/CHANGELOG.md b/packages/tui/CHANGELOG.md
index 26e29a42e..9da53a3a1 100644
--- a/packages/tui/CHANGELOG.md
+++ b/packages/tui/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ## [Unreleased]
 
+## [0.87.0] - 2026-09-21
+
 ## [0.86.1] - 2026-09-20
 
 ## [0.86.0] - 2026-09-19
diff --git a/packages/tui/package.json b/packages/tui/package.json
index 35d12c859..3b476a509 100644
--- a/packages/tui/package.json
+++ b/packages/tui/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "@earendil-works/pi-tui",
-	"version": "0.86.1",
+	"version": "0.87.0",
 	"description": "Terminal User Interface library with differential rendering for efficient text-based applications",
 	"type": "module",
 	"main": "dist/index.js",
diff --git a/packages/tui/src/tui-alt-screen.ts b/packages/tui/src/tui-alt-screen.ts
index 1b3d2614d..cc9a04f43 100644
--- a/packages/tui/src/tui-alt-screen.ts
+++ b/packages/tui/src/tui-alt-screen.ts
@@ -1630,11 +1630,14 @@ export class TuiAltScreen extends TuiBase implements ViewportTUI {
 		const row = clip.y + clip.height - 1;
 		if (row >= screen.length || isImageLine(screen[row] ?? "")) return screen;
 		const scrollbarColumn = box ? getScrollbarGeometry(box)?.column : undefined;
-		const availableWidth = Math.max(0, (scrollbarColumn ?? clip.x + clip.width) - clip.x);
-		const text = truncateToWidth(this.scrollToEndIndicator(), availableWidth, "");
+		const label = truncateToWidth(this.scrollToEndIndicator(), clip.width, "");
+		const labelWidth = visibleWidth(label);
+		const column = clip.x + Math.floor((clip.width - labelWidth) / 2);
+		const rightEdge = scrollbarColumn ?? clip.x + clip.width;
+		const availableWidth = Math.max(0, rightEdge - column);
+		const text = truncateToWidth(label, availableWidth, "");
 		const textWidth = visibleWidth(text);
 		if (textWidth === 0) return screen;
-		const column = clip.x + Math.floor((availableWidth - textWidth) / 2);
 		const result = [...screen];
 		result[row] = compositeTuiLine(result[row] ?? "", text, column, textWidth, width);
 		this.scrollToEndIndicatorRect = { row, column, width: textWidth };
diff --git a/packages/tui/test/tui-alt-screen.test.ts b/packages/tui/test/tui-alt-screen.test.ts
index fa007d2ad..e79169127 100644
--- a/packages/tui/test/tui-alt-screen.test.ts
+++ b/packages/tui/test/tui-alt-screen.test.ts
@@ -138,7 +138,51 @@ describe("TuiAltScreen", () => {
 		tui.stop();
 	});
 
-	it("leaves the scrollbar clickable when the jump-to-end indicator spans the transcript", async () => {
+	it("keeps the jump-to-end indicator centered as the auto scrollbar hides and reappears", async () => {
+		// Regression test for #9136: auto scrollbar visibility must not move the indicator.
+		const terminal = new VirtualTerminal(80, 6);
+		const label = " ↓ Jump to latest message · End ";
+		const tui = new TuiAltScreen(terminal, undefined, undefined, {
+			scrollToEndIndicator: () => label,
+		});
+		const transcript = new ScrollView(
+			new Text(Array.from({ length: 20 }, (_, index) => `line ${index + 1}`).join("\n"), 0, 0),
+			{ follow: "end", primary: true, scrollbar: "auto", scrollbarHideDelayMs: 0 },
+		);
+		tui.setLayoutRoot(transcript);
+		tui.start();
+		try {
+			await terminal.waitForRender();
+
+			// Scrolling over the track keeps the scrollbar visible until the pointer leaves.
+			terminal.sendInput("\x1b[<64;80;1M");
+			await terminal.waitForRender();
+			assert.strictEqual(transcript.isScrollbarVisible, true);
+			assert.strictEqual(transcript.isFollowingEnd, false);
+			const scrollTop = transcript.scrollTop;
+			const visibleColumn = terminal.getViewport()[5].indexOf(label);
+
+			// Leaving the track lets the auto-hide timer expire without changing the content.
+			terminal.sendInput("\x1b[<35;79;1M");
+			await terminal.waitForRender();
+			assert.strictEqual(transcript.isScrollbarVisible, false);
+			assert.strictEqual(transcript.scrollTop, scrollTop);
+			const hiddenColumn = terminal.getViewport()[5].indexOf(label);
+
+			terminal.sendInput("\x1b[<35;80;1M");
+			await terminal.waitForRender();
+			assert.strictEqual(transcript.isScrollbarVisible, true);
+			assert.strictEqual(transcript.scrollTop, scrollTop);
+			const revealedColumn = terminal.getViewport()[5].indexOf(label);
+
+			assert.deepStrictEqual([visibleColumn, hiddenColumn, revealedColumn], [24, 24, 24]);
+		} finally {
+			tui.stop();
+		}
+	});
+
+	it("leaves the scrollbar visible and clickable when the jump-to-end indicator spans the transcript", async () => {
+		// Regression coverage for #9136: centering must not paint or capture clicks over the scrollbar.
 		const terminal = new VirtualTerminal(30, 6);
 		const tui = new TuiAltScreen(terminal, undefined, undefined, {
 			scrollToEndIndicator: () => "↓".repeat(30),
@@ -161,6 +205,7 @@ describe("TuiAltScreen", () => {
 		assert.strictEqual(transcript.isFollowingEnd, false);
 
 		// The indicator must not intercept a press on the scrollbar's last column.
+		assert.strictEqual(terminal.getViewport()[3], `${"↓".repeat(29)}┃`);
 		terminal.sendInput("\x1b[<0;30;4M");
 		terminal.sendInput("\x1b[<0;30;4m");
 		await terminal.waitForRender();