apply_patch forces a trailing newline onto files that lacked one #45912

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1. github-actions

   assigned

   kitlangton

   on Aug 28, 2026
2. github-actions commented on Aug 28, 2026

   

   github-actionsBot

   on Aug 28, 2026 – with GitHub Actions

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   This issue might be a duplicate of (or closely related to) an existing issue. Please check:

   • apply_patch deletes the final blank line of files that end with one #42081: Reports the inverse behavior in the same function — derive() in packages/core/src/patch.ts drops a trailing blank line from files that end with \n\n. Both issues trace back to the same EOF-sentinel logic in derive() and likely need to be fixed together.
3. maplemuse commented on Sep 1, 2026

   

   maplemuse

   on Sep 1, 2026

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   I work in a large repo where we have a .editorconfig setting which prohibits trailing newlines at the end of the file. When we use our formatter, it then triggers on every file apply_patch is applied to, which adds significant churn. Is there a way to ignore changes to the end of the file if none were made, or to otherwise follow repository conventions?

   👍React with 👍1Reacted by fcrdicecco
4. opencodejr commented on Oct 28, 2026

   

   opencodejrBot

   on Oct 28, 2026

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   Thanks for the clear report. I could reproduce this.

   Steps: a project with f.txt containing line1\nline2\nline3 and no final newline, and a simulated GPT model that calls the patch tool to change only line1 to LINE1. After the patch:

   • the tool's own "Patched f.txt" diff shows line3 removed and added again;
   • git diff shows \ No newline at end of file only on the old side;
   • od -c shows the file now ends with 3 \n.

   The recording and screenshots below show this, and the script below reproduces it. It happens on 2.2.0 and still happens on the latest dev (506ac20). The cause is the line in derive() (now in packages/util/src/patch.ts) that always adds a final newline, whatever the original file ended with.

   Related:

   • fix(core): preserve missing final newline in apply_patch #59154: open PR that targets this issue, keeping the original ending unless the patch reaches the end of the file
   • apply_patch deletes the final blank line of files that end with one #42081: the reverse case, where a final blank line was dropped (closed)
   • apply_patch turns CRLF files into mixed line endings #45926: apply_patch mixing line endings in CRLF files

   recording.mp4

   

   

   Reproduction script (drive.ts)

   // Repro for anomalyco/opencode#45912: the patch (apply_patch) tool adds a trailing
   // newline to a file that had none, even though the patch only edits line 1.
   // Run: OPENCODE_DRIVE_MEDIA_DIR=/workspace/media opencode-drive run drive.ts
   // (set OC_DEV=/path/to/opencode/checkout to run from source)
   import { Effect, Stream } from "effect"
   import { Llm, OpenCodeDriver } from "opencode-drive"
   
   const patchText = "*** Begin Patch\n*** Update File: f.txt\n@@\n-line1\n+LINE1\n*** End Patch"
   const check = "git diff f.txt; od -c f.txt"
   
   export default OpenCodeDriver.use(
     {
       ...(process.env.OC_DEV ? { opencode: { dev: process.env.OC_DEV } } : {}),
       tui: { recording: true },
       // f.txt has NO trailing newline
       project: { git: true, files: { "f.txt": "line1\nline2\nline3" } },
     },
     ({ ui, llm }) =>
       Effect.gen(function* () {
         let step = 0
         yield* llm.serve((request: any) => {
           if (!request.body?.tools?.length || JSON.stringify(request.body?.messages ?? "").includes("You name conversations")) return Stream.make(Llm.text("Patch EOF newline")) // title request
           step++
           if (step === 1)
             return Stream.make(Llm.toolCall({ index: 0, id: "call_patch", name: "patch", input: { patchText } }), Llm.finish("tool-calls"))
           if (step === 2)
             return Stream.make(
               Llm.toolCall({ index: 0, id: "call_check", name: "shell", input: { command: check, description: "Show diff and bytes" } }),
               Llm.finish("tool-calls"),
             )
           return Stream.make(Llm.text("Done checking."))
         })
         yield* ui.submit("Uppercase line1 in f.txt")
         yield* ui.waitFor("Done checking.")
         yield* Effect.sleep("2 seconds")
         yield* ui.screenshot("after-patch")
       }),
   )

   Run it with opencode-drive: opencode-drive run ./drive.ts. It drives opencode from your PATH; set OC_DEV to the path of an OpenCode checkout to run that from source instead.
5. opencodejr

   added

   reproduced

   on Oct 28, 2026