[BUG]: auto formatting causes apply_patch verification to fail #31422

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1. hesprs

   changed the title [-][BUG]: formatter causes `apply_patch` verification to fail[/-] [+][BUG]: auto formatting causes `apply_patch` verification to fail[/+] on Jun 8, 2026
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   rekram1-node

   on Jun 8, 2026
3. rekram1-node commented on Jun 8, 2026

   

   rekram1-node

   on Jun 8, 2026

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   auto formatting is off by default already.
4. rekram1-node

   closed this as not plannedon Jun 8, 2026
5. hesprs commented on Jun 9, 2026

   

   hesprs

   on Jun 9, 2026

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   Sorry for ignorance, I remember formatting was on by default for a period in the past.

   By the way, maybe when formatting enabled, OpenCode also needs to format the model's context? For example:

   1. model applies a patch
   2. formatter formats the file
   3. formatter also formats the corresponding file in the model's context.

   Or even better:

   1. Establish a dedicated files section in model context partitioning.
   2. When model reads a file, instead of adding raw text to the context, we add the file path to the "tracked files" list.
   3. The content of files in the files section is automatically refreshed when real file changes.

   This can ensure that whenever file changes, the model can always obtain the correct context. Otherwise, formatting / manual code edit midway the model's work would be catastrophic.
6. ricatix commented on Sep 17, 2026

   

   ricatix

   on Sep 17, 2026

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   I reproduced this deterministically on OpenCode 1.18.31 with an enabled Biome formatter, using the upstream oh-my-opencode-slim 2.2.21 pre-native rewritePatch verifier.

   Controlled A/B/C matrix (10 fresh fixture resets per condition):

   Condition	Accepted	Rejected
   patch 1 → patch 2, no formatter	10	0
   patch 1 → Biome → identical patch 2 with pre-format context	0	10
   patch 1 → Biome → re-read → regenerated patch 2	10	0

   The patch-2 payload was byte-identical between the first two conditions. Biome 2.4.8 changed:

   const config={enabled:true,count:3};

   to:

   const config = { enabled: true, count: 3 };

   The second condition then failed with verification_failed: Failed to find expected lines. Re-reading and regenerating against the actual post-format file restored acceptance in every run.

   I agree that leaving formatting disabled by default avoids the default-path regression, but users who intentionally enable a formatter still get deterministic stale model context after a successful edit. Could this issue be reconsidered for one of these narrower fixes?

   1. Return the post-format file content/diff in the successful edit tool result so the model sees the canonical state.
   2. Mark the edited file/context stale after formatting and require/trigger a fresh read before another edit against that file.
   3. At minimum, document or warn that enabling automatic formatting can invalidate subsequent patch context.

   Automatically rewriting historical conversation context seems riskier than exposing the post-format state through the tool result. The experiment only establishes this formatter-induced stale-context path; it does not claim all apply_patch failures have this cause.
7. hesprs commented on Sep 17, 2026

   

   hesprs

   on Sep 17, 2026

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   True, my previous formatting the model's context suggestion is terrible. It destroys KV cache catastrophically.