codemode: Uint8Array constructor rejects valid fractional and NaN lengths #57633

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1. opencode-agent commented on Oct 21, 2026

   

   opencode-agentBot

   on Oct 21, 2026 – with OpenCode Agent

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   Thanks for the clear report. I reproduced this on the latest dev (c9b5a9f, @opencode/codemode 2.1.2).

   In Code Mode, new Uint8Array(1.9), new Uint8Array(-0.9), new Uint8Array(NaN) and new Uint8Array("2.9") all fail with RangeError: Invalid typed array length: …. Native JavaScript returns [0], [], [] and [0, 0]. Negative integers and ±Infinity correctly throw in both. The script below runs each case through CodeMode.execute and compares it with native JS.

   As you said, constructBytes in packages/codemode/src/stdlib/bytes.ts rejects lengths that aren't integers instead of truncating them first.

   Reproduction script (repro.ts)

   // Run from packages/codemode of an opencode dev checkout: bun /workspace/repro/repro.ts
   // (or set CODEMODE_DIR to the packages/codemode directory)
   const dir = process.env.CODEMODE_DIR ?? process.cwd()
   const { Effect } = await import(Bun.resolveSync("effect", dir))
   const { CodeMode } = await import(`${dir}/src/index.js`)
   
   const cases: Array<[string, string]> = [
     ["1.9", "[0]"], ["-0.9", "[]"], ["NaN", "[]"], ['"2.9"', "[0,0]"],
     ["-1", "RangeError"], ["Infinity", "RangeError"], ["-Infinity", "RangeError"],
   ]
   for (const [input, expected] of cases) {
     const native = (() => { try { return JSON.stringify([...new Uint8Array(eval(input))]) } catch (e) { return String((e as Error).name) } })()
     const result = await Effect.runPromise(
       CodeMode.execute({ code: `return [...new Uint8Array(${input})]`, tools: {} }),
     ).catch((e) => ({ thrown: String(e) }))
     console.log(`new Uint8Array(${input})  expected=${expected} native=${native}  codemode=${JSON.stringify(result)}`)
   }

   Run it: bun repro.ts
2. opencode-agent

   added

   reproduced

   on Oct 21, 2026
3. sdivyanshu90 commented on Oct 21, 2026

   

   sdivyanshu90

   on Oct 21, 2026

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   Hi @rekram1-node, I'd like to claim this issue. I've prepared a fix with regression tests: constructor lengths are normalized before validation, so fractions truncate and NaN becomes zero. Negative integer lengths, infinities, and oversized allocations still fail. The full CodeMode suite and package typecheck pass.

   Could you please review the proposed fix when you have some time? I can raise a PR, but GitHub currently blocks creation with: "You've reached this repository's open pull request limit." I'll open it once a slot is available. Thanks!
4. rekram1-node commented on Oct 21, 2026

   

   rekram1-node

   on Oct 21, 2026

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   #57632 (comment)
5. rekram1-node

   closed this as not plannedon Oct 21, 2026