fix: skip slow file processing before write on large files

packages/opencode/src/cli/cmd/tui/routes/session/index.tsx

@@ -1854,20 +1854,26 @@ function Write(props: ToolProps<typeof WriteTool>) {
     if (!props.input.content) return ""
     return props.input.content
   })
+  const truncated = createMemo(() => Boolean(props.metadata.truncated))
 
   return (
     <Switch>
       <Match when={props.metadata.diagnostics !== undefined}>
         <BlockTool title={"# Wrote " + normalizePath(props.input.filePath!)} part={props.part}>
-          <line_number fg={theme.textMuted} minWidth={3} paddingRight={1}>
-            <code
-              conceal={false}
-              fg={theme.text}
-              filetype={filetype(props.input.filePath!)}
-              syntaxStyle={syntax()}
-              content={code()}
-            />
-          </line_number>
+          <Show
+            when={!truncated()}
+            fallback={<text fg={theme.textMuted}>(large file — content not shown)</text>}
+          >
+            <line_number fg={theme.textMuted} minWidth={3} paddingRight={1}>
+              <code
+                conceal={false}
+                fg={theme.text}
+                filetype={filetype(props.input.filePath!)}
+                syntaxStyle={syntax()}
+                content={code()}
+              />
+            </line_number>
+          </Show>
           <Diagnostics diagnostics={props.metadata.diagnostics} filePath={props.input.filePath ?? ""} />
         </BlockTool>
       </Match>

packages/opencode/src/cli/cmd/tui/routes/session/permission.tsx

@@ -55,6 +55,9 @@ function EditBody(props: { request: PermissionRequest }) {
 
   const filepath = createMemo(() => (props.request.metadata?.filepath as string) ?? "")
   const diff = createMemo(() => (props.request.metadata?.diff as string) ?? "")
+  const truncated = createMemo(() => Boolean(props.request.metadata?.truncated))
+  const additions = createMemo(() => (props.request.metadata?.additions as number) ?? 0)
+  const deletions = createMemo(() => (props.request.metadata?.deletions as number) ?? 0)
 
   const view = createMemo(() => {
     const diffStyle = config.diff_style
@@ -101,7 +104,11 @@ function EditBody(props: { request: PermissionRequest }) {
       </Show>
       <Show when={!diff()}>
         <box paddingLeft={1}>
-          <text fg={theme.textMuted}>No diff provided</text>
+          <text fg={theme.textMuted}>
+            {truncated()
+              ? `Large file — diff omitted (+${additions()} / -${deletions()} lines)`
+              : "No diff provided"}
+          </text>
         </box>
       </Show>
     </box>

packages/opencode/src/tool/apply_patch.ts

@@ -6,9 +6,8 @@ import { Bus } from "../bus"
 import { FileWatcher } from "../file/watcher"
 import { Instance } from "../project/instance"
 import { Patch } from "../patch"
-import { createTwoFilesPatch, diffLines } from "diff"
 import { assertExternalDirectoryEffect } from "./external-directory"
-import { trimDiff } from "./edit"
+import { buildDisplayDiff, LARGE_FILE_FORMAT_BYTES } from "./edit"
 import { LSP } from "../lsp"
 import { AppFileSystem } from "../filesystem"
 import DESCRIPTION from "./apply_patch.txt"
@@ -59,6 +58,7 @@ export const ApplyPatchTool = Tool.define(
         diff: string
         additions: number
         deletions: number
+        truncated: boolean
       }> = []
 
       let totalDiff = ""
@@ -72,26 +72,20 @@ export const ApplyPatchTool = Tool.define(
             const oldContent = ""
             const newContent =
               hunk.contents.length === 0 || hunk.contents.endsWith("\n") ? hunk.contents : `${hunk.contents}\n`
-            const diff = trimDiff(createTwoFilesPatch(filePath, filePath, oldContent, newContent))
-
-            let additions = 0
-            let deletions = 0
-            for (const change of diffLines(oldContent, newContent)) {
-              if (change.added) additions += change.count || 0
-              if (change.removed) deletions += change.count || 0
-            }
+            const display = buildDisplayDiff(filePath, oldContent, newContent)
 
             fileChanges.push({
               filePath,
               oldContent,
               newContent,
               type: "add",
-              diff,
-              additions,
-              deletions,
+              diff: display.diff,
+              additions: display.additions,
+              deletions: display.deletions,
+              truncated: display.truncated,
             })
 
-            totalDiff += diff + "\n"
+            totalDiff += display.diff + "\n"
             break
           }
 
@@ -115,14 +109,7 @@ export const ApplyPatchTool = Tool.define(
               return yield* Effect.fail(new Error(`apply_patch verification failed: ${error}`))
             }
 
-            const diff = trimDiff(createTwoFilesPatch(filePath, filePath, oldContent, newContent))
-
-            let additions = 0
-            let deletions = 0
-            for (const change of diffLines(oldContent, newContent)) {
-              if (change.added) additions += change.count || 0
-              if (change.removed) deletions += change.count || 0
-            }
+            const display = buildDisplayDiff(filePath, oldContent, newContent)
 
             const movePath = hunk.move_path ? path.resolve(Instance.directory, hunk.move_path) : undefined
             yield* assertExternalDirectoryEffect(ctx, movePath)
@@ -133,34 +120,34 @@ export const ApplyPatchTool = Tool.define(
               newContent,
               type: hunk.move_path ? "move" : "update",
               movePath,
-              diff,
-              additions,
-              deletions,
+              diff: display.diff,
+              additions: display.additions,
+              deletions: display.deletions,
+              truncated: display.truncated,
             })
 
-            totalDiff += diff + "\n"
+            totalDiff += display.diff + "\n"
             break
           }
 
           case "delete": {
             const contentToDelete = yield* afs
               .readFileString(filePath)
               .pipe(Effect.catch((error) => Effect.fail(new Error(`apply_patch verification failed: ${error}`))))
-            const deleteDiff = trimDiff(createTwoFilesPatch(filePath, filePath, contentToDelete, ""))
-
-            const deletions = contentToDelete.split("\n").length
+            const display = buildDisplayDiff(filePath, contentToDelete, "")
 
             fileChanges.push({
               filePath,
               oldContent: contentToDelete,
               newContent: "",
               type: "delete",
-              diff: deleteDiff,
+              diff: display.diff,
               additions: 0,
-              deletions,
+              deletions: display.truncated ? display.deletions : contentToDelete.split("\n").length,
+              truncated: display.truncated,
             })
 
-            totalDiff += deleteDiff + "\n"
+            totalDiff += display.diff + "\n"
             break
           }
         }
@@ -175,7 +162,9 @@ export const ApplyPatchTool = Tool.define(
         additions: change.additions,
         deletions: change.deletions,
         movePath: change.movePath,
+        truncated: change.truncated,
       }))
+      const anyTruncated = fileChanges.some((c) => c.truncated)
 
       // Check permissions if needed
       const relativePaths = fileChanges.map((c) => path.relative(Instance.worktree, c.filePath).replaceAll("\\", "/"))
@@ -187,6 +176,7 @@ export const ApplyPatchTool = Tool.define(
           filepath: relativePaths.join(", "),
           diff: totalDiff,
           files,
+          truncated: anyTruncated,
         },
       })
 
@@ -226,7 +216,10 @@ export const ApplyPatchTool = Tool.define(
         }
 
         if (edited) {
-          yield* format.file(edited)
+          const editedSize = Buffer.byteLength(change.newContent, "utf8")
+          if (editedSize <= LARGE_FILE_FORMAT_BYTES) {
+            yield* format.file(edited)
+          }
           yield* bus.publish(File.Event.Edited, { file: edited })
         }
       }
@@ -236,13 +229,17 @@ export const ApplyPatchTool = Tool.define(
         yield* bus.publish(FileWatcher.Event.Updated, update)
       }
 
-      // Notify LSP of file changes and collect diagnostics
-      for (const change of fileChanges) {
-        if (change.type === "delete") continue
-        const target = change.movePath ?? change.filePath
-        yield* lsp.touchFile(target, true)
+      // Notify LSP of file changes and collect diagnostics (skip for very large files)
+      const skipLsp = fileChanges.some((c) => Buffer.byteLength(c.newContent, "utf8") > LARGE_FILE_FORMAT_BYTES)
+      let diagnostics: Record<string, import("../lsp/client").LSPClient.Diagnostic[]> = {}
+      if (!skipLsp) {
+        for (const change of fileChanges) {
+          if (change.type === "delete") continue
+          const target = change.movePath ?? change.filePath
+          yield* lsp.touchFile(target, true)
+        }
+        diagnostics = yield* lsp.diagnostics()
       }
-      const diagnostics = yield* lsp.diagnostics()
 
       // Generate output summary
       const summaryLines = fileChanges.map((change) => {
@@ -272,6 +269,7 @@ export const ApplyPatchTool = Tool.define(
           diff: totalDiff,
           files,
           diagnostics,
+          truncated: anyTruncated,
         },
         output,
       }

packages/opencode/src/tool/edit.ts

@@ -612,6 +612,39 @@ export const ContextAwareReplacer: Replacer = function* (content, find) {
   }
 }
 
+export const LARGE_FILE_DIFF_BYTES = 256 * 1024
+export const LARGE_FILE_FORMAT_BYTES = 2 * 1024 * 1024
+
+export interface DisplayDiff {
+  diff: string
+  truncated: boolean
+  additions: number
+  deletions: number
+}
+
+export function buildDisplayDiff(filepath: string, oldContent: string, newContent: string): DisplayDiff {
+  const oldSize = Buffer.byteLength(oldContent, "utf8")
+  const newSize = Buffer.byteLength(newContent, "utf8")
+  if (oldSize > LARGE_FILE_DIFF_BYTES || newSize > LARGE_FILE_DIFF_BYTES) {
+    const oldLines = oldContent ? oldContent.split("\n").length : 0
+    const newLines = newContent ? newContent.split("\n").length : 0
+    return {
+      diff: "",
+      truncated: true,
+      additions: Math.max(0, newLines - oldLines),
+      deletions: Math.max(0, oldLines - newLines),
+    }
+  }
+  let additions = 0
+  let deletions = 0
+  for (const change of diffLines(oldContent, newContent)) {
+    if (change.added) additions += change.count || 0
+    if (change.removed) deletions += change.count || 0
+  }
+  const diff = trimDiff(createTwoFilesPatch(filepath, filepath, oldContent, newContent))
+  return { diff, truncated: false, additions, deletions }
+}
+
 export function trimDiff(diff: string): string {
   const lines = diff.split("\n")
   const contentLines = lines.filter(

packages/opencode/src/tool/write.ts

@@ -3,7 +3,7 @@ import * as path from "path"
 import { Effect } from "effect"
 import { Tool } from "./tool"
 import { LSP } from "../lsp"
-import { createTwoFilesPatch } from "diff"
+import { LSPClient } from "../lsp/client"
 import DESCRIPTION from "./write.txt"
 import { Bus } from "../bus"
 import { File } from "../file"
@@ -12,7 +12,7 @@ import { Format } from "../format"
 import { FileTime } from "../file/time"
 import { AppFileSystem } from "../filesystem"
 import { Instance } from "../project/instance"
-import { trimDiff } from "./edit"
+import { buildDisplayDiff, LARGE_FILE_FORMAT_BYTES } from "./edit"
 import { assertExternalDirectoryEffect } from "./external-directory"
 
 const MAX_PROJECT_DIAGNOSTICS_FILES = 5
@@ -43,19 +43,24 @@ export const WriteTool = Tool.define(
           const contentOld = exists ? yield* fs.readFileString(filepath) : ""
           if (exists) yield* filetime.assert(ctx.sessionID, filepath)
 
-          const diff = trimDiff(createTwoFilesPatch(filepath, filepath, contentOld, params.content))
+          const display = buildDisplayDiff(filepath, contentOld, params.content)
           yield* ctx.ask({
             permission: "edit",
             patterns: [path.relative(Instance.worktree, filepath)],
             always: ["*"],
             metadata: {
               filepath,
-              diff,
+              diff: display.diff,
+              truncated: display.truncated,
+              additions: display.additions,
+              deletions: display.deletions,
             },
           })
 
           yield* fs.writeWithDirs(filepath, params.content)
-          yield* format.file(filepath)
+          const newSize = Buffer.byteLength(params.content, "utf8")
+          const skipHeavy = newSize > LARGE_FILE_FORMAT_BYTES
+          if (!skipHeavy) yield* format.file(filepath)
           yield* bus.publish(File.Event.Edited, { file: filepath })
           yield* bus.publish(FileWatcher.Event.Updated, {
             file: filepath,
@@ -64,21 +69,24 @@ export const WriteTool = Tool.define(
           yield* filetime.read(ctx.sessionID, filepath)
 
           let output = "Wrote file successfully."
-          yield* lsp.touchFile(filepath, true)
-          const diagnostics = yield* lsp.diagnostics()
-          const normalizedFilepath = AppFileSystem.normalizePath(filepath)
-          let projectDiagnosticsCount = 0
-          for (const [file, issues] of Object.entries(diagnostics)) {
-            const current = file === normalizedFilepath
-            if (!current && projectDiagnosticsCount >= MAX_PROJECT_DIAGNOSTICS_FILES) continue
-            const block = LSP.Diagnostic.report(current ? filepath : file, issues)
-            if (!block) continue
-            if (current) {
-              output += `\n\nLSP errors detected in this file, please fix:\n${block}`
-              continue
+          let diagnostics: Record<string, LSPClient.Diagnostic[]> = {}
+          if (!skipHeavy) {
+            yield* lsp.touchFile(filepath, true)
+            diagnostics = yield* lsp.diagnostics()
+            const normalizedFilepath = AppFileSystem.normalizePath(filepath)
+            let projectDiagnosticsCount = 0
+            for (const [file, issues] of Object.entries(diagnostics)) {
+              const current = file === normalizedFilepath
+              if (!current && projectDiagnosticsCount >= MAX_PROJECT_DIAGNOSTICS_FILES) continue
+              const block = LSP.Diagnostic.report(current ? filepath : file, issues)
+              if (!block) continue
+              if (current) {
+                output += `\n\nLSP errors detected in this file, please fix:\n${block}`
+                continue
+              }
+              projectDiagnosticsCount++
+              output += `\n\nLSP errors detected in other files:\n${block}`
             }
-            projectDiagnosticsCount++
-            output += `\n\nLSP errors detected in other files:\n${block}`
           }
 
           return {
@@ -87,6 +95,7 @@ export const WriteTool = Tool.define(
               diagnostics,
               filepath,
               exists: exists,
+              truncated: display.truncated,
             },
             output,
           }