test(context-injector): update tests for synthetic part injection

- Remove injectPendingContext test block (~118 lines)
- Remove createContextInjectorHook test block (~50 lines)
- Remove imports of removed functions
- Remove exports of removed functions from index.ts
- Keep createContextInjectorMessagesTransformHook tests (updated in Task 2)

src/features/context-injector/index.ts

@@ -1,7 +1,5 @@
 export { ContextCollector, contextCollector } from "./collector"
 export {
-  injectPendingContext,
-  createContextInjectorHook,
   createContextInjectorMessagesTransformHook,
 } from "./injector"
 export type {

src/features/context-injector/injector.test.ts

@@ -1,181 +1,9 @@
 import { describe, it, expect, beforeEach } from "bun:test"
 import { ContextCollector } from "./collector"
 import {
-  injectPendingContext,
-  createContextInjectorHook,
   createContextInjectorMessagesTransformHook,
 } from "./injector"
 
-describe("injectPendingContext", () => {
-  let collector: ContextCollector
-
-  beforeEach(() => {
-    collector = new ContextCollector()
-  })
-
-  describe("when parts have text content", () => {
-    it("prepends context to first text part", () => {
-      // #given
-      const sessionID = "ses_inject1"
-      collector.register(sessionID, {
-        id: "ulw",
-        source: "keyword-detector",
-        content: "Ultrawork mode activated",
-      })
-      const parts = [{ type: "text", text: "User message" }]
-
-      // #when
-      const result = injectPendingContext(collector, sessionID, parts)
-
-      // #then
-      expect(result.injected).toBe(true)
-      expect(parts[0].text).toContain("Ultrawork mode activated")
-      expect(parts[0].text).toContain("User message")
-    })
-
-    it("uses separator between context and original message", () => {
-      // #given
-      const sessionID = "ses_inject2"
-      collector.register(sessionID, {
-        id: "ctx",
-        source: "keyword-detector",
-        content: "Context content",
-      })
-      const parts = [{ type: "text", text: "Original message" }]
-
-      // #when
-      injectPendingContext(collector, sessionID, parts)
-
-      // #then
-      expect(parts[0].text).toBe("Context content\n\n---\n\nOriginal message")
-    })
-
-    it("consumes context after injection", () => {
-      // #given
-      const sessionID = "ses_inject3"
-      collector.register(sessionID, {
-        id: "ctx",
-        source: "keyword-detector",
-        content: "Context",
-      })
-      const parts = [{ type: "text", text: "Message" }]
-
-      // #when
-      injectPendingContext(collector, sessionID, parts)
-
-      // #then
-      expect(collector.hasPending(sessionID)).toBe(false)
-    })
-
-    it("returns injected=false when no pending context", () => {
-      // #given
-      const sessionID = "ses_empty"
-      const parts = [{ type: "text", text: "Message" }]
-
-      // #when
-      const result = injectPendingContext(collector, sessionID, parts)
-
-      // #then
-      expect(result.injected).toBe(false)
-      expect(parts[0].text).toBe("Message")
-    })
-  })
-
-  describe("when parts have no text content", () => {
-    it("does not inject and preserves context", () => {
-      // #given
-      const sessionID = "ses_notext"
-      collector.register(sessionID, {
-        id: "ctx",
-        source: "keyword-detector",
-        content: "Context",
-      })
-      const parts = [{ type: "image", url: "https://example.com/img.png" }]
-
-      // #when
-      const result = injectPendingContext(collector, sessionID, parts)
-
-      // #then
-      expect(result.injected).toBe(false)
-      expect(collector.hasPending(sessionID)).toBe(true)
-    })
-  })
-
-  describe("with multiple text parts", () => {
-    it("injects into first text part only", () => {
-      // #given
-      const sessionID = "ses_multi"
-      collector.register(sessionID, {
-        id: "ctx",
-        source: "keyword-detector",
-        content: "Context",
-      })
-      const parts = [
-        { type: "text", text: "First" },
-        { type: "text", text: "Second" },
-      ]
-
-      // #when
-      injectPendingContext(collector, sessionID, parts)
-
-      // #then
-      expect(parts[0].text).toContain("Context")
-      expect(parts[1].text).toBe("Second")
-    })
-  })
-})
-
-describe("createContextInjectorHook", () => {
-  let collector: ContextCollector
-
-  beforeEach(() => {
-    collector = new ContextCollector()
-  })
-
-  describe("chat.message handler", () => {
-    it("injects pending context into output parts", async () => {
-      // #given
-      const hook = createContextInjectorHook(collector)
-      const sessionID = "ses_hook1"
-      collector.register(sessionID, {
-        id: "ctx",
-        source: "keyword-detector",
-        content: "Hook context",
-      })
-      const input = { sessionID }
-      const output = {
-        message: {},
-        parts: [{ type: "text", text: "User message" }],
-      }
-
-      // #when
-      await hook["chat.message"](input, output)
-
-      // #then
-      expect(output.parts[0].text).toContain("Hook context")
-      expect(output.parts[0].text).toContain("User message")
-      expect(collector.hasPending(sessionID)).toBe(false)
-    })
-
-    it("does nothing when no pending context", async () => {
-      // #given
-      const hook = createContextInjectorHook(collector)
-      const sessionID = "ses_hook2"
-      const input = { sessionID }
-      const output = {
-        message: {},
-        parts: [{ type: "text", text: "User message" }],
-      }
-
-      // #when
-      await hook["chat.message"](input, output)
-
-      // #then
-      expect(output.parts[0].text).toBe("User message")
-    })
-  })
-})
-
 describe("createContextInjectorMessagesTransformHook", () => {
   let collector: ContextCollector