fix(opencode): graceful error handling for PDF/image file read failures

packages/opencode/src/provider/transform.ts

@@ -392,6 +392,21 @@ function unsupportedParts(msgs: ModelMessage[], model: Provider.Model): ModelMes
         }
       }
 
+      // Check for empty base64 PDF data
+      if (part.type === "file" && part.mediaType === "application/pdf") {
+        const url = "url" in part ? String(part.url) : ""
+        if (url.startsWith("data:")) {
+          const match = url.match(/^data:([^;]+);base64,(.*)$/)
+          if (match && (!match[2] || match[2].length === 0)) {
+            const name = part.filename ? `"${part.filename}"` : "PDF"
+            return {
+              type: "text" as const,
+              text: `ERROR: ${name} file is empty or corrupted. Please provide a valid PDF file.`,
+            }
+          }
+        }
+      }
+
       const mime = part.type === "image" ? String(part.image).split(";")[0].replace("data:", "") : part.mediaType
       const filename = part.type === "file" ? part.filename : undefined
       const modality = mimeToModality(mime)

packages/opencode/src/session/prompt.ts

@@ -973,6 +973,25 @@ export const layer = Layer.effect(
                 ]
               }
 
+              const readExit = yield* fsys.readFile(filepath).pipe(Effect.exit)
+              if (Exit.isFailure(readExit)) {
+                const error = Cause.squash(readExit.cause)
+                log.error("failed to read file attachment", { error, filepath })
+                const message = error instanceof Error ? error.message : String(error)
+                yield* events.publish(Session.Event.Error, {
+                  sessionID: input.sessionID,
+                  error: new NamedError.Unknown({ message }).toObject(),
+                })
+                return [
+                  {
+                    messageID: info.id,
+                    sessionID: input.sessionID,
+                    type: "text",
+                    synthetic: true,
+                    text: `Failed to read file ${filepath}: ${message}`,
+                  },
+                ]
+              }
               return [
                 {
                   messageID: info.id,
@@ -986,9 +1005,7 @@ export const layer = Layer.effect(
                   messageID: info.id,
                   sessionID: input.sessionID,
                   type: "file",
-                  url:
-                    `data:${mime};base64,` +
-                    Buffer.from(yield* fsys.readFile(filepath).pipe(Effect.catch(Effect.die))).toString("base64"),
+                  url: `data:${mime};base64,${Buffer.from(readExit.value).toString("base64")}`,
                   mime,
                   filename: part.filename!,
                   source: part.source,

packages/opencode/src/tool/read.ts

@@ -310,8 +310,17 @@ export const ReadTool = Tool.define<
       const isImage = SUPPORTED_IMAGE_MIMES.has(mime)
 
       if (isImage || isPdfAttachment(mime)) {
-        const bytes = yield* fs.readFile(filepath)
-        const msg = isPdfAttachment(mime) ? "PDF read successfully" : "Image read successfully"
+        const kind = isPdfAttachment(mime) ? "PDF" : "image"
+        const bytes = yield* fs.readFile(filepath).pipe(
+          Effect.catch((error) =>
+            Effect.fail(
+              new Error(
+                `Cannot read ${kind} file: ${filepath} (${error instanceof Error ? error.message : String(error)})`,
+              ),
+            ),
+          ),
+        )
+        const msg = `${kind === "PDF" ? "PDF" : "Image"} read successfully`
         return {
           title,
           output: msg,