import fails on UTF-16 files with BOM (Windows PowerShell redirection) #54306

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1. github-actions

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   neriousy

   on Oct 10, 2026
2. opencode-agent commented on Oct 10, 2026

   

   opencode-agentbot

   on Oct 10, 2026 – with OpenCode Agent

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   Thanks for the detailed report and for tracking down the cause!

   This was reproduced on the dev branch, which is OpenCode v1 (0.x/1.x). v1 now only gets fixes for critical bugs such as data loss, security problems or breakage with no workaround. This one has a straightforward workaround, so it's unlikely to be fixed in v1:

   opencode export <session-id> | Out-File -Encoding utf8 session.json
   # or convert an existing file:
   Get-Content session.json | Set-Content -Encoding utf8 session-utf8.json

   We'd encourage moving to v2 (npm package @opencode/cli), where the equivalent command is opencode session import <file>. From reading the v2 code, it also decodes local files as UTF-8, so the same PowerShell 5.1 round-trip may well fail there too. If you can confirm it happens on v2, or if you think this is critical for v1, please reply here and we'll take another look.

   Related:

   • fix(core): decode UTF-16 BOMs in readJson #54307: your PR adding UTF-16 BOM decoding to v1's readJson
   • opencode export can write session JSON that opencode import cannot read in 1.4.3 #21941: an earlier, different export/import failure (legacy session data shapes in 1.4.3)
   • edit and apply_patch silently corrupt non-UTF-8 files (U+FFFD replacement) #45924, Encoding issue: non-UTF-8 encoded files on Windows [I find a solution] #30187: broader problems with files that aren't UTF-8
3. opencode-agent

   added

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   triaging

   on Oct 10, 2026
4. reynold-hu commented on Oct 10, 2026

   

   reynold-hu

   on Oct 10, 2026

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   Confirmed on v2 — this does not reproduce there.

   Tested @opencode/cli@2.0.26 on Windows 10 with PowerShell 5.1, importing the same session export twice:

   • UTF-16LE with BOM (from opencode export <id> > session.json): SchemaError: Missing key ["info"]["location"]
   • UTF-8 without BOM: SchemaError: Missing key ["info"]["location"]

   Both inputs reach schema validation with the identical error (the known v1-export/v2-schema difference, #49314), so v2 parses the UTF-16 file correctly.

   Why: v2's session import reads the file with Bun.file(input.file).text() (packages/cli/src/commands/handlers/session/import.ts), and Bun.file().text() decodes a UTF-16 BOM. FSUtil.readJson (packages/util/src/fs-util.ts) is not in that code path, so it never sees this file.

   So this is v1-only, and v1 has the workaround you posted. Closing as not planned — thanks for the triage.
5. reynold-hu

   closed this as not plannedon Oct 10, 2026
6. opencode-agent commented on Oct 10, 2026

   

   opencode-agentbot

   on Oct 10, 2026 – with OpenCode Agent

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   Thanks for testing on v2 and for the correction. You're right: Bun.file().text() decodes the UTF-16 BOM, so v2's opencode session import reads the file fine. I was wrong to say v2 might have the same problem. Since v2 gives the same error for the UTF-16LE and UTF-8 files, this only affects v1, and v1 has the Out-File -Encoding utf8 workaround.

   The Missing key ["info"]["location"] error you got when importing a v1 export into v2 is a separate problem, tracked in #49314.

   This issue will be closed as not planned. Thanks again for the thorough report.
7. opencode-agent commented on Oct 11, 2026

   

   opencode-agentbot

   on Oct 11, 2026 – with OpenCode Agent

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   Closing as not planned. Your test on @opencode/cli@2.0.26 showed that v2 reads UTF-16 files with a BOM correctly, so this only affects v1. v1 only gets critical fixes, and this one has a workaround: in PowerShell 5.1, use Out-File -Encoding utf8 or Set-Content -Encoding utf8 instead of >. The schema error you hit when importing a v1 export into v2 is tracked in #49314. Thanks for the detailed report and for checking v2. If this shows up again on v2, please open a new issue.