feat(hooks): add read-image-resizer hook

Intercepts Read tool output with image attachments and resizes to comply with Anthropic API limits (≤1568px long edge, ≤5MB). Only activates for Anthropic provider sessions and appends resize metadata (original/new resolution, token count) to tool output. Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode) Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>
2026-02-28 13:16:43 +09:00
parent 74f7992442
commit cc6ab1addc
12 changed files with 1121 additions and 0 deletions
@@ -0,0 +1,187 @@
+import type { ImageDimensions } from "./types"
+
+import { extractBase64Data } from "../../tools/look-at/mime-type-inference"
+
+function toImageDimensions(width: number, height: number): ImageDimensions | null {
+  if (!Number.isFinite(width) || !Number.isFinite(height)) {
+    return null
+  }
+
+  if (width <= 0 || height <= 0) {
+    return null
+  }
+
+  return { width, height }
+}
+
+function parsePngDimensions(buffer: Buffer): ImageDimensions | null {
+  if (buffer.length < 24) {
+    return null
+  }
+
+  const isPngSignature =
+    buffer[0] === 0x89 &&
+    buffer[1] === 0x50 &&
+    buffer[2] === 0x4e &&
+    buffer[3] === 0x47 &&
+    buffer[4] === 0x0d &&
+    buffer[5] === 0x0a &&
+    buffer[6] === 0x1a &&
+    buffer[7] === 0x0a
+
+  if (!isPngSignature || buffer.toString("ascii", 12, 16) !== "IHDR") {
+    return null
+  }
+
+  const width = buffer.readUInt32BE(16)
+  const height = buffer.readUInt32BE(20)
+  return toImageDimensions(width, height)
+}
+
+function parseGifDimensions(buffer: Buffer): ImageDimensions | null {
+  if (buffer.length < 10) {
+    return null
+  }
+
+  if (buffer.toString("ascii", 0, 4) !== "GIF8") {
+    return null
+  }
+
+  const width = buffer.readUInt16LE(6)
+  const height = buffer.readUInt16LE(8)
+  return toImageDimensions(width, height)
+}
+
+function parseJpegDimensions(buffer: Buffer): ImageDimensions | null {
+  if (buffer.length < 4 || buffer[0] !== 0xff || buffer[1] !== 0xd8) {
+    return null
+  }
+
+  let offset = 2
+
+  while (offset < buffer.length) {
+    if (buffer[offset] !== 0xff) {
+      offset += 1
+      continue
+    }
+
+    while (offset < buffer.length && buffer[offset] === 0xff) {
+      offset += 1
+    }
+
+    if (offset >= buffer.length) {
+      return null
+    }
+
+    const marker = buffer[offset]
+    offset += 1
+
+    if (marker === 0xd9 || marker === 0xda) {
+      break
+    }
+
+    if (offset + 1 >= buffer.length) {
+      return null
+    }
+
+    const segmentLength = buffer.readUInt16BE(offset)
+    if (segmentLength < 2) {
+      return null
+    }
+
+    if ((marker === 0xc0 || marker === 0xc2) && offset + 7 < buffer.length) {
+      const height = buffer.readUInt16BE(offset + 3)
+      const width = buffer.readUInt16BE(offset + 5)
+      return toImageDimensions(width, height)
+    }
+
+    offset += segmentLength
+  }
+
+  return null
+}
+
+function readUInt24LE(buffer: Buffer, offset: number): number {
+  return buffer[offset] | (buffer[offset + 1] << 8) | (buffer[offset + 2] << 16)
+}
+
+function parseWebpDimensions(buffer: Buffer): ImageDimensions | null {
+  if (buffer.length < 16) {
+    return null
+  }
+
+  if (buffer.toString("ascii", 0, 4) !== "RIFF" || buffer.toString("ascii", 8, 12) !== "WEBP") {
+    return null
+  }
+
+  const chunkType = buffer.toString("ascii", 12, 16)
+
+  if (chunkType === "VP8 ") {
+    if (buffer[23] !== 0x9d || buffer[24] !== 0x01 || buffer[25] !== 0x2a) {
+      return null
+    }
+
+    const width = buffer.readUInt16LE(26) & 0x3fff
+    const height = buffer.readUInt16LE(28) & 0x3fff
+    return toImageDimensions(width, height)
+  }
+
+  if (chunkType === "VP8L") {
+    if (buffer.length < 25 || buffer[20] !== 0x2f) {
+      return null
+    }
+
+    const bits = buffer.readUInt32LE(21)
+    const width = (bits & 0x3fff) + 1
+    const height = ((bits >>> 14) & 0x3fff) + 1
+    return toImageDimensions(width, height)
+  }
+
+  if (chunkType === "VP8X") {
+    const width = readUInt24LE(buffer, 24) + 1
+    const height = readUInt24LE(buffer, 27) + 1
+    return toImageDimensions(width, height)
+  }
+
+  return null
+}
+
+export function parseImageDimensions(base64DataUrl: string, mimeType: string): ImageDimensions | null {
+  try {
+    if (!base64DataUrl || !mimeType) {
+      return null
+    }
+
+    const rawBase64 = extractBase64Data(base64DataUrl)
+    if (!rawBase64) {
+      return null
+    }
+
+    const buffer = Buffer.from(rawBase64, "base64")
+    if (buffer.length === 0) {
+      return null
+    }
+
+    const normalizedMime = mimeType.toLowerCase()
+
+    if (normalizedMime === "image/png") {
+      return parsePngDimensions(buffer)
+    }
+
+    if (normalizedMime === "image/gif") {
+      return parseGifDimensions(buffer)
+    }
+
+    if (normalizedMime === "image/jpeg" || normalizedMime === "image/jpg") {
+      return parseJpegDimensions(buffer)
+    }
+
+    if (normalizedMime === "image/webp") {
+      return parseWebpDimensions(buffer)
+    }
+
+    return null
+  } catch {
+    return null
+  }
+}