refactor(snapshot): store unified patches in file diffs (#21244)

Co-authored-by: Adam <2363879+adamdotdevin@users.noreply.github.com>

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

@@ -2124,7 +2124,7 @@ function ApplyPatch(props: ToolProps<typeof ApplyPatchTool>) {
                   </text>
                 }
               >
-                <Diff diff={file.diff} filePath={file.filePath} />
+                <Diff diff={file.patch} filePath={file.filePath} />
                 <Diagnostics diagnostics={props.metadata.diagnostics} filePath={file.movePath ?? file.filePath} />
               </Show>
             </BlockTool>

packages/opencode/src/project/vcs.ts

@@ -1,4 +1,5 @@
 import { Effect, Layer, ServiceMap, Stream } from "effect"
+import { formatPatch, structuredPatch } from "diff"
 import path from "path"
 import { Bus } from "@/bus"
 import { BusEvent } from "@/bus/bus-event"
@@ -7,7 +8,6 @@ import { makeRuntime } from "@/effect/run-service"
 import { AppFileSystem } from "@/filesystem"
 import { FileWatcher } from "@/file/watcher"
 import { Git } from "@/git"
-import { Snapshot } from "@/snapshot"
 import { Log } from "@/util/log"
 import { Instance } from "./instance"
 import z from "zod"
@@ -49,6 +49,8 @@ export namespace Vcs {
     map: Map<string, { additions: number; deletions: number }>,
   ) {
     const base = ref ? yield* git.prefix(cwd) : ""
+    const patch = (file: string, before: string, after: string) =>
+      formatPatch(structuredPatch(file, file, before, after, "", "", { context: Number.MAX_SAFE_INTEGER }))
     const next = yield* Effect.forEach(
       list,
       (item) =>
@@ -58,12 +60,11 @@ export namespace Vcs {
           const stat = map.get(item.file)
           return {
             file: item.file,
-            before,
-            after,
+            patch: patch(item.file, before, after),
             additions: stat?.additions ?? (item.status === "added" ? count(after) : 0),
             deletions: stat?.deletions ?? (item.status === "deleted" ? count(before) : 0),
             status: item.status,
-          } satisfies Snapshot.FileDiff
+          } satisfies FileDiff
         }),
       { concurrency: 8 },
     )
@@ -125,11 +126,24 @@ export namespace Vcs {
     })
   export type Info = z.infer<typeof Info>
 
+  export const FileDiff = z
+    .object({
+      file: z.string(),
+      patch: z.string(),
+      additions: z.number(),
+      deletions: z.number(),
+      status: z.enum(["added", "deleted", "modified"]).optional(),
+    })
+    .meta({
+      ref: "VcsFileDiff",
+    })
+  export type FileDiff = z.infer<typeof FileDiff>
+
   export interface Interface {
     readonly init: () => Effect.Effect<void>
     readonly branch: () => Effect.Effect<string | undefined>
     readonly defaultBranch: () => Effect.Effect<string | undefined>
-    readonly diff: (mode: Mode) => Effect.Effect<Snapshot.FileDiff[]>
+    readonly diff: (mode: Mode) => Effect.Effect<FileDiff[]>
   }
 
   interface State {

packages/opencode/src/server/instance.ts

@@ -154,7 +154,7 @@ export const InstanceRoutes = (upgrade: UpgradeWebSocket, app: Hono = new Hono()
             description: "VCS diff",
             content: {
               "application/json": {
-                schema: resolver(Snapshot.FileDiff.array()),
+                schema: resolver(Vcs.FileDiff.array()),
               },
             },
           },

packages/opencode/src/share/share-next.ts

@@ -59,7 +59,7 @@ export namespace ShareNext {
       }
     | {
         type: "session_diff"
-        data: SDK.FileDiff[]
+        data: SDK.SnapshotFileDiff[]
       }
     | {
         type: "model"

packages/opencode/src/snapshot/index.ts

@@ -1,6 +1,6 @@
-import { NodeFileSystem, NodePath } from "@effect/platform-node"
 import { Cause, Duration, Effect, Layer, Schedule, Semaphore, ServiceMap, Stream } from "effect"
 import { ChildProcess, ChildProcessSpawner } from "effect/unstable/process"
+import { formatPatch, structuredPatch } from "diff"
 import path from "path"
 import z from "zod"
 import * as CrossSpawnSpawner from "@/effect/cross-spawn-spawner"
@@ -22,14 +22,13 @@ export namespace Snapshot {
   export const FileDiff = z
     .object({
       file: z.string(),
-      before: z.string(),
-      after: z.string(),
+      patch: z.string(),
       additions: z.number(),
       deletions: z.number(),
       status: z.enum(["added", "deleted", "modified"]).optional(),
     })
     .meta({
-      ref: "FileDiff",
+      ref: "SnapshotFileDiff",
     })
   export type FileDiff = z.infer<typeof FileDiff>
 
@@ -521,8 +520,6 @@ export namespace Snapshot {
                     const map = new Map<string, { before: string; after: string }>()
                     const dec = new TextDecoder()
                     let i = 0
-                    // Parse the default `git cat-file --batch` stream: one header line,
-                    // then exactly `size` bytes of blob content, then a trailing newline.
                     for (const ref of refs) {
                       let end = i
                       while (end < out.length && out[end] !== 10) end += 1
@@ -620,8 +617,9 @@ export namespace Snapshot {
                     ]
                   })
                 const step = 100
+                const patch = (file: string, before: string, after: string) =>
+                  formatPatch(structuredPatch(file, file, before, after, "", "", { context: Number.MAX_SAFE_INTEGER }))
 
-                // Keep batches bounded so a large diff does not buffer every blob at once.
                 for (let i = 0; i < rows.length; i += step) {
                   const run = rows.slice(i, i + step)
                   const text = yield* load(run)
@@ -631,8 +629,7 @@ export namespace Snapshot {
                     const [before, after] = row.binary ? ["", ""] : text ? [hit.before, hit.after] : yield* show(row)
                     result.push({
                       file: row.file,
-                      before,
-                      after,
+                      patch: row.binary ? "" : patch(row.file, before, after),
                       additions: row.additions,
                       deletions: row.deletions,
                       status: row.status,

packages/opencode/src/tool/apply_patch.ts

@@ -164,9 +164,7 @@ export const ApplyPatchTool = Tool.define("apply_patch", {
       filePath: change.filePath,
       relativePath: path.relative(Instance.worktree, change.movePath ?? change.filePath).replaceAll("\\", "/"),
       type: change.type,
-      diff: change.diff,
-      before: change.oldContent,
-      after: change.newContent,
+      patch: change.diff,
       additions: change.additions,
       deletions: change.deletions,
       movePath: change.movePath,

packages/opencode/src/tool/edit.ts

@@ -123,8 +123,7 @@ export const EditTool = Tool.define("edit", {
 
     const filediff: Snapshot.FileDiff = {
       file: filePath,
-      before: contentOld,
-      after: contentNew,
+      patch: diff,
       additions: 0,
       deletions: 0,
     }