feat: better image handling (auto resize & max size constraints) (#26401)

AGENTS.md

@@ -9,6 +9,7 @@
 ### General Principles
 
 - Keep things in one function unless composable or reusable
+- Do not extract single-use helpers preemptively. Inline the logic at the call site unless the helper is reused, hides a genuinely complex boundary, or has a clear independent name that improves the caller.
 - Avoid `try`/`catch` where possible
 - Avoid using the `any` type
 - Use Bun APIs when possible, like `Bun.file()`

bun.lock

@@ -412,6 +412,7 @@
         "@opentui/solid": "catalog:",
         "@parcel/watcher": "2.5.1",
         "@pierre/diffs": "catalog:",
+        "@silvia-odwyer/photon-node": "0.3.4",
         "@solid-primitives/event-bus": "1.1.2",
         "@solid-primitives/scheduled": "1.5.2",
         "@standard-schema/spec": "1.0.0",
@@ -677,6 +678,7 @@
     "solid-js@1.9.10": "patches/solid-js@1.9.10.patch",
     "@standard-community/standard-openapi@0.2.9": "patches/@standard-community%2Fstandard-openapi@0.2.9.patch",
     "@npmcli/agent@4.0.0": "patches/@npmcli%2Fagent@4.0.0.patch",
+    "@silvia-odwyer/photon-node@0.3.4": "patches/@silvia-odwyer%2Fphoton-node@0.3.4.patch",
   },
   "overrides": {
     "@types/bun": "catalog:",
@@ -2035,6 +2037,8 @@
 
     "@sigstore/verify": ["@sigstore/verify@3.1.0", "", { "dependencies": { "@sigstore/bundle": "^4.0.0", "@sigstore/core": "^3.1.0", "@sigstore/protobuf-specs": "^0.5.0" } }, "sha512-mNe0Iigql08YupSOGv197YdHpPPr+EzDZmfCgMc7RPNaZTw5aLN01nBl6CHJOh3BGtnMIj83EeN4butBchc8Ag=="],
 
+    "@silvia-odwyer/photon-node": ["@silvia-odwyer/photon-node@0.3.4", "", {}, "sha512-bnly4BKB3KDTFxrUIcgCLbaeVVS8lrAkri1pEzskpmxu9MdfGQTy8b8EgcD83ywD3RPMsIulY8xJH5Awa+t9fA=="],
+
     "@sindresorhus/is": ["@sindresorhus/is@4.6.0", "", {}, "sha512-t09vSN3MdfsyCHoFcTRCH/iUtG7OJ0CsjzB8cjAmKc/va/kIgeDI/TxsigdncE/4be734m0cvIYwNaV4i2XqAw=="],
 
     "@slack/bolt": ["@slack/bolt@3.22.0", "", { "dependencies": { "@slack/logger": "^4.0.0", "@slack/oauth": "^2.6.3", "@slack/socket-mode": "^1.3.6", "@slack/types": "^2.13.0", "@slack/web-api": "^6.13.0", "@types/express": "^4.16.1", "@types/promise.allsettled": "^1.0.3", "@types/tsscmp": "^1.0.0", "axios": "^1.7.4", "express": "^4.21.0", "path-to-regexp": "^8.1.0", "promise.allsettled": "^1.0.2", "raw-body": "^2.3.3", "tsscmp": "^1.0.6" } }, "sha512-iKDqGPEJDnrVwxSVlFW6OKTkijd7s4qLBeSufoBsTM0reTyfdp/5izIQVkxNfzjHi3o6qjdYbRXkYad5HBsBog=="],

package.json

@@ -133,6 +133,7 @@
   },
   "patchedDependencies": {
     "@npmcli/agent@4.0.0": "patches/@npmcli%2Fagent@4.0.0.patch",
+    "@silvia-odwyer/photon-node@0.3.4": "patches/@silvia-odwyer%2Fphoton-node@0.3.4.patch",
     "@standard-community/standard-openapi@0.2.9": "patches/@standard-community%2Fstandard-openapi@0.2.9.patch",
     "solid-js@1.9.10": "patches/solid-js@1.9.10.patch"
   }

packages/opencode/package.json

@@ -119,6 +119,7 @@
     "@opentui/solid": "catalog:",
     "@parcel/watcher": "2.5.1",
     "@pierre/diffs": "catalog:",
+    "@silvia-odwyer/photon-node": "0.3.4",
     "@solid-primitives/event-bus": "1.1.2",
     "@solid-primitives/scheduled": "1.5.2",
     "@standard-schema/spec": "1.0.0",

packages/opencode/src/audio.d.ts

@@ -2,3 +2,8 @@ declare module "*.wav" {
   const file: string
   export default file
 }
+
+declare module "*.wasm" {
+  const file: string
+  export default file
+}

packages/opencode/src/config/attachment.ts

@@ -0,0 +1,30 @@
+export * as ConfigAttachment from "./attachment"
+
+import { Schema } from "effect"
+import { zod } from "@opencode-ai/core/effect-zod"
+import { PositiveInt, withStatics } from "@opencode-ai/core/schema"
+
+export const Image = Schema.Struct({
+  auto_resize: Schema.optional(Schema.Boolean).annotate({
+    description: "Resize images before sending them to the model when they exceed configured limits (default: true)",
+  }),
+  max_width: Schema.optional(PositiveInt).annotate({
+    description: "Maximum image width before resizing or rejecting the attachment (default: 2000)",
+  }),
+  max_height: Schema.optional(PositiveInt).annotate({
+    description: "Maximum image height before resizing or rejecting the attachment (default: 2000)",
+  }),
+  max_base64_bytes: Schema.optional(PositiveInt).annotate({
+    description: "Maximum base64 payload bytes for an image attachment (default: 4718592)",
+  }),
+})
+  .annotate({ identifier: "ImageAttachmentConfig" })
+  .pipe(withStatics((s) => ({ zod: zod(s) })))
+export type Image = Schema.Schema.Type<typeof Image>
+
+export const Info = Schema.Struct({
+  image: Schema.optional(Image).annotate({ description: "Image attachment configuration" }),
+})
+  .annotate({ identifier: "AttachmentConfig" })
+  .pipe(withStatics((s) => ({ zod: zod(s) })))
+export type Info = Schema.Schema.Type<typeof Info>

packages/opencode/src/config/config.ts

@@ -25,6 +25,7 @@ import { containsPath } from "../project/instance-context"
 import { zod } from "@opencode-ai/core/effect-zod"
 import { NonNegativeInt, PositiveInt, withStatics, type DeepMutable } from "@opencode-ai/core/schema"
 import { ConfigAgent } from "./agent"
+import { ConfigAttachment } from "./attachment"
 import { ConfigCommand } from "./command"
 import { ConfigFormatter } from "./formatter"
 import { ConfigLayout } from "./layout"
@@ -241,6 +242,9 @@ export const Info = Schema.Struct({
   layout: Schema.optional(ConfigLayout.Layout).annotate({ description: "@deprecated Always uses stretch layout." }),
   permission: Schema.optional(ConfigPermission.Info),
   tools: Schema.optional(Schema.Record(Schema.String, Schema.Boolean)),
+  attachment: Schema.optional(ConfigAttachment.Info).annotate({
+    description: "Attachment processing configuration, including image size limits and resizing behavior",
+  }),
   enterprise: Schema.optional(
     Schema.Struct({
       url: Schema.optional(Schema.String).annotate({ description: "Enterprise URL" }),

packages/opencode/src/image/image.ts

@@ -0,0 +1,180 @@
+import { Config } from "@/config/config"
+import type { MessageV2 } from "@/session/message-v2"
+import * as Log from "@opencode-ai/core/util/log"
+import { Context, Effect, Layer, Schema } from "effect"
+
+const MAX_BASE64_BYTES = 4.5 * 1024 * 1024
+const MAX_WIDTH = 2000
+const MAX_HEIGHT = 2000
+const AUTO_RESIZE = true
+const JPEG_QUALITIES = [80, 85, 70, 55, 40]
+const log = Log.create({ service: "image" })
+
+export class PhotonUnavailableError extends Schema.TaggedErrorClass<PhotonUnavailableError>()(
+  "ImagePhotonUnavailableError",
+  {},
+) {
+  override get message() {
+    return "Photon image processor is unavailable"
+  }
+}
+
+export class InvalidDataUrlError extends Schema.TaggedErrorClass<InvalidDataUrlError>()("ImageInvalidDataUrlError", {
+  url: Schema.String,
+}) {
+  override get message() {
+    return "Image URL must be a base64 data URL"
+  }
+}
+
+export class DecodeError extends Schema.TaggedErrorClass<DecodeError>()("ImageDecodeError", {}) {
+  override get message() {
+    return "Image could not be decoded"
+  }
+}
+
+export class SizeError extends Schema.TaggedErrorClass<SizeError>()("ImageSizeError", {
+  bytes: Schema.Number,
+  max: Schema.Number,
+  width: Schema.Number,
+  height: Schema.Number,
+  max_width: Schema.Number,
+  max_height: Schema.Number,
+}) {
+  override get message() {
+    return `Image ${this.width}x${this.height} with base64 size ${this.bytes} exceeds configured limits and could not be resized below ${this.max_width}x${this.max_height}/${this.max} bytes`
+  }
+}
+
+export type Error = PhotonUnavailableError | InvalidDataUrlError | DecodeError | SizeError
+
+export interface Interface {
+  readonly normalize: (input: MessageV2.FilePart) => Effect.Effect<MessageV2.FilePart, Error>
+}
+
+export class Service extends Context.Service<Service, Interface>()("@opencode/Image") {}
+
+export const layer = Layer.effect(
+  Service,
+  Effect.gen(function* () {
+    const config = yield* Config.Service
+    const loadPhoton = yield* Effect.cached(
+      Effect.promise(async () => {
+        try {
+          const photonWasm = (await import("@silvia-odwyer/photon-node/photon_rs_bg.wasm", { with: { type: "file" } }))
+            .default
+          // Patched photon-node reads this during module init so Bun compiled binaries use the embedded wasm path.
+          ;(globalThis as typeof globalThis & { __OPENCODE_PHOTON_WASM_PATH?: string }).__OPENCODE_PHOTON_WASM_PATH =
+            photonWasm
+          return await import("@silvia-odwyer/photon-node")
+        } catch {
+          return null
+        }
+      }),
+    )
+
+    const normalize = Effect.fn("Image.normalize")(function* (input: MessageV2.FilePart) {
+      const image = (yield* config.get()).attachment?.image
+      const info = {
+        autoResize: image?.auto_resize ?? AUTO_RESIZE,
+        maxWidth: image?.max_width ?? MAX_WIDTH,
+        maxHeight: image?.max_height ?? MAX_HEIGHT,
+        maxBase64Bytes: image?.max_base64_bytes ?? MAX_BASE64_BYTES,
+      }
+      if (!input.url.startsWith("data:") || !input.url.includes(";base64,"))
+        return yield* new InvalidDataUrlError({ url: input.url })
+
+      const base64 = input.url.slice(input.url.indexOf(";base64,") + ";base64,".length)
+      const photon = yield* loadPhoton
+      if (!photon) return yield* new PhotonUnavailableError()
+
+      const decoded = yield* Effect.sync(() => {
+        try {
+          return photon.PhotonImage.new_from_byteslice(Buffer.from(base64, "base64"))
+        } catch {
+          return undefined
+        }
+      })
+      if (!decoded) return yield* new DecodeError()
+
+      try {
+        const originalWidth = decoded.get_width()
+        const originalHeight = decoded.get_height()
+        if (
+          originalWidth <= info.maxWidth &&
+          originalHeight <= info.maxHeight &&
+          Buffer.byteLength(base64, "utf8") <= info.maxBase64Bytes
+        )
+          return input
+        if (!info.autoResize)
+          return yield* new SizeError({
+            bytes: Buffer.byteLength(base64, "utf8"),
+            max: info.maxBase64Bytes,
+            width: originalWidth,
+            height: originalHeight,
+            max_width: info.maxWidth,
+            max_height: info.maxHeight,
+          })
+
+        const scale = Math.min(1, info.maxWidth / originalWidth, info.maxHeight / originalHeight)
+        for (const size of Array.from({ length: 32 }).reduce<Array<{ width: number; height: number }>>((acc) => {
+          const previous = acc.at(-1) ?? {
+            width: Math.max(1, Math.round(originalWidth * scale)),
+            height: Math.max(1, Math.round(originalHeight * scale)),
+          }
+          const next =
+            acc.length === 0
+              ? previous
+              : {
+                  width: previous.width === 1 ? 1 : Math.max(1, Math.floor(previous.width * 0.75)),
+                  height: previous.height === 1 ? 1 : Math.max(1, Math.floor(previous.height * 0.75)),
+                }
+          return acc.some((item) => item.width === next.width && item.height === next.height) ? acc : [...acc, next]
+        }, [])) {
+          const resized = photon.resize(decoded, size.width, size.height, photon.SamplingFilter.Lanczos3)
+          const candidate = [
+            { data: Buffer.from(resized.get_bytes()).toString("base64"), mime: "image/png" },
+            ...JPEG_QUALITIES.map((quality) => ({
+              data: Buffer.from(resized.get_bytes_jpeg(quality)).toString("base64"),
+              mime: "image/jpeg",
+            })),
+          ]
+            .map((item) => ({ ...item, bytes: Buffer.byteLength(item.data, "utf8") }))
+            .find((item) => item.bytes <= info.maxBase64Bytes)
+          resized.free()
+
+          if (candidate) {
+            log.info("using resized image", {
+              from_mime: input.mime,
+              to_mime: candidate.mime,
+              from: `${originalWidth}x${originalHeight}`,
+              to: `${size.width}x${size.height}`,
+            })
+            return {
+              ...input,
+              mime: candidate.mime,
+              url: `data:${candidate.mime};base64,${candidate.data}`,
+            }
+          }
+        }
+
+        return yield* new SizeError({
+          bytes: Buffer.byteLength(base64, "utf8"),
+          max: info.maxBase64Bytes,
+          width: originalWidth,
+          height: originalHeight,
+          max_width: info.maxWidth,
+          max_height: info.maxHeight,
+        })
+      } finally {
+        decoded.free()
+      }
+    })
+
+    return Service.of({ normalize })
+  }),
+)
+
+export const defaultLayer = layer.pipe(Layer.provide(Config.defaultLayer))
+
+export * as Image from "./image"

packages/opencode/src/server/routes/instance/httpapi/handlers/session.ts

@@ -203,13 +203,15 @@ export const sessionHandlers = HttpApiBuilder.group(InstanceHttpApi, "session",
       params: { sessionID: SessionID }
       payload: typeof InitPayload.Type
     }) {
-      yield* promptSvc.command({
-        sessionID: ctx.params.sessionID,
-        messageID: ctx.payload.messageID,
-        model: `${ctx.payload.providerID}/${ctx.payload.modelID}`,
-        command: Command.Default.INIT,
-        arguments: "",
-      })
+      yield* promptSvc
+        .command({
+          sessionID: ctx.params.sessionID,
+          messageID: ctx.payload.messageID,
+          model: `${ctx.payload.providerID}/${ctx.payload.modelID}`,
+          command: Command.Default.INIT,
+          arguments: "",
+        })
+        .pipe(Effect.mapError(() => new HttpApiError.BadRequest({})))
       return true
     })
 
@@ -258,18 +260,18 @@ export const sessionHandlers = HttpApiBuilder.group(InstanceHttpApi, "session",
     }) {
       const instance = yield* InstanceState.context
       const workspace = yield* InstanceState.workspaceID
+      const message = yield* promptSvc
+        .prompt({
+          ...ctx.payload,
+          sessionID: ctx.params.sessionID,
+        })
+        .pipe(
+          Effect.provideService(InstanceRef, instance),
+          Effect.provideService(WorkspaceRef, workspace),
+          Effect.mapError(() => new HttpApiError.BadRequest({})),
+        )
       return HttpServerResponse.stream(
-        Stream.fromEffect(
-          promptSvc
-            .prompt({
-              ...ctx.payload,
-              sessionID: ctx.params.sessionID,
-            })
-            .pipe(Effect.provideService(InstanceRef, instance), Effect.provideService(WorkspaceRef, workspace)),
-        ).pipe(
-          Stream.map((message) => JSON.stringify(message)),
-          Stream.encodeText,
-        ),
+        Stream.make(JSON.stringify(message)).pipe(Stream.encodeText),
         { contentType: "application/json" },
       )
     })
@@ -297,7 +299,9 @@ export const sessionHandlers = HttpApiBuilder.group(InstanceHttpApi, "session",
       params: { sessionID: SessionID }
       payload: typeof CommandPayload.Type
     }) {
-      return yield* promptSvc.command({ ...ctx.payload, sessionID: ctx.params.sessionID })
+      return yield* promptSvc
+        .command({ ...ctx.payload, sessionID: ctx.params.sessionID })
+        .pipe(Effect.mapError(() => new HttpApiError.BadRequest({})))
     })
 
     const shell = Effect.fn("SessionHttpApi.shell")(function* (ctx: {

packages/opencode/src/session/processor.ts

@@ -1,4 +1,4 @@
-import { Cause, Deferred, Effect, Layer, Context, Scope } from "effect"
+import { Cause, Deferred, Effect, Exit, Layer, Context, Scope } from "effect"
 import * as Stream from "effect/Stream"
 import { Agent } from "@/agent/agent"
 import { Bus } from "@/bus"
@@ -9,6 +9,7 @@ import { Snapshot } from "@/snapshot"
 import * as Session from "./session"
 import { LLM } from "./llm"
 import { MessageV2 } from "./message-v2"
+import { Image } from "@/image/image"
 import { isOverflow } from "./overflow"
 import { PartID } from "./schema"
 import type { SessionID } from "./schema"
@@ -92,6 +93,7 @@ export const layer: Layer.Layer<
   | LLM.Service
   | Permission.Service
   | Plugin.Service
+  | Image.Service
   | SessionSummary.Service
   | SessionStatus.Service
 > = Layer.effect(
@@ -108,6 +110,7 @@ export const layer: Layer.Layer<
     const summary = yield* SessionSummary.Service
     const scope = yield* Scope.Scope
     const status = yield* SessionStatus.Service
+    const image = yield* Image.Service
 
     const create = Effect.fn("SessionProcessor.create")(function* (input: Input) {
       // Pre-capture snapshot before the LLM stream starts. The AI SDK
@@ -377,17 +380,43 @@ export const layer: Layer.Layer<
 
           case "tool-result": {
             const toolCall = yield* readToolCall(value.toolCallId)
+            const toolAttachments: MessageV2.FilePart[] = (
+              Array.isArray(value.output.attachments) ? value.output.attachments : []
+            ).filter(
+              (attachment: unknown): attachment is MessageV2.FilePart =>
+                isRecord(attachment) &&
+                attachment.type === "file" &&
+                typeof attachment.mime === "string" &&
+                typeof attachment.url === "string",
+            )
+            const normalized = yield* Effect.forEach(
+              toolAttachments,
+              (attachment) =>
+                attachment.mime.startsWith("image/")
+                  ? image.normalize(attachment).pipe(Effect.exit)
+                  : Effect.succeed(Exit.succeed<MessageV2.FilePart>(attachment)),
+            )
+            const omitted = normalized.filter(Exit.isFailure).length
+            const attachments = normalized.filter(Exit.isSuccess).map((item) => item.value)
+            const output = {
+              ...value.output,
+              output:
+                omitted === 0
+                  ? value.output.output
+                  : `${value.output.output}\n\n[${omitted} image${omitted === 1 ? "" : "s"} omitted: could not be resized below the inline image size limit.]`,
+              attachments: attachments?.length ? attachments : undefined,
+            }
             // TODO(v2): Temporary dual-write while migrating session messages to v2 events.
             EventV2.run(SessionEvent.Tool.Success.Sync, {
               sessionID: ctx.sessionID,
               callID: value.toolCallId,
-              structured: value.output.metadata,
+              structured: output.metadata,
               content: [
                 {
                   type: "text",
-                  text: value.output.output,
+                  text: output.output,
                 },
-                ...(value.output.attachments?.map((item: MessageV2.FilePart) => ({
+                ...(output.attachments?.map((item: MessageV2.FilePart) => ({
                   type: "file",
                   uri: item.url,
                   mime: item.mime,
@@ -399,7 +428,7 @@ export const layer: Layer.Layer<
               },
               timestamp: DateTime.makeUnsafe(Date.now()),
             })
-            yield* completeToolCall(value.toolCallId, value.output)
+            yield* completeToolCall(value.toolCallId, output)
             return
           }
 
@@ -758,6 +787,7 @@ export const defaultLayer = Layer.suspend(() =>
     Layer.provide(Plugin.defaultLayer),
     Layer.provide(SessionSummary.defaultLayer),
     Layer.provide(SessionStatus.defaultLayer),
+    Layer.provide(Image.defaultLayer),
     Layer.provide(Bus.layer),
     Layer.provide(Config.defaultLayer),
   ),

packages/opencode/src/session/prompt.ts

@@ -43,6 +43,7 @@ import { Shell } from "@/shell/shell"
 import { ShellID } from "@/tool/shell/id"
 import { AppFileSystem } from "@opencode-ai/core/filesystem"
 import { Truncate } from "@/tool/truncate"
+import { Image } from "@/image/image"
 import { decodeDataUrl } from "@/util/data-url"
 import { Process } from "@/util/process"
 import { Cause, Effect, Exit, Latch, Layer, Option, Scope, Context, Schema, Types } from "effect"
@@ -80,10 +81,10 @@ const elog = EffectLogger.create({ service: "session.prompt" })
 
 export interface Interface {
   readonly cancel: (sessionID: SessionID) => Effect.Effect<void>
-  readonly prompt: (input: PromptInput) => Effect.Effect<MessageV2.WithParts>
+  readonly prompt: (input: PromptInput) => Effect.Effect<MessageV2.WithParts, Image.Error>
   readonly loop: (input: LoopInput) => Effect.Effect<MessageV2.WithParts>
   readonly shell: (input: ShellInput) => Effect.Effect<MessageV2.WithParts>
-  readonly command: (input: CommandInput) => Effect.Effect<MessageV2.WithParts>
+  readonly command: (input: CommandInput) => Effect.Effect<MessageV2.WithParts, Image.Error>
   readonly resolvePromptParts: (template: string) => Effect.Effect<PromptInput["parts"]>
 }
 
@@ -108,6 +109,7 @@ export const layer = Layer.effect(
     const lsp = yield* LSP.Service
     const registry = yield* ToolRegistry.Service
     const truncate = yield* Truncate.Service
+    const image = yield* Image.Service
     const spawner = yield* ChildProcessSpawner.ChildProcessSpawner
     const scope = yield* Scope.Scope
     const instruction = yield* Instruction.Service
@@ -123,7 +125,7 @@ export const layer = Layer.effect(
       return {
         cancel: (sessionID: SessionID) => cancel(sessionID),
         resolvePromptParts: (template: string) => resolvePromptParts(template),
-        prompt: (input: PromptInput) => prompt(input),
+        prompt: (input: PromptInput) => prompt(input).pipe(Effect.catch(Effect.die)),
       } satisfies TaskPromptOps
     })
 
@@ -1259,7 +1261,7 @@ NOTE: At any point in time through this workflow you should feel free to ask the
         return [{ ...part, messageID: info.id, sessionID: input.sessionID }]
       })
 
-      const parts = yield* Effect.forEach(input.parts, resolvePart, { concurrency: "unbounded" }).pipe(
+      const resolvedParts = yield* Effect.forEach(input.parts, resolvePart, { concurrency: "unbounded" }).pipe(
         Effect.map((x) => x.flat().map(assign)),
       )
 
@@ -1272,7 +1274,13 @@ NOTE: At any point in time through this workflow you should feel free to ask the
           messageID: input.messageID,
           variant: input.variant,
         },
-        { message: info, parts },
+        { message: info, parts: resolvedParts },
+      )
+
+      const parts = yield* Effect.forEach(resolvedParts, (part) =>
+        part.type === "file" && part.mime.startsWith("image/")
+          ? image.normalize(part)
+          : Effect.succeed(part),
       )
 
       const parsed = MessageV2.Info.zod.safeParse(info)
@@ -1368,7 +1376,7 @@ NOTE: At any point in time through this workflow you should feel free to ask the
       return { info, parts }
     }, Effect.scoped)
 
-    const prompt: (input: PromptInput) => Effect.Effect<MessageV2.WithParts> = Effect.fn("SessionPrompt.prompt")(
+    const prompt: (input: PromptInput) => Effect.Effect<MessageV2.WithParts, Image.Error> = Effect.fn("SessionPrompt.prompt")(
       function* (input: PromptInput) {
         const session = yield* sessions.get(input.sessionID).pipe(Effect.orDie)
         yield* revert.cleanup(session)
@@ -1788,6 +1796,7 @@ export const defaultLayer = Layer.suspend(() =>
     Layer.provide(Session.defaultLayer),
     Layer.provide(SessionRevert.defaultLayer),
     Layer.provide(SessionSummary.defaultLayer),
+    Layer.provide(Image.defaultLayer),
     Layer.provide(
       Layer.mergeAll(
         Agent.defaultLayer,

packages/opencode/test/image/image.test.ts

@@ -0,0 +1,78 @@
+import { describe, expect } from "bun:test"
+import { Cause, Effect, Exit, Layer } from "effect"
+import { Image } from "@/image/image"
+import { MessageID, PartID, SessionID } from "@/session/schema"
+import { TestConfig } from "../fixture/config"
+import { testEffect } from "../lib/effect"
+
+const it = testEffect(Layer.mergeAll(Image.layer.pipe(Layer.provide(TestConfig.layer()))))
+const tiny = testEffect(
+  Layer.mergeAll(
+    Image.layer.pipe(
+      Layer.provide(TestConfig.layer({ get: () => Effect.succeed({ attachment: { image: { max_base64_bytes: 1 } } }) })),
+    ),
+  ),
+)
+
+function part(mime: string, data: string) {
+  return {
+    id: PartID.ascending(),
+    messageID: MessageID.ascending(),
+    sessionID: SessionID.make("ses_test"),
+    type: "file" as const,
+    mime,
+    url: `data:${mime};base64,${data}`,
+  }
+}
+
+describe("Image", () => {
+  it.effect("normalizes generated png and jpeg attachments", () =>
+    Effect.gen(function* () {
+      const photon = yield* Effect.promise(() => import("@silvia-odwyer/photon-node"))
+      const source = new photon.PhotonImage(
+        new Uint8Array(Array.from({ length: 64 * 64 * 4 }, (_, index) => (index % 4 === 3 ? 255 : index % 251))),
+        64,
+        64,
+      )
+      const image = yield* Image.Service
+      const results = yield* Effect.all([
+        image.normalize(part("image/png", Buffer.from(source.get_bytes()).toString("base64"))),
+        image.normalize(part("image/jpeg", Buffer.from(source.get_bytes_jpeg(90)).toString("base64"))),
+      ])
+
+      source.free()
+      expect(results.map((result) => result.url.startsWith(`data:${result.mime};base64,`))).toEqual([true, true])
+      expect(results.every((result) => result.mime === "image/png" || result.mime === "image/jpeg")).toBe(true)
+    }),
+  )
+
+  it.effect("accepts webp attachments that are already within limits", () =>
+    Effect.gen(function* () {
+      const image = yield* Image.Service
+      const input = part("image/webp", "UklGRiIAAABXRUJQVlA4IBYAAAAwAQCdASoBAAEADsD+JaQAA3AAAAAA")
+
+      expect(yield* image.normalize(input)).toEqual(input)
+    }),
+  )
+
+  tiny.effect("fails with a typed size error when no resized candidate fits", () =>
+    Effect.gen(function* () {
+      const photon = yield* Effect.promise(() => import("@silvia-odwyer/photon-node"))
+      const source = new photon.PhotonImage(new Uint8Array(Array.from({ length: 4 }, () => 255)), 1, 1)
+      const image = yield* Image.Service
+      const exit = yield* image.normalize(part("image/png", Buffer.from(source.get_bytes()).toString("base64"))).pipe(Effect.exit)
+
+      source.free()
+      expect(Exit.isFailure(exit)).toBe(true)
+      if (Exit.isFailure(exit)) {
+        const error = Cause.squash(exit.cause)
+        expect(error).toBeInstanceOf(Image.SizeError)
+        if (error instanceof Image.SizeError) {
+          expect(error.width).toBe(1)
+          expect(error.height).toBe(1)
+          expect(error.max).toBe(1)
+        }
+      }
+    }),
+  )
+})

packages/opencode/test/session/compaction.test.ts

@@ -5,6 +5,7 @@ import * as Stream from "effect/Stream"
 import z from "zod"
 import { Bus } from "../../src/bus"
 import { Config } from "@/config/config"
+import { Image } from "@/image/image"
 import { Agent } from "../../src/agent/agent"
 import { LLM } from "../../src/session/llm"
 import { SessionCompaction } from "../../src/session/compaction"
@@ -278,7 +279,7 @@ function llm() {
 function liveRuntime(layer: Layer.Layer<LLM.Service>, provider = ProviderTest.fake(), config = Config.defaultLayer) {
   const bus = Bus.layer
   const status = SessionStatus.layer.pipe(Layer.provide(bus))
-  const processor = SessionProcessorModule.SessionProcessor.layer.pipe(Layer.provide(summary))
+  const processor = SessionProcessorModule.SessionProcessor.layer.pipe(Layer.provide(summary), Layer.provide(Image.defaultLayer))
   return ManagedRuntime.make(
     Layer.mergeAll(SessionCompaction.layer.pipe(Layer.provide(processor)), processor, bus, status).pipe(
       Layer.provide(provider.layer),

packages/opencode/test/session/processor-effect.test.ts

@@ -6,6 +6,7 @@ import type { Agent } from "../../src/agent/agent"
 import { Agent as AgentSvc } from "../../src/agent/agent"
 import { Bus } from "../../src/bus"
 import { Config } from "@/config/config"
+import { Image } from "@/image/image"
 import { Permission } from "../../src/permission"
 import { Plugin } from "../../src/plugin"
 import { Provider } from "@/provider/provider"
@@ -168,7 +169,7 @@ const deps = Layer.mergeAll(
 ).pipe(Layer.provideMerge(infra))
 const env = Layer.mergeAll(
   TestLLMServer.layer,
-  SessionProcessor.layer.pipe(Layer.provide(summary), Layer.provideMerge(deps)),
+  SessionProcessor.layer.pipe(Layer.provide(summary), Layer.provide(Image.defaultLayer), Layer.provideMerge(deps)),
 )
 
 const it = testEffect(env)

packages/opencode/test/session/prompt.test.ts

@@ -16,6 +16,7 @@ import { Plugin } from "../../src/plugin"
 import { Provider as ProviderSvc } from "@/provider/provider"
 import { Env } from "../../src/env"
 import { Git } from "../../src/git"
+import { Image } from "../../src/image/image"
 import { ModelID, ProviderID } from "../../src/provider/schema"
 import { Question } from "../../src/question"
 import { Todo } from "../../src/session/todo"
@@ -187,12 +188,13 @@ function makeHttp() {
     Layer.provideMerge(deps),
   )
   const trunc = Truncate.layer.pipe(Layer.provideMerge(deps))
-  const proc = SessionProcessor.layer.pipe(Layer.provide(summary), Layer.provideMerge(deps))
+  const proc = SessionProcessor.layer.pipe(Layer.provide(summary), Layer.provide(Image.defaultLayer), Layer.provideMerge(deps))
   const compact = SessionCompaction.layer.pipe(Layer.provideMerge(proc), Layer.provideMerge(deps))
   return Layer.mergeAll(
     TestLLMServer.layer,
     SessionPrompt.layer.pipe(
       Layer.provide(SessionRevert.defaultLayer),
+      Layer.provide(Image.defaultLayer),
       Layer.provide(summary),
       Layer.provideMerge(run),
       Layer.provideMerge(compact),

packages/opencode/test/session/snapshot-tool-race.test.ts

@@ -41,6 +41,7 @@ import { Plugin } from "../../src/plugin"
 import { Provider as ProviderSvc } from "@/provider/provider"
 import { Env } from "../../src/env"
 import { Question } from "../../src/question"
+import { Image } from "../../src/image/image"
 import { Skill } from "../../src/skill"
 import { SystemPrompt } from "../../src/session/system"
 import { Todo } from "../../src/session/todo"
@@ -137,13 +138,18 @@ function makeHttp() {
     Layer.provideMerge(deps),
   )
   const trunc = Truncate.layer.pipe(Layer.provideMerge(deps))
-  const proc = SessionProcessor.layer.pipe(Layer.provide(SessionSummary.defaultLayer), Layer.provideMerge(deps))
+  const proc = SessionProcessor.layer.pipe(
+    Layer.provide(SessionSummary.defaultLayer),
+    Layer.provide(Image.defaultLayer),
+    Layer.provideMerge(deps),
+  )
   const compact = SessionCompaction.layer.pipe(Layer.provideMerge(proc), Layer.provideMerge(deps))
   return Layer.mergeAll(
     TestLLMServer.layer,
     SessionSummary.defaultLayer,
     SessionPrompt.layer.pipe(
       Layer.provide(SessionRevert.defaultLayer),
+      Layer.provide(Image.defaultLayer),
       Layer.provide(SessionSummary.defaultLayer),
       Layer.provideMerge(run),
       Layer.provideMerge(compact),

packages/sdk/js/src/v2/gen/types.gen.ts

@@ -1132,6 +1132,17 @@ export type McpRemoteConfig = {
  */
 export type LayoutConfig = "auto" | "stretch"
 
+export type ImageAttachmentConfig = {
+  auto_resize?: boolean
+  max_width?: number
+  max_height?: number
+  max_base64_bytes?: number
+}
+
+export type AttachmentConfig = {
+  image?: ImageAttachmentConfig
+}
+
 export type Config = {
   $schema?: string
   shell?: string
@@ -1246,6 +1257,7 @@ export type Config = {
   tools?: {
     [key: string]: boolean
   }
+  attachment?: AttachmentConfig
   enterprise?: {
     url?: string
   }

patches/@silvia-odwyer%2Fphoton-node@0.3.4.patch

@@ -0,0 +1,14 @@
+diff --git a/photon_rs.js b/photon_rs.js
+index 8f4144d..b83e9a9 100644
+--- a/photon_rs.js
++++ b/photon_rs.js
+@@ -4509,7 +4509,8 @@ module.exports.__wbindgen_init_externref_table = function() {
+     ;
+ };
+ 
+-const path = require('path').join(__dirname, 'photon_rs_bg.wasm');
++// Allow opencode's Bun compiled binary to point photon-node at its embedded wasm asset.
++const path = globalThis.__OPENCODE_PHOTON_WASM_PATH || require('path').join(__dirname, 'photon_rs_bg.wasm');
+ const bytes = require('fs').readFileSync(path);
+ 
+ const wasmModule = new WebAssembly.Module(bytes);