feat(go/ai): support middleware in dotprompt frontmatter#5229
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Wire the dotprompt `use:` field through the Go prompt loader so middleware references travel from frontmatter to runtime execution, mirroring the JS implementation. Entries may be a bare middleware name or a map with `name` and optional `config`. References are carried through `configsToRefs` via an unexported `middlewareRefArg` adapter that is stripped before reaching `resolveRefs`, routing resolution through the registry (rather than the in-process fast path) so config payloads propagate untouched.
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This pull request introduces support for lazy middleware references in dotprompt frontmatter, allowing middleware to be resolved via the registry. It includes the necessary internal types, parsing logic, and comprehensive test coverage. I have provided a suggestion to simplify the error handling in prompt.go by removing redundant error wrapping.
MichaelDoyle
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May 5, 2026
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I have't verified in the Dev UI yet, but this matches what I expect.
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Adds Go runtime support for the dotprompt
use:frontmatter field, mirroring the JS-side work in #5223. Each entry may be a bare middleware name or a map withnameand optionalconfig, matching the TypeScript shape.The references travel through
[]Middlewarevia an unexportedmiddlewareRefArgadapter, whichconfigsToRefsstrips before constructing theMiddlewareRef. This routes resolution through the registry-lookup path rather than the in-process fast path used for Go-defined middleware, so JSON-shaped configs from YAML propagate untouched.Errors surface at load time for malformed input (non-list
use:, missingname, empty entries) and at execute time for names that do not resolve in the registry.Checklist:
go/ai/middleware_test.goandgo/ai/prompt_test.gocovering the parser, the lazy adapter, end-to-end load + execute, unregistered names, and invalid shapes)