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opencode api truncates large output when stdout is a pipe (un-awaited write before process.exit) #57816
Closed as duplicate
Description
Version: opencode v2.0.32 (source read at that tag); the same write is still on the default branch
(packages/cli/src/commands/handlers/api.ts:46, fetched 2026-10-21).
Reproduce
for i in $(seq 10); do opencode api GET /openapi.json | wc -c; done # 280292 bytes expected
opencode api GET /openapi.json > out.json; wc -c out.json # always 280292
Piped, the count stops at exactly 262144 with exit status 0 in 1 of 8 and 4 of 10 runs (Linux, v2.0.32).
Redirected to a file it is complete every time. The silent exit 0 is what makes it hard to notice.
Cause (v2.0.32)
packages/cli/src/commands/handlers/api.ts:45-46: the handler readsresponse.text()and calls
process.stdout.write(output + ...)once, with no callback and no drain.packages/cli/src/index.ts:139:Effect.tap(() => Effect.sync(() => process.exit(process.exitCode ?? 0)))
runs right after the handler.- Under Bun a write to a pipe larger than the pipe buffer is asynchronous, so
process.exitdiscards what
the reader has not drained. A write to a file is synchronous, hence complete. 262144 is the pipe buffer
size, not a number in the source.
Suggested fix: wait for the write before exiting, e.g.
yield* Effect.promise(() => new Promise<void>((done) => process.stdout.write(out, () => done())))
in the handler, or have the exit tap wait for stdout to drain.
Workaround we use: redirect stdout to a file, never a pipe.
Activity
opencode-agent commentedon Oct 21, 2026
Thanks for the precise write-up, including where in the code it happens. I think this is a duplicate of #52925, which reports the same problem: piped
opencode api getoutput is cut off at 4096-byte multiples (including 262144) with exit status 0, while redirecting to a file gives the complete output. The cause is the same too: the write isn't awaited beforeprocess.exit.Possible duplicates and related issues, ordered by likelihood:
opencode apitruncation when stdout is a pipe. Open PR fix(cli): flush api output before exit #52955 makes the handler wait for the stdout write before exiting, which is the fix you suggest.session export(PR fix(cli): flush session exports before exit #57347).Until that is merged, redirecting to a file (as you already do) is the workaround. The bot will close this issue as a duplicate in 1 day unless you reply explaining how your problem is different.
opencode-agent commentedon Oct 22, 2026
Closing this as a duplicate of #52925, as mentioned yesterday. That issue covers the same
opencode apitruncation when stdout is a pipe: output stops at 4096-byte multiples such as 262144, the exit status is still 0, and redirecting to a file gives the full output. Open PR #52955 makes the handler wait for the stdout write before the CLI exits. Until that lands, redirecting to a file is the workaround. Please follow #52925 for updates. If your problem turns out to be different, reply here and we can reopen.