test: add shared chat helper coverage

src/shared/chat-envelope.test.ts

@@ -0,0 +1,23 @@
+import { describe, expect, it } from "vitest";
+import { stripEnvelope, stripMessageIdHints } from "./chat-envelope.js";
+
+describe("shared/chat-envelope", () => {
+  it("strips recognized channel and timestamp envelope prefixes only", () => {
+    expect(stripEnvelope("[WhatsApp 2026-01-24 13:36] hello")).toBe("hello");
+    expect(stripEnvelope("[2026-01-24T13:36Z] hello")).toBe("hello");
+    expect(stripEnvelope("[Custom Sender] hello")).toBe("[Custom Sender] hello");
+  });
+
+  it("keeps non-envelope headers and preserves unmatched text", () => {
+    expect(stripEnvelope("hello")).toBe("hello");
+    expect(stripEnvelope("[note] hello")).toBe("[note] hello");
+  });
+
+  it("removes standalone message id hint lines but keeps inline mentions", () => {
+    expect(stripMessageIdHints("hello\n[message_id: abc123]")).toBe("hello");
+    expect(stripMessageIdHints("hello\n [message_id: abc123] \nworld")).toBe("hello\nworld");
+    expect(stripMessageIdHints("I typed [message_id: abc123] inline")).toBe(
+      "I typed [message_id: abc123] inline",
+    );
+  });
+});

src/shared/chat-message-content.test.ts

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+import { describe, expect, it } from "vitest";
+import { extractFirstTextBlock } from "./chat-message-content.js";
+
+describe("shared/chat-message-content", () => {
+  it("extracts the first text block from array content", () => {
+    expect(
+      extractFirstTextBlock({
+        content: [{ text: "hello" }, { text: "world" }],
+      }),
+    ).toBe("hello");
+  });
+
+  it("returns undefined for missing, empty, or non-text content", () => {
+    expect(extractFirstTextBlock(null)).toBeUndefined();
+    expect(extractFirstTextBlock({ content: [] })).toBeUndefined();
+    expect(extractFirstTextBlock({ content: [{ type: "image" }] })).toBeUndefined();
+    expect(extractFirstTextBlock({ content: ["hello"] })).toBeUndefined();
+  });
+});

src/shared/text-chunking.test.ts

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+import { describe, expect, it } from "vitest";
+import { chunkTextByBreakResolver } from "./text-chunking.js";
+
+describe("shared/text-chunking", () => {
+  it("returns empty for blank input and the full text when under limit", () => {
+    expect(chunkTextByBreakResolver("", 10, () => 5)).toEqual([]);
+    expect(chunkTextByBreakResolver("hello", 10, () => 2)).toEqual(["hello"]);
+  });
+
+  it("splits at resolver-provided breakpoints and trims separator boundaries", () => {
+    expect(
+      chunkTextByBreakResolver("alpha beta gamma", 10, (window) => window.lastIndexOf(" ")),
+    ).toEqual(["alpha", "beta gamma"]);
+  });
+
+  it("falls back to hard limits for invalid break indexes", () => {
+    expect(chunkTextByBreakResolver("abcdefghij", 4, () => Number.NaN)).toEqual([
+      "abcd",
+      "efgh",
+      "ij",
+    ]);
+    expect(chunkTextByBreakResolver("abcdefghij", 4, () => 99)).toEqual(["abcd", "efgh", "ij"]);
+    expect(chunkTextByBreakResolver("abcdefghij", 4, () => 0)).toEqual(["abcd", "efgh", "ij"]);
+  });
+
+  it("skips empty chunks created by whitespace-only segments", () => {
+    expect(
+      chunkTextByBreakResolver("word     next", 5, (window) => window.lastIndexOf(" ")),
+    ).toEqual(["word", "next"]);
+  });
+});