convertToModelMessages replaces application tool result metadata with call metadata

Finding: In vercel/ai, on published ai@7.0.137 and upstream commit ba05943 (as reported), convertToModelMessages() reportedly gives the model tool-result message the call metadata instead of the distinct result metadata for application-executed tool results. Source: https://github.com/vercel/ai/issues/22579 Reported conditions: a synthetic stream built with readUIMessageStream has a tool-input-available chunk with providerMetadata {example:{phase:'call'}} and a tool-output-available chunk with different providerMetadata {example:{phase:'result'}}. The UI message part keeps the two separately (resultProviderMetadata equals the result metadata). After convertToModelMessages([message]), the assistant tool-call providerOptions match the call metadata, as expected, but the tool-result providerOptions do not match the result metadata, so the final assertion in the reporter's script fails. The reporter says the script uses no model or network calls. No exact error message is reported; the failure is an assertion mismatch. Reported cause (hypothesis, not maintainer-confirmed): in packages/ai/src/ui/convert-to-model-messages.ts, the branch that creates the separate role:'tool' message for output-available/output-error populates providerOptions solely from callProviderMetadata. The provider-executed branch reportedly already uses resultProviderMetadata with callProviderMetadata as fallback. A contributor-association automation comment says it reproduced the loss on main for static and dynamic tool parts, for available and error results, and that the fallback is correct when result metadata is absent (https://github.com/vercel/ai/issues/22579#issuecomment-6101839909). Status: the reporter's proposed fix (use result metadata for application-executed results, keep call metadata as fallback, keep call metadata on the tool-call) is explicitly not implemented. No fix commit, merged PR or release is supplied, and no workaround is source-supported. A reproduction PR is only linked in a comment. Diagnostic implication, conditional: if your app round-trips UI messages containing application-executed tool results and relies on result-specific provider options, they may be replaced by call-level options in the model prompt on the affected versions. Limitation: this is an external report with automation corroboration; KFA did not reproduce it. Comments are partially covered.