feat(core): add embedded v2 session runtime and tool foundation (#30632)

packages/core/src/tool/edit.ts

@@ -0,0 +1,169 @@
+/**
+ * Model-facing V2 exact-edit leaf. Relative paths resolve within the active
+ * Location. Absolute paths inside that Location are accepted, while explicit
+ * absolute external paths retain mutation capability through a separate
+ * external_directory approval before edit approval. Named project references
+ * are read-oriented and deliberately are not accepted by mutation tools.
+ */
+export * as EditTool from "./edit"
+
+import { Tool, ToolFailure, toolText } from "@opencode-ai/llm"
+import { Cause, Effect, Layer, Schema } from "effect"
+import { FileMutation } from "../file-mutation"
+import { FSUtil } from "../fs-util"
+import { LocationMutation } from "../location-mutation"
+import { ToolRegistry } from "../tool-registry"
+
+export const name = "edit"
+
+export const Parameters = Schema.Struct({
+  path: Schema.String.annotate({
+    description:
+      "File path to edit. Relative paths resolve within the active Location. Absolute paths inside that Location are accepted; external absolute paths require external_directory approval. Named project references are read-oriented and are not accepted.",
+  }),
+  oldString: Schema.String.annotate({ description: "Exact text to replace" }),
+  newString: Schema.String.annotate({ description: "Replacement text, which must differ from oldString" }),
+  replaceAll: Schema.Boolean.pipe(Schema.optional).annotate({
+    description: "Replace all exact occurrences of oldString (default false)",
+  }),
+})
+
+export const Success = Schema.Struct({
+  operation: Schema.Literal("write"),
+  target: Schema.String,
+  resource: Schema.String,
+  existed: Schema.Boolean,
+  replacements: Schema.Number,
+})
+export type Success = typeof Success.Type
+
+const normalizeLineEndings = (text: string) => text.replaceAll("\r\n", "\n")
+const detectLineEnding = (text: string): "\n" | "\r\n" => (text.includes("\r\n") ? "\r\n" : "\n")
+const convertToLineEnding = (text: string, ending: "\n" | "\r\n") =>
+  ending === "\n" ? normalizeLineEndings(text) : normalizeLineEndings(text).replaceAll("\n", "\r\n")
+
+const splitBom = (text: string) =>
+  text.startsWith("\uFEFF") ? { bom: true, text: text.slice(1) } : { bom: false, text }
+const joinBom = (text: string, bom: boolean) => (bom ? `\uFEFF${text}` : text)
+const decodeUtf8 = (content: Uint8Array) => {
+  const bom = content[0] === 0xef && content[1] === 0xbb && content[2] === 0xbf
+  return { bom, content, text: new TextDecoder().decode(bom ? content.slice(3) : content) }
+}
+
+const countOccurrences = (content: string, search: string) => {
+  if (search === "") return content.length + 1
+  let count = 0
+  let offset = 0
+  while ((offset = content.indexOf(search, offset)) !== -1) {
+    count++
+    offset += search.length
+  }
+  return count
+}
+
+const previewLines = (value: string, prefix: "+" | "-") => {
+  const lines = normalizeLineEndings(value).split("\n")
+  const shown = lines.slice(0, 6).map((line) => `${prefix}${line.length > 240 ? `${line.slice(0, 240)}...` : line}`)
+  if (lines.length > shown.length) shown.push(`${prefix}...`)
+  return shown
+}
+
+export const toModelOutput = (output: Success, oldString: string, newString: string) =>
+  [
+    `Edited file successfully: ${output.resource}`,
+    `Replacements: ${output.replacements}`,
+    "```diff",
+    ...previewLines(oldString, "-"),
+    ...previewLines(newString, "+"),
+    "```",
+  ].join("\n")
+
+const definition = Tool.make({
+  description:
+    "Replace exact text in one file. Relative paths resolve within the active Location. Absolute paths inside the Location are accepted. Explicit external absolute paths require external_directory approval before edit approval. Named project references are read-oriented and are not accepted.",
+  parameters: Parameters,
+  success: Success,
+  toModelOutput: ({ parameters, output }) => [
+    toolText({ type: "text", text: toModelOutput(output, parameters.oldString, parameters.newString) }),
+  ],
+})
+
+/** Deferred V2 edit behavior and UX integrations remain visible at the model-facing seam. */
+// TODO: Port V1 fuzzy correction strategies only after exact-edit behavior is established: line-trimmed matching, block-anchor fallback, indentation correction, and similarity-threshold review.
+// TODO: Add formatter integration after V2 formatter runtime exists.
+// TODO: Publish watcher/file-edit events after V2 watcher integration exists.
+// TODO: Add snapshots / undo after design exists.
+// TODO: Add LSP notification and diagnostics after V2 LSP runtime exists.
+
+export const layer = Layer.effectDiscard(
+  Effect.gen(function* () {
+    const registry = yield* ToolRegistry.Service
+    const mutation = yield* LocationMutation.Service
+    const files = yield* FileMutation.Service
+    const fs = yield* FSUtil.Service
+
+    yield* registry.contribute((editor) =>
+      editor.set(name, {
+        tool: definition,
+        execute: ({ parameters, assertPermission }) => {
+          const unableToEdit = <A, E, R>(effect: Effect.Effect<A, E, R>) =>
+            effect.pipe(
+              Effect.catchCause((cause) => {
+                const error = Cause.squash(cause)
+                return Effect.fail(
+                  error instanceof FileMutation.StaleContentError
+                    ? new ToolFailure({ message: "File changed after permission approval. Read it again before editing." })
+                    : new ToolFailure({ message: `Unable to edit ${parameters.path}`, error }),
+                )
+              }),
+            )
+
+          return Effect.gen(function* () {
+            if (parameters.oldString === parameters.newString) {
+              return yield* new ToolFailure({ message: "No changes to apply: oldString and newString are identical." })
+            }
+            if (parameters.oldString === "") {
+              return yield* new ToolFailure({ message: "oldString must not be empty. Use write to create or overwrite a file." })
+            }
+
+            const plan = yield* unableToEdit(mutation.resolve({ path: parameters.path, kind: "file" }))
+            const external = plan.target.externalDirectory
+            if (external) {
+              yield* unableToEdit(assertPermission(LocationMutation.externalDirectoryPermission(external)))
+            }
+
+            yield* unableToEdit(assertPermission({ action: "edit", resources: [plan.target.resource], save: ["*"] }))
+            const readable = yield* unableToEdit(mutation.revalidate(plan))
+            const source = decodeUtf8(yield* unableToEdit(fs.readFile(readable.canonical)))
+            const ending = detectLineEnding(source.text)
+            const oldString = convertToLineEnding(parameters.oldString, ending)
+            const newString = convertToLineEnding(parameters.newString, ending)
+            const replacements = countOccurrences(source.text, oldString)
+            if (replacements === 0) {
+              return yield* new ToolFailure({
+                message:
+                  "Could not find oldString in the file. It must match exactly, including whitespace and indentation.",
+              })
+            }
+            if (replacements > 1 && parameters.replaceAll !== true) {
+              return yield* new ToolFailure({
+                message:
+                  "Found multiple exact matches for oldString. Provide more surrounding context or set replaceAll to true.",
+              })
+            }
+
+            const replaced =
+              parameters.replaceAll === true
+                ? source.text.replaceAll(oldString, newString)
+                : source.text.replace(oldString, newString)
+            const next = splitBom(replaced)
+            const result = yield* unableToEdit(
+              files.writeIfUnchanged({ plan, expected: source.content, content: joinBom(next.text, source.bom || next.bom) }),
+            )
+            return { ...result, replacements } satisfies Success
+          })
+        },
+      }),
+    )
+  }),
+)