WASM Node.js polyfills for node:fs, node:path, node:os #12

Parent: #9

Summary

Extend Tier 1 WASM plugins to support node:fs, node:path, and node:os via polyfills in the shim and new host functions.

Blocked By

Nothing — can start immediately.

Deliverables

C1. Shim Polyfills

Modify: crates/openclaw-bridge/src/shim.rs

Add to generated shim header:

• require() polyfill dispatching node:fs → _virtualFs, node:path → _virtualPath, node:os → _virtualOs
• _virtualFs: readFileSync → hostReadFile, writeFileSync → hostWriteFile, existsSync, mkdirSync, readdirSync, statSync, unlinkSync
• _virtualPath: pure JS join, resolve, dirname, basename, extname, sep, normalize
• _virtualOs: homedir() → /data, platform() → "wasm", tmpdir() → /tmp

C2. New Host Functions

Modify: crates/astrid-plugins/src/wasm/host_functions.rs

Add (all through resolve_within_workspace() + SecurityGate):

• astrid_fs_exists(path: PTR) → i32
• astrid_fs_mkdir(path: PTR)
• astrid_fs_readdir(path: PTR) → PTR (JSON array)
• astrid_fs_stat(path: PTR) → PTR (JSON: {size, isDir, mtime})
• astrid_fs_unlink(path: PTR)

Update alphabetical host function index and QuickJS dispatch table.

C3. Transpiler Relaxation

Modify: crates/openclaw-bridge/src/transpiler.rs

Allow imports from node:fs, node:path, node:os (polyfilled). Rewrite to require() calls during transpilation. Continue rejecting other runtime imports.

Acceptance Criteria

• WASM plugin calling require("node:fs").readFileSync(...) works through host functions
• node:path operations work as pure JS (no host function needed)
• node:os returns virtual values (homedir → /data)
• 5 new host functions registered in correct alphabetical order
• Shim dispatch table and QuickJS metadata updated
• Transpiler allows node:fs, node:path, node:os imports