Move sibling-wasm lookup from pre-init to init-node's locateFile callback

Round 8 (argv[0] in pre-init) failed on Windows for the same reason
round 7 (execPath in pre-init) did:

    [pre-init diag] argv[0]=bun                              # not a path!
    [pre-init diag] execPath=B:\~BUN\root\<binary>.exe       # bunfs

Pre-init runs at module evaluation time. Inside a bun --compile binary
on Windows during that phase, both `process.argv[0]` and
`process.execPath` lie:

 - argv[0] is `"bun"` (the runtime name), not a real path
 - execPath is the *bunfs internal* path (`B:\~BUN\root\...`),
   not the disk path of the .exe

Both stabilize to real paths by the time main() runs (round 7's main()
diag confirmed that), but the SDK's eager Parser.init has already
fired by then with bad path data.

The fix: do the sibling-file lookup *inside the locateFile callback*
in code-map's init-node.ts. emscripten calls that callback during
Parser.init's async work, after process.execPath has stabilized to
the disk path. By then, `dirname(process.execPath) +
'tree-sitter.wasm'` resolves correctly.

- packages/code-map/src/init-node.ts: add a sibling-of-execPath
  check between the existing scriptDir fallback and the require.resolve
  fallback. Improves the thrown-error message to include the
  attempted execPath dir so future failures are easier to diagnose.
- cli/src/pre-init/tree-sitter-wasm.ts: keep the eager lookup as a
  best-effort fast path (it works on macOS/Linux where execPath is
  the disk path from module-load); on Windows it silently no-ops and
  the locateFile callback handles things lazily. Diagnostic dump
  remains gated on --smoke-tree-sitter so we can see what each phase
  thinks the paths are.

The SDK dist also needs rebuilding so the bundled init-node.ts copy
picks up this change — included in the diff.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: jahooma

cli/src/pre-init/tree-sitter-wasm.ts

@@ -42,6 +42,20 @@ const candidates = (
 
 const siblingPath = candidates.find((p) => existsSync(p))
 
+// Pre-init diagnostic — only fires when --smoke-tree-sitter is set so we
+// don't spam every run. We need to see what argv[0] / execPath looked
+// like at this exact phase on Windows: the round-7 main() diag showed
+// disk paths, but pre-init silently bailed, meaning module-init time
+// gives different values. argv[0] alone wasn't enough to fix it.
+if (process.argv.includes('--smoke-tree-sitter')) {
+  console.error(
+    `[pre-init diag] argv[0]=${process.argv[0]}\n` +
+      `[pre-init diag] execPath=${process.execPath}\n` +
+      `[pre-init diag] candidates=${JSON.stringify(candidates)}\n` +
+      `[pre-init diag] resolved siblingPath=${siblingPath ?? '<none>'}\n`,
+  )
+}
+
 if (siblingPath) {
   // Tell init-node.ts (in code-map / the SDK bundle) where the wasm
   // is. The locateFile callback there will hand this path to

packages/code-map/src/init-node.ts

@@ -47,6 +47,23 @@ function resolveTreeSitterWasm(scriptDir: string): string {
     return fallback
   }
 
+  // Sibling file next to the running binary. The CLI ships
+  // tree-sitter.wasm alongside `freebuff.exe` / `codebuff.exe` because
+  // bun --compile asset embedding was unreliable on Windows. We do this
+  // lookup *here* (not in pre-init) on purpose: inside a bun --compile
+  // binary on Windows, `process.execPath` returns the bunfs internal
+  // path during early module evaluation and only switches to the disk
+  // path later. emscripten calls this locateFile callback during
+  // Parser.init's async work, by which time execPath has stabilized.
+  try {
+    const sibling = path.join(path.dirname(process.execPath), 'tree-sitter.wasm')
+    if (fs.existsSync(sibling)) {
+      return sibling
+    }
+  } catch {
+    // process.execPath may be unavailable in exotic runtimes; fall through.
+  }
+
   try {
     const pkgDir = path.dirname(require.resolve('web-tree-sitter'))
     const wasm = path.join(pkgDir, 'tree-sitter.wasm')
@@ -61,7 +78,7 @@ function resolveTreeSitterWasm(scriptDir: string): string {
     ? ` (env ${TREE_SITTER_WASM_ENV_VAR}=${override} did not exist)`
     : ''
   throw new Error(
-    `Internal error: tree-sitter.wasm not found (looked at scriptDir=${scriptDir} and via web-tree-sitter package${overrideDiagnostic}). Set ${TREE_SITTER_WASM_ENV_VAR} or ensure the file is included in your deployment bundle.`,
+    `Internal error: tree-sitter.wasm not found (looked at scriptDir=${scriptDir}, dirname(process.execPath)=${path.dirname(process.execPath)}, and via web-tree-sitter package${overrideDiagnostic}). Set ${TREE_SITTER_WASM_ENV_VAR} or ensure the file is included in your deployment bundle.`,
   )
 }