diff --git a/packages/opencode/test/session/instruction.test.ts b/packages/opencode/test/session/instruction.test.ts
index e0bf94a950..2d12563c6a 100644
--- a/packages/opencode/test/session/instruction.test.ts
+++ b/packages/opencode/test/session/instruction.test.ts
@@ -4,6 +4,201 @@ import { InstructionPrompt } from "../../src/session/instruction"
 import { Instance } from "../../src/project/instance"
 import { Global } from "../../src/global"
 import { tmpdir } from "../fixture/fixture"
+import type { MessageV2 } from "../../src/session/message-v2"
+import { SessionID, MessageID, PartID } from "../../src/session/schema"
+
+// ─── Helpers for InstructionPrompt.loaded() ─────────────────────────────────
+
+const sid = SessionID.make("test-session")
+
+function makeUserMsg(id: string, parts: MessageV2.Part[]): MessageV2.WithParts {
+  return {
+    info: {
+      id: MessageID.make(id),
+      sessionID: sid,
+      role: "user" as const,
+      time: { created: 0 },
+      agent: "user",
+      model: { providerID: "test" as any, modelID: "test" as any },
+      tools: {},
+      mode: "",
+    } as MessageV2.User,
+    parts,
+  }
+}
+
+function readToolPart(opts: {
+  id: string
+  messageID: string
+  status: "completed" | "running" | "error"
+  loaded?: unknown[]
+  compacted?: number
+}): MessageV2.ToolPart {
+  if (opts.status === "completed") {
+    return {
+      id: PartID.make(opts.id),
+      sessionID: sid,
+      messageID: MessageID.make(opts.messageID),
+      type: "tool",
+      callID: opts.id,
+      tool: "read",
+      state: {
+        status: "completed",
+        input: {},
+        output: "file content",
+        title: "Read file",
+        metadata: opts.loaded !== undefined ? { loaded: opts.loaded } : {},
+        time: { start: 0, end: 1, ...(opts.compacted !== undefined ? { compacted: opts.compacted } : {}) },
+      },
+    } as MessageV2.ToolPart
+  }
+  if (opts.status === "running") {
+    return {
+      id: PartID.make(opts.id),
+      sessionID: sid,
+      messageID: MessageID.make(opts.messageID),
+      type: "tool",
+      callID: opts.id,
+      tool: "read",
+      state: {
+        status: "running",
+        input: {},
+        time: { start: 0 },
+      },
+    } as MessageV2.ToolPart
+  }
+  return {
+    id: PartID.make(opts.id),
+    sessionID: sid,
+    messageID: MessageID.make(opts.messageID),
+    type: "tool",
+    callID: opts.id,
+    tool: "read",
+    state: {
+      status: "error",
+      input: {},
+      error: "read failed",
+      time: { start: 0, end: 1 },
+    },
+  } as MessageV2.ToolPart
+}
+
+function nonReadToolPart(opts: {
+  id: string
+  messageID: string
+  tool: string
+  loaded?: unknown[]
+}): MessageV2.ToolPart {
+  return {
+    id: PartID.make(opts.id),
+    sessionID: sid,
+    messageID: MessageID.make(opts.messageID),
+    type: "tool",
+    callID: opts.id,
+    tool: opts.tool,
+    state: {
+      status: "completed",
+      input: {},
+      output: "done",
+      title: "Tool done",
+      metadata: opts.loaded !== undefined ? { loaded: opts.loaded } : {},
+      time: { start: 0, end: 1 },
+    },
+  } as MessageV2.ToolPart
+}
+
+// ─── InstructionPrompt.loaded() ─────────────────────────────────────────────
+
+describe("InstructionPrompt.loaded", () => {
+  test("returns empty set for messages with no tool parts", () => {
+    const textPart: MessageV2.Part = {
+      id: PartID.make("p1"),
+      sessionID: sid,
+      messageID: MessageID.make("m1"),
+      type: "text",
+      content: "hello",
+    } as MessageV2.Part
+    const result = InstructionPrompt.loaded([makeUserMsg("m1", [textPart])])
+    expect(result.size).toBe(0)
+  })
+
+  test("extracts paths from completed read tool parts with loaded metadata", () => {
+    const part = readToolPart({
+      id: "p1",
+      messageID: "m1",
+      status: "completed",
+      loaded: ["/project/subdir/AGENTS.md", "/project/lib/AGENTS.md"],
+    })
+    const result = InstructionPrompt.loaded([makeUserMsg("m1", [part])])
+    expect(result.size).toBe(2)
+    expect(result.has("/project/subdir/AGENTS.md")).toBe(true)
+    expect(result.has("/project/lib/AGENTS.md")).toBe(true)
+  })
+
+  test("skips compacted tool parts", () => {
+    const part = readToolPart({
+      id: "p1",
+      messageID: "m1",
+      status: "completed",
+      loaded: ["/project/AGENTS.md"],
+      compacted: 12345,
+    })
+    const result = InstructionPrompt.loaded([makeUserMsg("m1", [part])])
+    expect(result.size).toBe(0)
+  })
+
+  test("skips non-read tool parts even with loaded metadata", () => {
+    const part = nonReadToolPart({
+      id: "p1",
+      messageID: "m1",
+      tool: "bash",
+      loaded: ["/project/AGENTS.md"],
+    })
+    const result = InstructionPrompt.loaded([makeUserMsg("m1", [part])])
+    expect(result.size).toBe(0)
+  })
+
+  test("skips non-completed read tool parts", () => {
+    const runningPart = readToolPart({ id: "p1", messageID: "m1", status: "running" })
+    const errorPart = readToolPart({ id: "p2", messageID: "m1", status: "error" })
+    const result = InstructionPrompt.loaded([makeUserMsg("m1", [runningPart, errorPart])])
+    expect(result.size).toBe(0)
+  })
+
+  test("filters out non-string entries in the loaded array", () => {
+    const part = readToolPart({
+      id: "p1",
+      messageID: "m1",
+      status: "completed",
+      loaded: ["/valid/path", 42, null, { nested: true }, "/another/path", undefined],
+    })
+    const result = InstructionPrompt.loaded([makeUserMsg("m1", [part])])
+    expect(result.size).toBe(2)
+    expect(result.has("/valid/path")).toBe(true)
+    expect(result.has("/another/path")).toBe(true)
+  })
+
+  test("deduplicates paths across multiple messages", () => {
+    const part1 = readToolPart({
+      id: "p1",
+      messageID: "m1",
+      status: "completed",
+      loaded: ["/project/AGENTS.md"],
+    })
+    const part2 = readToolPart({
+      id: "p2",
+      messageID: "m2",
+      status: "completed",
+      loaded: ["/project/AGENTS.md", "/project/lib/AGENTS.md"],
+    })
+    const result = InstructionPrompt.loaded([makeUserMsg("m1", [part1]), makeUserMsg("m2", [part2])])
+    expect(result.size).toBe(2)
+    expect(result.has("/project/AGENTS.md")).toBe(true)
+    expect(result.has("/project/lib/AGENTS.md")).toBe(true)
+  })
+})
+
+// ─── InstructionPrompt.resolve ──────────────────────────────────────────────
 
 describe("InstructionPrompt.resolve", () => {
   test("returns empty when AGENTS.md is at project root (already in systemPaths)", async () => {
diff --git a/packages/opencode/test/session/message-v2.test.ts b/packages/opencode/test/session/message-v2.test.ts
index e9c6cb729b..15aff2105d 100644
--- a/packages/opencode/test/session/message-v2.test.ts
+++ b/packages/opencode/test/session/message-v2.test.ts
@@ -896,3 +896,141 @@ describe("session.message-v2.fromError", () => {
     })
   })
 })
+
+// ─── filterCompacted ────────────────────────────────────────────────────────
+
+describe("session.message-v2.filterCompacted", () => {
+  // Helper to create a user message with optional compaction part
+  function userMsg(id: string, opts?: { compaction?: boolean }): MessageV2.WithParts {
+    const parts: MessageV2.Part[] = []
+    if (opts?.compaction) {
+      parts.push({
+        ...basePart(id, `${id}-compact`),
+        type: "compaction",
+        auto: true,
+      } as MessageV2.Part)
+    }
+    parts.push({
+      ...basePart(id, `${id}-text`),
+      type: "text",
+      content: `user message ${id}`,
+    } as MessageV2.Part)
+    return {
+      info: { ...userInfo(id) } as MessageV2.User,
+      parts,
+    }
+  }
+
+  // Helper to create an assistant message
+  function assistantMsg(
+    id: string,
+    parentID: string,
+    opts?: { summary?: boolean; finish?: string; error?: boolean },
+  ): MessageV2.WithParts {
+    const info = assistantInfo(id, parentID) as any
+    if (opts?.summary) info.summary = true
+    if (opts?.finish) info.finish = opts.finish
+    if (opts?.error) {
+      info.error = { name: "UnknownError", data: { message: "something went wrong" } }
+    }
+    return {
+      info: info as MessageV2.Assistant,
+      parts: [
+        {
+          ...basePart(id, `${id}-text`),
+          type: "text",
+          content: `assistant response ${id}`,
+        } as MessageV2.Part,
+      ],
+    }
+  }
+
+  async function* toStream(msgs: MessageV2.WithParts[]) {
+    for (const msg of msgs) yield msg
+  }
+
+  test("returns all messages reversed when no compaction point exists", async () => {
+    const u1 = userMsg("u1")
+    const a1 = assistantMsg("a1", "u1", { summary: true, finish: "stop" })
+    const u2 = userMsg("u2")
+    const a2 = assistantMsg("a2", "u2", { summary: true, finish: "stop" })
+
+    // Stream is newest-first (reverse chronological, as the DB query returns)
+    const result = await MessageV2.filterCompacted(toStream([a2, u2, a1, u1]))
+
+    // Reversed: oldest-first
+    expect(result.length).toBe(4)
+    expect(result[0].info.id).toBe("u1")
+    expect(result[1].info.id).toBe("a1")
+    expect(result[2].info.id).toBe("u2")
+    expect(result[3].info.id).toBe("a2")
+  })
+
+  test("stops at compaction boundary and returns slice reversed", async () => {
+    // Stream (newest-first): a3, u3, a2, u2(compacted), a1, u1
+    // u2 has a compaction part AND a1 completed successfully with parentID=u1
+    // But a2 completed with parentID=u2, so u2 is in completed set
+    const u1 = userMsg("u1")
+    const a1 = assistantMsg("a1", "u1", { summary: true, finish: "stop" })
+    const u2 = userMsg("u2", { compaction: true })
+    const a2 = assistantMsg("a2", "u2", { summary: true, finish: "stop" })
+    const u3 = userMsg("u3")
+    const a3 = assistantMsg("a3", "u3", { summary: true, finish: "stop" })
+
+    const result = await MessageV2.filterCompacted(toStream([a3, u3, a2, u2, a1, u1]))
+
+    // Should stop at u2 (has compaction part and is in completed set via a2)
+    // Collected: [a3, u3, a2, u2] then reversed
+    expect(result.length).toBe(4)
+    expect(result[0].info.id).toBe("u2")
+    expect(result[1].info.id).toBe("a2")
+    expect(result[2].info.id).toBe("u3")
+    expect(result[3].info.id).toBe("a3")
+  })
+
+  test("does not stop at user message with compaction part if no matching assistant completion", async () => {
+    // u2 has compaction part but no assistant completed with parentID=u2
+    const u1 = userMsg("u1")
+    const a1 = assistantMsg("a1", "u1", { summary: true, finish: "stop" })
+    const u2 = userMsg("u2", { compaction: true })
+    // a2 is still running (no summary, no finish)
+    const a2 = assistantMsg("a2", "u2")
+    const u3 = userMsg("u3")
+
+    const result = await MessageV2.filterCompacted(toStream([u3, a2, u2, a1, u1]))
+
+    // Should NOT stop at u2 because u2 is not in the completed set
+    // All 5 messages returned, reversed
+    expect(result.length).toBe(5)
+    expect(result[0].info.id).toBe("u1")
+    expect(result[4].info.id).toBe("u3")
+  })
+
+  test("errored assistant does not mark parent as completed", async () => {
+    // a2 has error, summary, finish — but error should prevent marking u2 as completed
+    const u1 = userMsg("u1")
+    const a1 = assistantMsg("a1", "u1", { summary: true, finish: "stop" })
+    const u2 = userMsg("u2", { compaction: true })
+    const a2 = assistantMsg("a2", "u2", { summary: true, finish: "stop", error: true })
+    const u3 = userMsg("u3")
+
+    const result = await MessageV2.filterCompacted(toStream([u3, a2, u2, a1, u1]))
+
+    // Should NOT stop at u2 because a2 has an error
+    expect(result.length).toBe(5)
+    expect(result[0].info.id).toBe("u1")
+    expect(result[4].info.id).toBe("u3")
+  })
+
+  test("requires both compaction part and completed set membership to stop", async () => {
+    // a1 completes for u1, so u1 is in completed set, but u1 has NO compaction part
+    const u1 = userMsg("u1") // no compaction part
+    const a1 = assistantMsg("a1", "u1", { summary: true, finish: "stop" })
+    const u2 = userMsg("u2")
+
+    const result = await MessageV2.filterCompacted(toStream([u2, a1, u1]))
+
+    // Should NOT stop at u1 because u1 has no compaction part
+    expect(result.length).toBe(3)
+  })
+})