From 8e7abbede7ae1958e81af31286c90978744fc1bc Mon Sep 17 00:00:00 2001
From: Rohan Poudel <yitsmerohan@gmail.com>
Date: Sun, 21 Jun 2026 22:13:10 +0545
Subject: [PATCH] fix(loop-detection): add pre-execution tool dedup and reduce
 threshold to 2 (#1162)

---
 .../src/session/prompt/text-loop-recovery.ts  |  2 +-
 packages/opencode/src/tool/tool.ts            | 28 +++++++++++++++++++
 .../test/session/text-loop-detection.test.ts  | 15 +++++-----
 3 files changed, 36 insertions(+), 9 deletions(-)

diff --git a/packages/opencode/src/session/prompt/text-loop-recovery.ts b/packages/opencode/src/session/prompt/text-loop-recovery.ts
index 6b96d6fac..22b6f48e7 100644
--- a/packages/opencode/src/session/prompt/text-loop-recovery.ts
+++ b/packages/opencode/src/session/prompt/text-loop-recovery.ts
@@ -1,5 +1,5 @@
 export const TEXT_LOOP_BUFFER_SIZE = 5
-export const TEXT_LOOP_TRIGGER_COUNT = 3
+export const TEXT_LOOP_TRIGGER_COUNT = 2
 export const TEXT_LOOP_MAX_RECOVERY = 2
 
 export function normalizeForLoopDetection(text: string): string {
diff --git a/packages/opencode/src/tool/tool.ts b/packages/opencode/src/tool/tool.ts
index c2a406e8d..27fa06ac6 100644
--- a/packages/opencode/src/tool/tool.ts
+++ b/packages/opencode/src/tool/tool.ts
@@ -107,6 +107,34 @@ function wrap<Parameters extends z.ZodType, Result extends Metadata>(
           ...(ctx.callID ? { "tool.call_id": ctx.callID } : {}),
         }
         return Effect.gen(function* () {
+          // Pre-execution dedup (Issue #1162)
+          let duplicatePart: any | undefined
+          for (let i = ctx.messages.length - 1; i >= 0; i--) {
+            const msg = ctx.messages[i]
+            if (msg.info.role === "user") break
+            const toolParts = msg.parts.filter(
+              (p: any) =>
+                p.type === "tool" &&
+                p.tool === id &&
+                p.state &&
+                p.state.status === "completed" &&
+                JSON.stringify(p.state.input) === JSON.stringify(args)
+            )
+            if (toolParts.length > 0) {
+              duplicatePart = toolParts[toolParts.length - 1]
+              break
+            }
+          }
+
+          if (duplicatePart && duplicatePart.state && duplicatePart.state.status === "completed") {
+            return {
+              title: duplicatePart.state.title,
+              metadata: duplicatePart.state.metadata as Result,
+              output: duplicatePart.state.output,
+              attachments: duplicatePart.state.attachments,
+            }
+          }
+
           yield* Effect.try({
             try: () => toolInfo.parameters.parse(args),
             catch: (error) => {
diff --git a/packages/opencode/test/session/text-loop-detection.test.ts b/packages/opencode/test/session/text-loop-detection.test.ts
index ea1234d28..9b53f630d 100644
--- a/packages/opencode/test/session/text-loop-detection.test.ts
+++ b/packages/opencode/test/session/text-loop-detection.test.ts
@@ -72,12 +72,11 @@ describe("detectTextLoop", () => {
 })
 
 describe("text loop detection integration logic", () => {
-  test("full detection flow: 3 identical triggers detection", () => {
+  test("full detection flow: 2 identical triggers detection", () => {
     const buffer: string[] = []
     const texts = [
       "Let me check if one was already created earlier and update it.",
       "Let me check if one was already created earlier and update it.",
-      "Let me check if one was already created earlier and update it.",
     ]
 
     let triggered = false
@@ -126,8 +125,8 @@ describe("text loop detection integration logic", () => {
     let recoveryAttempts = 0
     const repeatedText = "The user wants me to create a ChangeLog file."
 
-    // First 3 identical → trigger #1
-    for (let i = 0; i < 3; i++) {
+    // First 2 identical → trigger #1
+    for (let i = 0; i < 2; i++) {
       buffer.push(normalizeForLoopDetection(repeatedText))
     }
     expect(detectTextLoop(buffer, TEXT_LOOP_TRIGGER_COUNT)).toBe(true)
@@ -146,7 +145,7 @@ describe("text loop detection integration logic", () => {
     buffer.length = 0
 
     // Third trigger would exceed max
-    for (let i = 0; i < 3; i++) {
+    for (let i = 0; i < 2; i++) {
       buffer.push(normalizeForLoopDetection(repeatedText))
     }
     expect(detectTextLoop(buffer, TEXT_LOOP_TRIGGER_COUNT)).toBe(true)
@@ -159,8 +158,8 @@ describe("text loop detection integration logic", () => {
     const repeatedText = "I am stuck in a loop"
     const differentText = "OK I will try something else"
 
-    // 3 identical → trigger
-    for (let i = 0; i < 3; i++) {
+    // 2 identical → trigger
+    for (let i = 0; i < 2; i++) {
       buffer.push(normalizeForLoopDetection(repeatedText))
     }
     expect(detectTextLoop(buffer, TEXT_LOOP_TRIGGER_COUNT)).toBe(true)
@@ -179,7 +178,7 @@ describe("text loop detection integration logic", () => {
 
   test("constants have expected values", () => {
     expect(TEXT_LOOP_BUFFER_SIZE).toBe(5)
-    expect(TEXT_LOOP_TRIGGER_COUNT).toBe(3)
+    expect(TEXT_LOOP_TRIGGER_COUNT).toBe(2)
     expect(TEXT_LOOP_MAX_RECOVERY).toBe(2)
   })
 })