feat: discover the nearest tsconfig.json that claims each file

Cargo.toml

@@ -10,6 +10,7 @@ publish = false
 crate-type = ["cdylib"]
 
 [dependencies]
+memchr = "2"
 napi = { version = "3.12.2", default-features = false, features = ["serde-json", "napi3"] }
 napi-derive = { version = "3.6.3", default-features = false, features = ["type-def"] }
 oxc = { version = "0.148.0", features = [
@@ -22,6 +23,7 @@ oxc_resolver = { version = "11.24.3" }
 oxc_sourcemap = "8"
 phf = { version = "0.14", features = ["macros"] }
 serde_json = "1"
+simdutf8 = "0.1"
 tracing = "0.1"
 tracing-subscriber = { version = "0.3", default-features = false, features = [
   "std",

README.md

@@ -77,9 +77,26 @@ transform hook.
 
 ## Configuration
 
-By default, `oxc-node` reads `tsconfig.json` from the current working directory.
-Set `OXC_TSCONFIG_PATH` to use a different file. `TS_NODE_PROJECT` is also
-supported and takes precedence when both variables are set.
+By default, each file is governed by the nearest `tsconfig.json` in its own
+ancestor directories that claims it through `files`, `include`, `exclude` or a
+project reference — the same rule `tsc` follows. A file in a sub-project without
+its own `tsconfig.json` therefore inherits the workspace root one, and a file
+that no config claims is compiled with no options at all.
+
+`include` only covers `.js`, `.jsx`, `.mjs` and `.cjs` files when `allowJs` is
+enabled, so by default no config claims them and they are compiled with no
+options. For **module resolution** they are matched as if they were TypeScript,
+which keeps path aliases working from JavaScript without `allowJs`.
+
+A `tsconfig.json` that fails to parse stops the search: that file and every
+directory above it are skipped, and the file is compiled with no options.
+Comments and trailing commas are fine — only genuinely invalid JSON does this.
+Run with `OXC_LOG=debug` to see which config was picked for each file.
+
+Set `OXC_TSCONFIG_PATH` to pin one config for every file instead. `TS_NODE_PROJECT`
+is also supported and takes precedence when both variables are set; an empty value
+counts as unset. Naming a file that does not exist disables `tsconfig.json`
+handling entirely rather than falling back to the search above.
 
 The supported `tsconfig.json` options are used for resolution and
 transformation. These include path aliases, module and JSX settings, legacy