chat: pasting external PDF path triggers HTTP 500 instead of graceful fallback for models without PDF support #55387

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1. opencode-agent commented on Oct 14, 2026

   

   opencode-agentBot

   on Oct 14, 2026 – with OpenCode Agent

   Contributor

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   Thanks for the detailed report. I reproduced this on 2.0.28 and it still happens on the latest dev (34d8ded). It turns out to depend on the file size rather than on the file being outside the workspace or the model lacking PDF support.

   What I ran: in the TUI with a simulated model, I pasted the absolute path of a PDF from a folder outside the project, so the PDF 1 chip appeared, then sent a message.

   • With a tiny PDF (193 bytes), the message went through and the model replied.
   • With a ~7 MB PDF, sending failed with Failed to set up session / UnexpectedStatus: 500 and the prompt never reached the model.

   The server validates each attachment's base64 data with a regular expression that wrongly rejects valid data once the attachment is larger than about 6 MB. The request then fails with a 500 before the model is involved. That's why paths that aren't turned into an attachment, like your workaround, still work.

   This looks like the same root cause as #45558 (which has a proposed fix in #51272), and #54323 was already closed as a duplicate of it. If your PDF is smaller than ~6 MB, please say so here, because that would point to a separate problem.

   The recording and script below show both cases.

   recording.mp4

   

   

   Reproduction script (drive.ts)

   // Repro for anomalyco/opencode#55387: pasting the path of a PDF outside the
   // workspace into the TUI composer attaches it; sending fails with HTTP 500.
   // Creates /tmp/outside/small.pdf (193 B) and /tmp/outside/big.pdf (~7 MB) first.
   import { Effect, Stream } from "effect"
   import { mkdirSync, writeFileSync } from "node:fs"
   import { randomBytes } from "node:crypto"
   import { Llm, OpenCodeDriver } from "opencode-drive"
   
   const which = process.env.PDF ?? "big"
   const pdf = Buffer.from(
     "%PDF-1.4\n1 0 obj<</Type/Catalog/Pages 2 0 R>>endobj\n2 0 obj<</Type/Pages/Kids[3 0 R]/Count 1>>endobj\n3 0 obj<</Type/Page/Parent 2 0 R/MediaBox[0 0 200 200]>>endobj\ntrailer<</Root 1 0 R>>\n%%EOF\n",
   )
   mkdirSync("/tmp/outside", { recursive: true })
   writeFileSync("/tmp/outside/small.pdf", pdf)
   writeFileSync("/tmp/outside/big.pdf", Buffer.concat([pdf, randomBytes(7 * 1024 * 1024)]))
   const path = `/tmp/outside/${which}.pdf`
   
   export default OpenCodeDriver.use(
     {
       ...(process.env.OC_DEV ? { opencode: { dev: process.env.OC_DEV } } : {}),
       project: { git: true, files: { "README.md": "hello\n" } },
       tui: { recording: true, keypressOverlay: true },
     },
     ({ ui, llm }) =>
       Effect.gen(function* () {
         yield* llm.serve(() => Stream.make(Llm.text("I received your message.")))
         yield* Effect.sleep(1500)
         // Bracketed paste of the absolute path, as a terminal paste would deliver it
         yield* ui.type(`\x1b[200~${path}\x1b[201~`)
         yield* Effect.sleep(1500)
         yield* ui.screenshot(`${which}-pasted`)
         yield* ui.type(" summarize this pdf")
         yield* ui.enter()
         yield* Effect.sleep(5000)
         yield* ui.screenshot(`${which}-after-send`)
       }),
   )

   Run it with opencode-drive: opencode-drive run ./drive.ts. It drives opencode from your PATH; set OC_DEV to the path of an OpenCode checkout to run that from source instead.
2. opencode-agent

   added

   reproduced

   on Oct 14, 2026
3. IceofTea commented on Oct 14, 2026

   

   IceofTea

   on Oct 14, 2026

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   Thanks for the detailed triage! My PDF was 15.3 MB (16,086,359 bytes) — well above the ~6 MB threshold, so this matches the #45558 root cause and is not a separate sub-6MB issue. Feel free to close as a duplicate of #45558 if appropriate.
4. Tarquinen commented on Oct 20, 2026

   

   Tarquinen

   on Oct 20, 2026

   Member

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   Thanks for the report! As you mentioned, this is a duplicate of #45558, so I'm closing it. Please follow that issue for updates.

   — from 𝕺𝖕𝖊𝖓𝕮𝖔𝖉𝖊
5. Tarquinen

   closed this as a duplicateof attachments: dragging file or pasting file path into input fails session setup (Prompt.Base64 500 on /prompt) #45558 on Oct 20, 2026