[pikann]

Summary

Fixes plugin builds under TinyGo, which is the recommended compiler per the README but was previously broken in two ways when actually used against the host runtime.

• wasm_exports.go: Export the SDK's allocator functions as paca_malloc/paca_free instead of malloc/free. TinyGo's bundled wasi-libc already exports its own malloc/free, so exporting under the same names produced a WASM module with duplicate exports — invalid per spec and rejected at load time.
• wasm_backends.go: Shrink mallocBuffer from 10MB to 1MB to match services/api's DefaultResourceLimits.MaxRequestBodyBytes (paca/services/api/internal/platform/plugin/runtime.go). The host already rejects any payload larger than that before writing to this buffer, so 10MB was unnecessary — and since every loaded plugin gets its own independent copy of this buffer, the smaller size meaningfully reduces the host's per-plugin memory footprint.
• README.md: Update the build instructions to use tinygo build -target=wasip1 -buildmode=c-shared. -buildmode=c-shared is required, not optional — without it, TinyGo doesn't wire up the WASI reactor entry point (_initialize) this SDK's runtime depends on, and the plugin panics at load with "//go:wasmexport function called before runtime initialization" (it still compiles fine without the flag, so this only surfaces once the host actually loads the plugin). Also documents the standard-Go fallback for TinyGo stdlib gaps, and a required workaround (wrap in a closure) for plugins that declare their own //go:wasmimport host function and pass it to CallHostFunction, since TinyGo doesn't support taking the address of a go:wasmimport function.

Test plan

• Build a plugin with tinygo build -target=wasip1 -buildmode=c-shared and confirm it loads and handles requests against the host runtime
• Confirm the module has no duplicate malloc/free exports
• Confirm CallHostFunction with a closure-wrapped //go:wasmimport function builds under both TinyGo and standard Go

[greptile-apps]

Greptile Summary

This PR updates the documented WASI build process for TinyGo and changes WASM memory management to avoid TinyGo allocator-export collisions.

• Renames the guest allocator exports from malloc/free to paca_malloc/paca_free.
• Reduces the fixed allocator arena from 10 MiB to 1 MiB.
• Adds TinyGo reactor-mode guidance and a standard Go fallback to the README.

Confidence Score: 3/5

The PR should not merge until the allocator can hold simultaneously live request and response data and the documented standard Go minimum is corrected.

A valid near-limit request can exhaust the newly reduced shared arena while its response is packed, and users on the newly advertised Go 1.21–1.23 range cannot build the documented standard-Go fallback.

Files Needing Attention: wasm_backends.go, README.md

Important Files Changed

Filename	Overview
wasm_backends.go	Reduces the shared bump-allocation arena to 1 MiB, which cannot hold a near-limit request and its response simultaneously.
wasm_exports.go	Renames allocator exports for TinyGo and retains the response allocation flow that shares the request arena until reset.
README.md	Adds useful TinyGo reactor guidance but incorrectly advertises the standard Go c-shared WASI path as supported from Go 1.21.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart LR
  H[Host] -->|paca_malloc request size| A[1 MiB bump arena]
  H -->|write request| A
  H -->|HandleRequest| P[Plugin handler]
  P -->|serialize response| R[packWASMResult]
  R -->|wasmMalloc response size| A
  A -->|combined size exceeds 1 MiB| F[Allocation returns 0]
  H -->|copy response, then ResetAllocator| X[Reset arena]

Loading

_{Reviews (1): Last reviewed commit: "feat: update README and WASM memory mana..." | Re-trigger Greptile}