diff --git a/.github/workflows/host-checks.yml b/.github/workflows/host-checks.yml
index 5e6e2be..8b64b78 100644
--- a/.github/workflows/host-checks.yml
+++ b/.github/workflows/host-checks.yml
@@ -60,6 +60,9 @@ jobs:
       - name: Cargo clippy (warnings are errors)
         run: cargo clippy --all-targets --locked -- -D warnings
 
+      - name: Cargo clippy with Wasm host tools
+        run: cargo clippy --bin hyperlight-unikraft --tests --locked --features wasm-host-fns -- -D warnings
+
       - name: Enable KVM permissions
         working-directory: .
         run: |
@@ -75,6 +78,11 @@ jobs:
           RUST_BACKTRACE: '1'
         run: cargo test --all-targets --locked
 
+      - name: Cargo test with Wasm host tools
+        env:
+          RUST_BACKTRACE: '1'
+        run: cargo test --bin hyperlight-unikraft --locked --features wasm-host-fns wasm_host_fns::tests
+
   host-checks-passed:
     if: always()
     needs: [checks]
diff --git a/README.md b/README.md
index 2a4b0e9..49d41e4 100644
--- a/README.md
+++ b/README.md
@@ -49,7 +49,7 @@ This project enables running Linux applications (Python, Node.js, Go, Rust, C/C+
 
 ### Key Features
 
-- **Thin, opt-in host surface** — by default, the guest has no access to the host filesystem, network, or any host functions. When you enable features like `--mount`, `--net`, or `--enable-tools`, a single `__dispatch` JSON-RPC bridge is registered as the only guest→host channel. See [HOST_FUNCTIONS.md](HOST_FUNCTIONS.md) for the full list of dispatchable operations
+- **Thin, opt-in host surface** — by default, the guest has no access to the host filesystem, network, or any host functions. When you enable features like `--mount`, `--net`, `--enable-tools`, or `--tool`, a single `__dispatch` JSON-RPC bridge is registered as the only guest→host channel. See [host_functions.md](docs/host_functions.md) for the full list of dispatchable operations
 - **Identity-mapped memory** - Simplified memory layout (vaddr == paddr)
 - **Generic cmdline mechanism** - Pass arguments to any application via `-- arg1 arg2 ...`
 - **Fast cold start** - Hyperlight's lightweight design enables millisecond startup times
@@ -281,7 +281,19 @@ Options:
   -m, --memory <MEMORY>        Memory allocation (e.g., 256Mi, 512Mi, 1Gi) [default: 512Mi]
       --stack <STACK>          Stack size (e.g., 8Mi) [default: 8Mi]
   -q, --quiet                  Quiet mode — suppress host-side status messages
-      --enable-tools           Enable tool dispatch via __dispatch host function
+      --enable-tools           Register the built-in echo tool
+      --tool <NAME=WASM>        Register a WASIp1 module as a host tool (requires wasm-host-fns)
+      --tool-wasi-dir <HOST[:GUEST]>
+                               Preopen a read-write host directory for Wasm tools
+      --tool-wasi-dir-ro <HOST[:GUEST]>
+                               Preopen a read-only host directory for Wasm tools
+      --tool-wasi-env <KEY=VALUE>
+                               Set an environment variable for Wasm tools
+      --tool-wasi-env-inherit <KEY>
+                               Inherit one host environment variable into Wasm tools
+      --tool-wasi-fuel <FUEL>  Fuel units available to each Wasm tool call [default: 100000000]
+      --tool-wasi-output-limit <SIZE>
+                               Maximum stdout or stderr captured from one Wasm tool call [default: 1Mi]
       --mount <HOST[:GUEST]>   Preopen a host directory for the guest's sandboxed filesystem
                                (repeatable; default guest path: /host)
       --net                    Enable guest networking (off by default)
@@ -297,6 +309,17 @@ Options:
   -V, --version                Print version
 ```
 
+### Wasm host tools
+
+Build the CLI with the optional `wasm-host-fns` feature to register host-side custom tools from WASIp1 modules:
+
+```bash
+cargo build --manifest-path host/Cargo.toml --release --features wasm-host-fns --bin hyperlight-unikraft
+hyperlight-unikraft kernel --initrd app.cpio --tool greet=./greet.wasm
+```
+
+The guest still calls the existing `__dispatch` envelope, for example `{"name":"greet","args":{"who":"Ada"}}`. The Wasm handler runs on the host in Wasmtime, receives that request JSON on stdin, and writes either a raw JSON result or `{"result": ...}` / `{"error": "..."}` to stdout. WASI filesystem and environment access are off unless granted with `--tool-wasi-dir`, `--tool-wasi-dir-ro`, `--tool-wasi-env`, or `--tool-wasi-env-inherit`.
+
 ## Project Structure
 
 ```
diff --git a/docs/host_functions.md b/docs/host_functions.md
index 3c5b1e3..b1aec6a 100644
--- a/docs/host_functions.md
+++ b/docs/host_functions.md
@@ -15,7 +15,7 @@ Implementation lives in [`host/src/lib.rs`](../host/src/lib.rs). Guest-side call
 | `fs_*` tools | **Off** | `--mount HOST[:GUEST]` (repeatable) |
 | `net_*` tools | **Off** | `--net`, `--net-allow`, or `--net-block` |
 | Inbound listen | **Off** | `--port PORT` (requires network enabled) |
-| Custom tools | **Off** | `--enable-tools` + `SandboxBuilder::tool()` |
+| Custom tools | **Off** | `--tool NAME=WASM` with `wasm-host-fns`, `SandboxBuilder::tool()`, or legacy/demo `--enable-tools` echo |
 
 With **no flags**, the guest cannot reach the host filesystem or network through dispatch. Only internal plumbing (`__hl_exit`, `__hl_sleep`) is wired.
 
@@ -85,7 +85,18 @@ hyperlight-unikraft KERNEL [--initrd CPIO] [options] [-- APP_ARGS...]
 | `--net-allow HOST_OR_IP` | Allow-list outbound destinations (implies `--net`). Repeatable. |
 | `--net-block HOST_OR_IP` | Block-list; all other destinations allowed (implies `--net`). Mutually exclusive with `--net-allow`. |
 | `--port PORT` | Allow `net_bind` / listen on `PORT` (implies `--net`). Without `--port`, outbound-only: bind is rejected. |
-| `--enable-tools` | Enables custom tool registration. Registers a built-in `echo` tool (used by the `python-tools` example). Library users add their own tools via `SandboxBuilder::tool()`. |
+| `--enable-tools` | Registers only the built-in `echo` demo tool. It does not load user code; prefer `--tool NAME=WASM` for CLI custom tools or `SandboxBuilder::tool()` for library users. |
+| `--tool NAME=WASM` | With the Cargo feature `wasm-host-fns`, registers `WASM` as a host-side WASIp1 custom tool named `NAME`. Repeatable. |
+| `--tool-wasi-dir HOST[:GUEST]` | Preopens a read-write host directory for every CLI Wasm tool. Default guest path is `/host`. Repeatable. |
+| `--tool-wasi-dir-ro HOST[:GUEST]` | Preopens a read-only host directory for every CLI Wasm tool. Default guest path is `/host`. Repeatable. |
+| `--tool-wasi-env KEY=VALUE` | Sets an environment variable for every CLI Wasm tool. Repeatable. |
+| `--tool-wasi-env-inherit KEY` | Copies one host environment variable into every CLI Wasm tool. Repeatable. |
+| `--tool-wasi-fuel FUEL` | Sets the instruction-fuel budget for each call to every CLI Wasm tool. Default `100000000`. |
+| `--tool-wasi-output-limit SIZE` | Caps captured stdout and stderr for each call to every CLI Wasm tool. Default `1Mi`. |
+
+`--tool-wasi-*` flags configure the Wasmtime/WASI sandbox for Wasm custom tools only. They do not expose the guest `--mount` filesystem, and they do not change the `fs_*` handlers used by `lib/hostfs`.
+
+The CLI currently applies the same Wasm filesystem, environment, fuel, and output settings to every `--tool` registered in one invocation. If tools need different permissions or limits, do not grant the union to all handlers; that requires a narrower per-tool configuration surface or a separate host integration.
 
 **Mount rules (host-enforced before boot):**
 
@@ -189,7 +200,38 @@ Sockets are host-side (`socket2`); the guest sees opaque numeric **`fd`** handle
 
 ## Custom tools
 
-**CLI:** `--enable-tools` registers a built-in `echo` tool (returns `args` unchanged) used by the [`python-tools` example](../examples/python-tools). The primary purpose of `--enable-tools` is to demonstrate custom host function registration via the API.
+**CLI demo tool:** `--enable-tools` registers only a built-in `echo` tool that returns `args` unchanged. It is useful as a smoke test and compatibility path, but it is not the CLI extension mechanism for user-provided host functions. CLI examples should prefer a Wasm `echo.wasm` registered with `--tool echo=...`; library examples should register an echo handler with `SandboxBuilder::tool()`.
+
+**CLI Wasm tools:** build with the optional feature and pass one or more `--tool` flags:
+
+```bash
+cargo build --manifest-path host/Cargo.toml --features wasm-host-fns --bin hyperlight-unikraft
+hyperlight-unikraft kernel --initrd app.cpio --tool greet=./greet.wasm
+```
+
+Each `--tool NAME=WASM` module is compiled and linked before VM boot, then invoked as a fresh WASIp1 command for every matching guest `__dispatch` call. The handler receives the existing dispatch request on stdin:
+
+```json
+{"name":"NAME","args":<json_value>}
+```
+
+The handler writes JSON to stdout. It may write either a raw JSON result value or the normal dispatch envelope:
+
+```json
+{"result":<json_value>}
+```
+
+```json
+{"error":"message"}
+```
+
+A raw value is treated as the tool result. A single-key `result` envelope is unwrapped. A single-key `error` envelope becomes the outer `__dispatch` error response. Empty stdout returns JSON null.
+
+Wasm tools are separate from the built-in `fs_*` and `net_*` dispatch handlers. `--mount` controls what the guest can access through `lib/hostfs`; `--tool-wasi-dir*` controls what the host-side Wasm handler can access through its own WASI filesystem view.
+
+WASI capabilities are denied by default except stdio used for the protocol, clocks, and random. Use `--tool-wasi-dir`, `--tool-wasi-dir-ro`, `--tool-wasi-env`, and `--tool-wasi-env-inherit` to grant explicit filesystem and environment access to handlers. These grants and the `--tool-wasi-fuel` / `--tool-wasi-output-limit` settings apply to every CLI Wasm tool registered by the process. Tool names beginning with `__`, `fs_`, or `net_` are reserved.
+
+**Why WASIp1 command modules today?** The current CLI maps one `--tool NAME=WASM` flag to one tool name and one fresh handler invocation. WASIp1 keeps that ABI small: JSON request on stdin, JSON response on stdout, no long-lived reactor state, and broad language/toolchain support. Component-model or reactor-style handlers could support a future `--tools component.wasm` shape with multiple exported tools and auto-registration, but that would need a separate registration and lifecycle model; it is not the current ABI.
 
 **Library:**
 
@@ -199,7 +241,7 @@ Sandbox::builder("kernel")
     .build()?;
 ```
 
-Custom handlers run with the same JSON request/response envelope as built-in tools.
+`SandboxBuilder::tool()` handlers receive the inner `args` JSON value from the dispatch request; the registry has already matched the outer `name`. Handler return values become the `result` field in the outer `__dispatch` response, and handler errors become `{"error": "..."}`.
 
 ---
 
@@ -214,6 +256,8 @@ Custom handlers run with the same JSON request/response envelope as built-in too
 | `fs_list` entries | 100 000 |
 | `net_send` / `net_sendto` | 1 MiB decoded bytes |
 | `__hl_sleep` | 60 s |
+| Wasm tool fuel | 100 000 000 instructions per call by default; configurable with `--tool-wasi-fuel`; same value applies to every CLI Wasm tool |
+| Wasm tool stdout / stderr | 1 MiB each per call by default; configurable with `--tool-wasi-output-limit`; same value applies to every CLI Wasm tool |
 | Open host sockets | 1024 per sandbox |
 | AllowList learned DNS IPs | 256 |
 
@@ -242,6 +286,14 @@ Custom handlers run with the same JSON request/response envelope as built-in too
 - A compromised guest can invoke any **registered** tool name; do not register powerful custom tools unless needed.
 - Payload size is capped; malformed JSON fails closed with an error response.
 
+**When `--tool` is used with `wasm-host-fns`:**
+
+- Handler code runs on the host inside Wasmtime, not inside the Unikraft VM.
+- WASI filesystem and environment access are capability-based and off unless explicitly granted with `--tool-wasi-*` flags.
+- CLI Wasm capability and limit flags apply to every registered Wasm tool; avoid combining handlers with different privilege needs in one invocation.
+- Fuel limits bound Wasm instruction execution, but do not turn filesystem operations into a full wall-clock timeout.
+- Handlers are untrusted code from the host operator's filesystem; only load modules you intend to grant these capabilities to.
+
 **Not exposed via dispatch:** Host shell, arbitrary process spawn, unrestricted host `exec`, or kernel modules — only the tools listed above.
 
 **Operators should:** Use minimal flags, allow-lists over `--net` where possible, mount least-privilege directories, and run guests with the smallest initrd/runtime required.
diff --git a/host/Cargo.lock b/host/Cargo.lock
index 4ec277d..f09ff69 100644
--- a/host/Cargo.lock
+++ b/host/Cargo.lock
@@ -2,6 +2,15 @@
 # It is not intended for manual editing.
 version = 4
 
+[[package]]
+name = "addr2line"
+version = "0.25.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1b5d307320b3181d6d7954e663bd7c774a838b8220fe0593c86d9fb09f498b4b"
+dependencies = [
+ "gimli",
+]
+
 [[package]]
 name = "adler2"
 version = "2.0.1"
@@ -17,6 +26,18 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "allocator-api2"
+version = "0.2.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "683d7910e743518b0e34f1186f92494becacb047c7b6bf616c96772180fef923"
+
+[[package]]
+name = "ambient-authority"
+version = "0.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e9d4ee0d472d1cd2e28c97dfa124b3d8d992e10eb0a035f33f5d12e3a177ba3b"
+
 [[package]]
 name = "android_system_properties"
 version = "0.1.5"
@@ -82,6 +103,12 @@ version = "1.0.102"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7f202df86484c868dbad7eaa557ef785d5c66295e41b460ef922eca0723b842c"
 
+[[package]]
+name = "arbitrary"
+version = "1.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c3d036a3c4ab069c7b410a2ce876bd74808d2d0888a82667669f8e783a898bf1"
+
 [[package]]
 name = "arrayref"
 version = "0.3.9"
@@ -94,6 +121,17 @@ version = "0.7.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7c02d123df017efcdfbd739ef81735b36c5ba83ec3c59c80a9d7ecc718f92e50"
 
+[[package]]
+name = "async-trait"
+version = "0.1.89"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9035ad2d096bed7955a320ee7e2230574d28fd3c3a0f186cbea1ff3c7eed5dbb"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "autocfg"
 version = "1.5.0"
@@ -166,6 +204,9 @@ name = "bumpalo"
 version = "3.19.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5dd9dc738b7a8311c7ade152424974d8115f2cdad61e8dab8dac9f2362298510"
+dependencies = [
+ "allocator-api2",
+]
 
 [[package]]
 name = "bytemuck"
@@ -193,6 +234,84 @@ version = "1.11.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1e748733b7cbc798e1434b6ac524f0c1ff2ab456fe201501e6497c8417a4fc33"
 
+[[package]]
+name = "cap-fs-ext"
+version = "3.4.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d5528f85b1e134ae811704e41ef80930f56e795923f866813255bc342cc20654"
+dependencies = [
+ "cap-primitives",
+ "cap-std",
+ "io-lifetimes",
+ "windows-sys 0.52.0",
+]
+
+[[package]]
+name = "cap-net-ext"
+version = "3.4.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "20a158160765c6a7d0d8c072a53d772e4cb243f38b04bfcf6b4939cfbe7482e7"
+dependencies = [
+ "cap-primitives",
+ "cap-std",
+ "rustix 1.1.4",
+ "smallvec",
+]
+
+[[package]]
+name = "cap-primitives"
+version = "3.4.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b6cf3aea8a5081171859ef57bc1606b1df6999df4f1110f8eef68b30098d1d3a"
+dependencies = [
+ "ambient-authority",
+ "fs-set-times",
+ "io-extras",
+ "io-lifetimes",
+ "ipnet",
+ "maybe-owned",
+ "rustix 1.1.4",
+ "rustix-linux-procfs",
+ "windows-sys 0.52.0",
+ "winx",
+]
+
+[[package]]
+name = "cap-rand"
+version = "3.4.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d8144c22e24bbcf26ade86cb6501a0916c46b7e4787abdb0045a467eb1645a1d"
+dependencies = [
+ "ambient-authority",
+ "rand 0.8.6",
+]
+
+[[package]]
+name = "cap-std"
+version = "3.4.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b6dc3090992a735d23219de5c204927163d922f42f575a0189b005c62d37549a"
+dependencies = [
+ "cap-primitives",
+ "io-extras",
+ "io-lifetimes",
+ "rustix 1.1.4",
+]
+
+[[package]]
+name = "cap-time-ext"
+version = "3.4.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "def102506ce40c11710a9b16e614af0cde8e76ae51b1f48c04b8d79f4b671a80"
+dependencies = [
+ "ambient-authority",
+ "cap-primitives",
+ "iana-time-zone",
+ "once_cell",
+ "rustix 1.1.4",
+ "winx",
+]
+
 [[package]]
 name = "cc"
 version = "1.2.53"
@@ -225,7 +344,7 @@ checksum = "6f8d983286843e49675a4b7a2d174efe136dc93a18d69130dd18198a6c167601"
 dependencies = [
  "cfg-if",
  "cpufeatures 0.3.0",
- "rand_core",
+ "rand_core 0.10.0",
 ]
 
 [[package]]
@@ -279,6 +398,15 @@ version = "0.7.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c3e64b0cc0439b12df2fa678eae89a1c56a529fd067a9115f7827f1fffd22b32"
 
+[[package]]
+name = "cobs"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0fa961b519f0b462e3a3b4a34b64d119eeaca1d59af726fe450bbba07a9fc0a1"
+dependencies = [
+ "thiserror 2.0.18",
+]
+
 [[package]]
 name = "colorchoice"
 version = "1.0.4"
@@ -315,6 +443,144 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "cranelift-assembler-x64"
+version = "0.123.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "de2be1bdbf929c2a2242cbbe15d6583c56f1cc723c6c8452d0179362de28c9d5"
+dependencies = [
+ "cranelift-assembler-x64-meta",
+]
+
+[[package]]
+name = "cranelift-assembler-x64-meta"
+version = "0.123.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9a0336914de11298290783a95a9a7154b894da601659eb5f8f8bc62d1bea98f8"
+dependencies = [
+ "cranelift-srcgen",
+]
+
+[[package]]
+name = "cranelift-bforest"
+version = "0.123.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fb972cba51a52c1b2a329fec993b911e4d1f9cfab3795811a319b6746c28e014"
+dependencies = [
+ "cranelift-entity",
+]
+
+[[package]]
+name = "cranelift-bitset"
+version = "0.123.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "642c920666bfed9aebca39d8c6e7cb76f09314cc7a4074b1db5edcccdde771b9"
+dependencies = [
+ "serde",
+ "serde_derive",
+]
+
+[[package]]
+name = "cranelift-codegen"
+version = "0.123.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0e1231caaeee3d2363d9b2dba9d6c1f7ff835b8ede6612fba98120af73df44bd"
+dependencies = [
+ "bumpalo",
+ "cranelift-assembler-x64",
+ "cranelift-bforest",
+ "cranelift-bitset",
+ "cranelift-codegen-meta",
+ "cranelift-codegen-shared",
+ "cranelift-control",
+ "cranelift-entity",
+ "cranelift-isle",
+ "gimli",
+ "hashbrown 0.15.5",
+ "log",
+ "pulley-interpreter",
+ "regalloc2",
+ "rustc-hash",
+ "serde",
+ "smallvec",
+ "target-lexicon",
+ "wasmtime-internal-math",
+]
+
+[[package]]
+name = "cranelift-codegen-meta"
+version = "0.123.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "eb83e89be8b413e4f7a4215a02d5c5f3e6f04b1060f5db293dd1007b2871dcf5"
+dependencies = [
+ "cranelift-assembler-x64-meta",
+ "cranelift-codegen-shared",
+ "cranelift-srcgen",
+ "heck",
+ "pulley-interpreter",
+]
+
+[[package]]
+name = "cranelift-codegen-shared"
+version = "0.123.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9d14f8068a98f0a85ffa63dc5fe73cb486a955adbe7311465d13cde54c656d5f"
+
+[[package]]
+name = "cranelift-control"
+version = "0.123.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c070aee9312b9736028e99b58d45e1099683386082af38529d5e2ce8c76648f3"
+dependencies = [
+ "arbitrary",
+]
+
+[[package]]
+name = "cranelift-entity"
+version = "0.123.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f2d619bb3d14251e96dc9b6a846d6955d78048a168cc3876eb2b789b855c1c22"
+dependencies = [
+ "cranelift-bitset",
+ "serde",
+ "serde_derive",
+]
+
+[[package]]
+name = "cranelift-frontend"
+version = "0.123.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2350fcff24d78be5e4201e1eeb4b306e474b9f21e452722b21ffc4f773e8d49a"
+dependencies = [
+ "cranelift-codegen",
+ "log",
+ "smallvec",
+ "target-lexicon",
+]
+
+[[package]]
+name = "cranelift-isle"
+version = "0.123.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8bdc2b14d7491c53c2989b967b4c07511374733abbc01a895fb01ea31e97bfc8"
+
+[[package]]
+name = "cranelift-native"
+version = "0.123.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e98dbe1326d0001a17b3b0675e3adafcfbd0e7f25f1f845a2f1bb9ce3029f359"
+dependencies = [
+ "cranelift-codegen",
+ "libc",
+ "target-lexicon",
+]
+
+[[package]]
+name = "cranelift-srcgen"
+version = "0.123.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "36d7af563cd300c8a1e4e64387929b40e32867112143f0a0e1ce90f977ce4a41"
+
 [[package]]
 name = "crc32fast"
 version = "1.5.0"
@@ -391,6 +657,33 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "either"
+version = "1.16.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "91622ff5e7162018101f2fea40d6ebf4a78bbe5a49736a2020649edf9693679e"
+
+[[package]]
+name = "embedded-io"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ef1a6892d9eef45c8fa6b9e0086428a2cca8491aca8f787c534a3d6d0bcb3ced"
+
+[[package]]
+name = "embedded-io"
+version = "0.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "edd0f118536f44f5ccd48bcb8b111bdc3de888b58c74639dfb034a357d0f206d"
+
+[[package]]
+name = "encoding_rs"
+version = "0.8.35"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "75030f3c4f45dafd7586dd6780965a8c7e8e285a5ecb86713e63a79c5b2766f3"
+dependencies = [
+ "cfg-if",
+]
+
 [[package]]
 name = "equivalent"
 version = "1.0.2"
@@ -407,6 +700,29 @@ dependencies = [
  "windows-sys 0.61.2",
 ]
 
+[[package]]
+name = "fallible-iterator"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2acce4a10f12dc2fb14a218589d4f1f62ef011b2d0cc4b3cb1bba8e94da14649"
+
+[[package]]
+name = "fastrand"
+version = "2.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9f1f227452a390804cdb637b74a86990f2a7d7ba4b7d5693aac9b4dd6defd8d6"
+
+[[package]]
+name = "fd-lock"
+version = "4.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0ce92ff622d6dadf7349484f42c93271a0d49b7cc4d466a936405bacbe10aa78"
+dependencies = [
+ "cfg-if",
+ "rustix 1.1.4",
+ "windows-sys 0.52.0",
+]
+
 [[package]]
 name = "filetime"
 version = "0.2.29"
@@ -458,6 +774,77 @@ dependencies = [
  "percent-encoding",
 ]
 
+[[package]]
+name = "fs-set-times"
+version = "0.20.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "94e7099f6313ecacbe1256e8ff9d617b75d1bcb16a6fddef94866d225a01a14a"
+dependencies = [
+ "io-lifetimes",
+ "rustix 1.1.4",
+ "windows-sys 0.52.0",
+]
+
+[[package]]
+name = "futures"
+version = "0.3.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8b147ee9d1f6d097cef9ce628cd2ee62288d963e16fb287bd9286455b241382d"
+dependencies = [
+ "futures-channel",
+ "futures-core",
+ "futures-io",
+ "futures-sink",
+ "futures-task",
+ "futures-util",
+]
+
+[[package]]
+name = "futures-channel"
+version = "0.3.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "07bbe89c50d7a535e539b8c17bc0b49bdb77747034daa8087407d655f3f7cc1d"
+dependencies = [
+ "futures-core",
+ "futures-sink",
+]
+
+[[package]]
+name = "futures-core"
+version = "0.3.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7e3450815272ef58cec6d564423f6e755e25379b217b0bc688e295ba24df6b1d"
+
+[[package]]
+name = "futures-io"
+version = "0.3.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cecba35d7ad927e23624b22ad55235f2239cfa44fd10428eecbeba6d6a717718"
+
+[[package]]
+name = "futures-sink"
+version = "0.3.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c39754e157331b013978ec91992bde1ac089843443c49cbc7f46150b0fad0893"
+
+[[package]]
+name = "futures-task"
+version = "0.3.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "037711b3d59c33004d3856fbdc83b99d4ff37a24768fa1be9ce3538a1cde4393"
+
+[[package]]
+name = "futures-util"
+version = "0.3.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "389ca41296e6190b48053de0321d02a77f32f8a5d2461dd38762c0593805c6d6"
+dependencies = [
+ "futures-core",
+ "futures-sink",
+ "futures-task",
+ "pin-project-lite",
+]
+
 [[package]]
 name = "generic-array"
 version = "0.14.7"
@@ -500,11 +887,22 @@ dependencies = [
  "cfg-if",
  "libc",
  "r-efi 6.0.0",
- "rand_core",
+ "rand_core 0.10.0",
  "wasip2",
  "wasip3",
 ]
 
+[[package]]
+name = "gimli"
+version = "0.32.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e629b9b98ef3dd8afe6ca2bd0f89306cec16d43d907889945bc5d6687f2f13c7"
+dependencies = [
+ "fallible-iterator",
+ "indexmap",
+ "stable_deref_trait",
+]
+
 [[package]]
 name = "git2"
 version = "0.20.4"
@@ -549,6 +947,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9229cfe53dfd69f0609a49f65461bd93001ea1ef889cd5529dd176593f5338a1"
 dependencies = [
  "foldhash",
+ "serde",
 ]
 
 [[package]]
@@ -588,7 +987,7 @@ dependencies = [
  "flatbuffers",
  "log",
  "spin",
- "thiserror",
+ "thiserror 2.0.18",
  "tracing",
  "tracing-core",
 ]
@@ -618,11 +1017,11 @@ dependencies = [
  "mshv-bindings",
  "mshv-ioctls",
  "page_size",
- "rand",
+ "rand 0.10.1",
  "rust-embed",
  "serde_json",
  "termcolor",
- "thiserror",
+ "thiserror 2.0.18",
  "tracing",
  "tracing-core",
  "tracing-log",
@@ -647,9 +1046,12 @@ dependencies = [
  "memmap2",
  "nix",
  "serde_json",
- "socket2",
+ "socket2 0.5.10",
  "tar",
+ "tempfile",
  "ureq",
+ "wasmtime",
+ "wasmtime-wasi",
  "windows-sys 0.61.2",
 ]
 
@@ -797,12 +1199,43 @@ dependencies = [
  "serde_core",
 ]
 
+[[package]]
+name = "io-extras"
+version = "0.18.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2285ddfe3054097ef4b2fe909ef8c3bcd1ea52a8f0d274416caebeef39f04a65"
+dependencies = [
+ "io-lifetimes",
+ "windows-sys 0.52.0",
+]
+
+[[package]]
+name = "io-lifetimes"
+version = "2.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "06432fb54d3be7964ecd3649233cddf80db2832f47fec34c01f65b3d9d774983"
+
+[[package]]
+name = "ipnet"
+version = "2.12.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d98f6fed1fde3f8c21bc40a1abb88dd75e67924f9cffc3ef95607bad8017f8e2"
+
 [[package]]
 name = "is_terminal_polyfill"
 version = "1.70.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a6cb138bb79a146c1bd460005623e142ef0181e3d0219cb493e02f7d08a35695"
 
+[[package]]
+name = "itertools"
+version = "0.14.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2b192c782037fadd9cfa75548310488aabdbf3d2da73885b31bd0abd03351285"
+dependencies = [
+ "either",
+]
+
 [[package]]
 name = "itoa"
 version = "1.0.17"
@@ -856,6 +1289,12 @@ version = "1.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bbd2bcb4c963f2ddae06a2efc7e9f3591312473c50c6685e1f298068316e66fe"
 
+[[package]]
+name = "leb128"
+version = "0.2.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6cc46bac87ef8093eed6f272babb833b6443374399985ac8ed28471ee0918545"
+
 [[package]]
 name = "leb128fmt"
 version = "0.1.0"
@@ -880,6 +1319,12 @@ dependencies = [
  "pkg-config",
 ]
 
+[[package]]
+name = "libm"
+version = "0.2.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b6d2cec3eae94f9f509c767b45932f1ada8350c4bdb85af2fcab4a3c14807981"
+
 [[package]]
 name = "libredox"
 version = "0.1.12"
@@ -902,6 +1347,12 @@ dependencies = [
  "vcpkg",
 ]
 
+[[package]]
+name = "linux-raw-sys"
+version = "0.4.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d26c52dbd32dccf2d10cac7725f8eae5296885fb5703b261f7d0a0739ec807ab"
+
 [[package]]
 name = "linux-raw-sys"
 version = "0.12.1"
@@ -930,22 +1381,46 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5e5032e24019045c762d3c0f28f5b6b8bbf38563a65908389bf7978758920897"
 
 [[package]]
-name = "memchr"
-version = "2.7.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f52b00d39961fc5b2736ea853c9cc86238e165017a493d1d5c8eac6bdc4cc273"
-
-[[package]]
-name = "memmap2"
-version = "0.9.9"
+name = "mach2"
+version = "0.4.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "744133e4a0e0a658e1374cf3bf8e415c4052a15a111acd372764c55b4177d490"
+checksum = "d640282b302c0bb0a2a8e0233ead9035e3bed871f0b7e81fe4a1ec829765db44"
 dependencies = [
  "libc",
 ]
 
 [[package]]
-name = "metrics"
+name = "maybe-owned"
+version = "0.3.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4facc753ae494aeb6e3c22f839b158aebd4f9270f55cd3c79906c45476c47ab4"
+
+[[package]]
+name = "memchr"
+version = "2.7.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f52b00d39961fc5b2736ea853c9cc86238e165017a493d1d5c8eac6bdc4cc273"
+
+[[package]]
+name = "memfd"
+version = "0.6.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ad38eb12aea514a0466ea40a80fd8cc83637065948eb4a426e4aa46261175227"
+dependencies = [
+ "rustix 1.1.4",
+]
+
+[[package]]
+name = "memmap2"
+version = "0.9.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "744133e4a0e0a658e1374cf3bf8e415c4052a15a111acd372764c55b4177d490"
+dependencies = [
+ "libc",
+]
+
+[[package]]
+name = "metrics"
 version = "0.24.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ff56c2e7dce6bd462e3b8919986a617027481b1dcc703175b58cf9dd98a2f071"
@@ -964,6 +1439,17 @@ dependencies = [
  "simd-adler32",
 ]
 
+[[package]]
+name = "mio"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "02bd0af71c67b473010cbbc60715ee815645a4dc942899111f494b4b737d6fda"
+dependencies = [
+ "libc",
+ "wasi",
+ "windows-sys 0.61.2",
+]
+
 [[package]]
 name = "mshv-bindings"
 version = "0.6.6"
@@ -984,7 +1470,7 @@ checksum = "77e058608d09f2f8b106b06e6c58a09aa44915dd6a36cd4142d3a7d32e59c1fb"
 dependencies = [
  "libc",
  "mshv-bindings",
- "thiserror",
+ "thiserror 2.0.18",
  "vmm-sys-util",
 ]
 
@@ -1030,6 +1516,18 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "object"
+version = "0.37.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ff76201f031d8863c38aa7f905eca4f53abbfa15f609db4277d44cd8938f33fe"
+dependencies = [
+ "crc32fast",
+ "hashbrown 0.15.5",
+ "indexmap",
+ "memchr",
+]
+
 [[package]]
 name = "once_cell"
 version = "1.21.3"
@@ -1088,6 +1586,18 @@ version = "1.13.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f89776e4d69bb58bc6993e99ffa1d11f228b839984854c7daeb5d37f87cbe950"
 
+[[package]]
+name = "postcard"
+version = "1.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6764c3b5dd454e283a30e6dfe78e9b31096d9e32036b5d1eaac7a6119ccb9a24"
+dependencies = [
+ "cobs",
+ "embedded-io 0.4.0",
+ "embedded-io 0.6.1",
+ "serde",
+]
+
 [[package]]
 name = "potential_utf"
 version = "0.1.4"
@@ -1097,6 +1607,15 @@ dependencies = [
  "zerovec",
 ]
 
+[[package]]
+name = "ppv-lite86"
+version = "0.2.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "85eae3c4ed2f50dcfe72643da4befc30deadb458a9b590d720cde2f2b1e97da9"
+dependencies = [
+ "zerocopy",
+]
+
 [[package]]
 name = "prettyplease"
 version = "0.2.37"
@@ -1116,6 +1635,29 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "pulley-interpreter"
+version = "36.0.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "329f575a931601f71fbcb3b31d32d16273da5ba7f532fc10be2e432e710b02de"
+dependencies = [
+ "cranelift-bitset",
+ "log",
+ "pulley-macros",
+ "wasmtime-internal-math",
+]
+
+[[package]]
+name = "pulley-macros"
+version = "36.0.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8bccae89ed67a40989e780105fab43e6c71a077b9fc8ae4c805ff5f73d2a79c8"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "quote"
 version = "1.0.43"
@@ -1137,6 +1679,17 @@ version = "6.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f8dcc9c7d52a811697d2151c701e0d08956f92b0e24136cf4cf27b57a6a0d9bf"
 
+[[package]]
+name = "rand"
+version = "0.8.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5ca0ecfa931c29007047d1bc58e623ab12e5590e8c7cc53200d5202b69266d8a"
+dependencies = [
+ "libc",
+ "rand_chacha",
+ "rand_core 0.6.4",
+]
+
 [[package]]
 name = "rand"
 version = "0.10.1"
@@ -1145,7 +1698,26 @@ checksum = "d2e8e8bcc7961af1fdac401278c6a831614941f6164ee3bf4ce61b7edb162207"
 dependencies = [
  "chacha20",
  "getrandom 0.4.2",
- "rand_core",
+ "rand_core 0.10.0",
+]
+
+[[package]]
+name = "rand_chacha"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
+dependencies = [
+ "ppv-lite86",
+ "rand_core 0.6.4",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
+dependencies = [
+ "getrandom 0.2.17",
 ]
 
 [[package]]
@@ -1171,7 +1743,21 @@ checksum = "a4e608c6638b9c18977b00b475ac1f28d14e84b27d8d42f70e0bf1e3dec127ac"
 dependencies = [
  "getrandom 0.2.17",
  "libredox",
- "thiserror",
+ "thiserror 2.0.18",
+]
+
+[[package]]
+name = "regalloc2"
+version = "0.12.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5216b1837de2149f8bc8e6d5f88a9326b63b8c836ed58ce4a0a29ec736a59734"
+dependencies = [
+ "allocator-api2",
+ "bumpalo",
+ "hashbrown 0.15.5",
+ "log",
+ "rustc-hash",
+ "smallvec",
 ]
 
 [[package]]
@@ -1241,6 +1827,12 @@ dependencies = [
  "walkdir",
 ]
 
+[[package]]
+name = "rustc-hash"
+version = "2.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "94300abf3f1ae2e2b8ffb7b58043de3d399c73fa6f4b73826402a5c457614dbe"
+
 [[package]]
 name = "rustc_version"
 version = "0.4.1"
@@ -1250,6 +1842,19 @@ dependencies = [
  "semver",
 ]
 
+[[package]]
+name = "rustix"
+version = "0.38.44"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fdb5bc1ae2baa591800df16c9ca78619bf65c0488b41b96ccec5d11220d8c154"
+dependencies = [
+ "bitflags 2.11.1",
+ "errno",
+ "libc",
+ "linux-raw-sys 0.4.15",
+ "windows-sys 0.52.0",
+]
+
 [[package]]
 name = "rustix"
 version = "1.1.4"
@@ -1259,10 +1864,20 @@ dependencies = [
  "bitflags 2.11.1",
  "errno",
  "libc",
- "linux-raw-sys",
+ "linux-raw-sys 0.12.1",
  "windows-sys 0.61.2",
 ]
 
+[[package]]
+name = "rustix-linux-procfs"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2fc84bf7e9aa16c4f2c758f27412dc9841341e16aa682d9c7ac308fe3ee12056"
+dependencies = [
+ "once_cell",
+ "rustix 1.1.4",
+]
+
 [[package]]
 name = "rustls"
 version = "0.23.40"
@@ -1344,6 +1959,10 @@ name = "semver"
 version = "1.0.27"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d767eb0aabc880b29956c35734170f26ed551a859dbd361d140cdbeca61ab1e2"
+dependencies = [
+ "serde",
+ "serde_core",
+]
 
 [[package]]
 name = "serde"
@@ -1352,6 +1971,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9a8e94ea7f378bd32cbbd37198a4a91436180c5bb472411e48b5ec2e2124ae9e"
 dependencies = [
  "serde_core",
+ "serde_derive",
 ]
 
 [[package]]
@@ -1424,6 +2044,9 @@ name = "smallvec"
 version = "1.15.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "67b1b7a3b5fe4f1376887184045fcf45c69e92af734b7aaddc05fb777b6fbd03"
+dependencies = [
+ "serde",
+]
 
 [[package]]
 name = "socket2"
@@ -1435,6 +2058,16 @@ dependencies = [
  "windows-sys 0.52.0",
 ]
 
+[[package]]
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+ "winx",
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+ "quote",
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+ "cap-std",
+ "cap-time-ext",
+ "fs-set-times",
+ "futures",
+ "io-extras",
+ "io-lifetimes",
+ "rustix 1.1.4",
+ "system-interface",
+ "thiserror 2.0.18",
+ "tokio",
+ "tracing",
+ "url",
+ "wasmtime",
+ "wasmtime-wasi-io",
+ "wiggle",
+ "windows-sys 0.60.2",
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+dependencies = [
+ "leb128",
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+
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@@ -1822,6 +2847,47 @@ dependencies = [
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+ "bitflags 2.11.1",
+ "thiserror 2.0.18",
+ "tracing",
+ "wasmtime",
+ "wiggle-macro",
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+
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+dependencies = [
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+ "proc-macro2",
+ "quote",
+ "syn",
+ "witx",
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+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+ "wiggle-generate",
+]
+
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+ "cranelift-assembler-x64",
+ "cranelift-codegen",
+ "gimli",
+ "regalloc2",
+ "smallvec",
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+ "thiserror 2.0.18",
+ "wasmparser 0.236.1",
+ "wasmtime-environ",
+ "wasmtime-internal-cranelift",
+ "wasmtime-internal-math",
+]
+
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@@ -1960,7 +3046,16 @@ version = "0.52.0"
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 checksum = "282be5f36a8ce781fad8c8ae18fa3f9beff57ec1b52cb3de0789201425d9a33d"
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+ "windows-targets 0.52.6",
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+dependencies = [
+ "windows-targets 0.53.5",
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- "windows_i686_msvc",
- "windows_x86_64_gnu",
- "windows_x86_64_gnullvm",
- "windows_x86_64_msvc",
+ "windows_aarch64_gnullvm 0.52.6",
+ "windows_aarch64_msvc 0.52.6",
+ "windows_i686_gnu 0.52.6",
+ "windows_i686_gnullvm 0.52.6",
+ "windows_i686_msvc 0.52.6",
+ "windows_x86_64_gnu 0.52.6",
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+ "windows_x86_64_msvc 0.52.6",
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+name = "windows_i686_gnullvm"
+version = "0.53.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fa7359d10048f68ab8b09fa71c3daccfb0e9b559aed648a8f95469c27057180c"
+
 [[package]]
 name = "windows_i686_msvc"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "240948bc05c5e7c6dabba28bf89d89ffce3e303022809e73deaefe4f6ec56c66"
 
+[[package]]
+name = "windows_i686_msvc"
+version = "0.53.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e7ac75179f18232fe9c285163565a57ef8d3c89254a30685b57d83a38d326c2"
+
 [[package]]
 name = "windows_x86_64_gnu"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "147a5c80aabfbf0c7d901cb5895d1de30ef2907eb21fbbab29ca94c5b08b1a78"
 
+[[package]]
+name = "windows_x86_64_gnu"
+version = "0.53.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c3842cdd74a865a8066ab39c8a7a473c0778a3f29370b5fd6b4b9aa7df4a499"
+
 [[package]]
 name = "windows_x86_64_gnullvm"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "24d5b23dc417412679681396f2b49f3de8c1473deb516bd34410872eff51ed0d"
 
+[[package]]
+name = "windows_x86_64_gnullvm"
+version = "0.53.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0ffa179e2d07eee8ad8f57493436566c7cc30ac536a3379fdf008f47f6bb7ae1"
+
 [[package]]
 name = "windows_x86_64_msvc"
 version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
 
+[[package]]
+name = "windows_x86_64_msvc"
+version = "0.53.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d6bbff5f0aada427a1e5a6da5f1f98158182f26556f345ac9e04d36d0ebed650"
+
+[[package]]
+name = "winx"
+version = "0.36.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3f3fd376f71958b862e7afb20cfe5a22830e1963462f3a17f49d82a6c1d1f42d"
+dependencies = [
+ "bitflags 2.11.1",
+ "windows-sys 0.52.0",
+]
+
 [[package]]
 name = "wit-bindgen"
 version = "0.51.0"
@@ -2071,7 +3241,7 @@ checksum = "ea61de684c3ea68cb082b7a88508a8b27fcc8b797d738bfc99a82facf1d752dc"
 dependencies = [
  "anyhow",
  "heck",
- "wit-parser",
+ "wit-parser 0.244.0",
 ]
 
 [[package]]
@@ -2118,10 +3288,28 @@ dependencies = [
  "serde",
  "serde_derive",
  "serde_json",
- "wasm-encoder",
+ "wasm-encoder 0.244.0",
  "wasm-metadata",
- "wasmparser",
- "wit-parser",
+ "wasmparser 0.244.0",
+ "wit-parser 0.244.0",
+]
+
+[[package]]
+name = "wit-parser"
+version = "0.236.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "16e4833a20cd6e85d6abfea0e63a399472d6f88c6262957c17f546879a80ba15"
+dependencies = [
+ "anyhow",
+ "id-arena",
+ "indexmap",
+ "log",
+ "semver",
+ "serde",
+ "serde_derive",
+ "serde_json",
+ "unicode-xid",
+ "wasmparser 0.236.1",
 ]
 
 [[package]]
@@ -2139,7 +3327,19 @@ dependencies = [
  "serde_derive",
  "serde_json",
  "unicode-xid",
- "wasmparser",
+ "wasmparser 0.244.0",
+]
+
+[[package]]
+name = "witx"
+version = "0.9.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e366f27a5cabcddb2706a78296a40b8fcc451e1a6aba2fc1d94b4a01bdaaef4b"
+dependencies = [
+ "anyhow",
+ "log",
+ "thiserror 1.0.69",
+ "wast",
 ]
 
 [[package]]
@@ -2155,7 +3355,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "32e45ad4206f6d2479085147f02bc2ef834ac85886624a23575ae137c8aa8156"
 dependencies = [
  "libc",
- "rustix",
+ "rustix 1.1.4",
 ]
 
 [[package]]
diff --git a/host/Cargo.toml b/host/Cargo.toml
index 451da06..7d065b0 100644
--- a/host/Cargo.toml
+++ b/host/Cargo.toml
@@ -26,6 +26,10 @@ path = "src/bin/pydriver_run.rs"
 name = "pyhl"
 path = "src/bin/pyhl.rs"
 
+[features]
+default = []
+wasm-host-fns = ["dep:wasmtime", "dep:wasmtime-wasi"]
+
 [dependencies]
 # danbugs/hyperlight perf/whp-warm-start — snapshot file support + WHP warm-start optimizations.
 hyperlight-host = { git = "https://github.com/danbugs/hyperlight", rev = "5cf37d92", features = ["executable_heap", "hw-interrupts", "whp-no-surrogate"] }
@@ -38,6 +42,8 @@ socket2 = { version = "0.5", features = ["all"] }
 ureq = "3"
 flate2 = "1"
 tar = "0.4"
+wasmtime = { version = "36.0.2", optional = true, default-features = false, features = ["cranelift", "runtime", "std"] }
+wasmtime-wasi = { version = "36.0.2", optional = true, default-features = false, features = ["preview1"] }
 
 [target.'cfg(unix)'.dependencies]
 nix = { version = "0.29", features = ["fs"] }
@@ -46,3 +52,5 @@ libc = "0.2"
 [target.'cfg(windows)'.dependencies]
 windows-sys = { version = "0.61", features = ["Win32_System_IO", "Win32_System_Ioctl", "Win32_Storage_FileSystem"] }
 
+[dev-dependencies]
+tempfile = "3"
diff --git a/host/src/main.rs b/host/src/main.rs
index 98f2c4e..593b17c 100644
--- a/host/src/main.rs
+++ b/host/src/main.rs
@@ -13,6 +13,9 @@ use hyperlight_unikraft::{
 };
 use std::path::PathBuf;
 
+#[cfg(feature = "wasm-host-fns")]
+mod wasm_host_fns;
+
 #[derive(Parser, Debug)]
 #[command(
     name = "hyperlight-unikraft",
@@ -39,9 +42,63 @@ struct Args {
     #[arg(long, short = 'q')]
     quiet: bool,
 
-    /// Enable tool dispatch via __dispatch host function
-    #[arg(long)]
-    enable_tools: bool,
+    #[cfg(feature = "wasm-host-fns")]
+    #[arg(
+        long = "tool",
+        value_name = "NAME=WASM",
+        help = "Register a WASIp1 module as a host tool"
+    )]
+    tool: Vec<String>,
+
+    #[cfg(feature = "wasm-host-fns")]
+    #[arg(
+        long = "tool-wasi-dir",
+        value_name = "HOST[:GUEST]",
+        help = "Preopen a read-write host directory for Wasm tools"
+    )]
+    tool_wasi_dir: Vec<String>,
+
+    #[cfg(feature = "wasm-host-fns")]
+    #[arg(
+        long = "tool-wasi-dir-ro",
+        value_name = "HOST[:GUEST]",
+        help = "Preopen a read-only host directory for Wasm tools"
+    )]
+    tool_wasi_dir_ro: Vec<String>,
+
+    #[cfg(feature = "wasm-host-fns")]
+    #[arg(
+        long = "tool-wasi-env",
+        value_name = "KEY=VALUE",
+        help = "Set an environment variable for Wasm tools"
+    )]
+    tool_wasi_env: Vec<String>,
+
+    #[cfg(feature = "wasm-host-fns")]
+    #[arg(
+        long = "tool-wasi-env-inherit",
+        value_name = "KEY",
+        help = "Inherit one host environment variable into Wasm tools"
+    )]
+    tool_wasi_env_inherit: Vec<String>,
+
+    #[cfg(feature = "wasm-host-fns")]
+    #[arg(
+        long = "tool-wasi-fuel",
+        default_value_t = 100_000_000,
+        value_name = "FUEL",
+        help = "Fuel units available to each Wasm tool call"
+    )]
+    tool_wasi_fuel: u64,
+
+    #[cfg(feature = "wasm-host-fns")]
+    #[arg(
+        long = "tool-wasi-output-limit",
+        default_value = "1Mi",
+        value_name = "SIZE",
+        help = "Maximum stdout or stderr captured from one Wasm tool call"
+    )]
+    tool_wasi_output_limit: String,
 
     /// Preopen a host directory for the guest's sandboxed filesystem.
     ///
@@ -206,6 +263,48 @@ fn main() -> Result<()> {
         None
     };
 
+    #[cfg(feature = "wasm-host-fns")]
+    let wasm_tools = {
+        if args.tool.is_empty()
+            && wasm_host_fns::WasmToolOptions::has_capabilities(
+                &args.tool_wasi_dir,
+                &args.tool_wasi_dir_ro,
+                &args.tool_wasi_env,
+                &args.tool_wasi_env_inherit,
+            )
+        {
+            return Err(anyhow::anyhow!(
+                "--tool-wasi-* flags require at least one --tool"
+            ));
+        }
+        if args.tool.is_empty() {
+            Vec::new()
+        } else {
+            let output_limit = parse_memory(&args.tool_wasi_output_limit)?;
+            let output_limit = usize::try_from(output_limit).map_err(|_| {
+                anyhow::anyhow!(
+                    "--tool-wasi-output-limit too large: {}",
+                    args.tool_wasi_output_limit
+                )
+            })?;
+            let options = wasm_host_fns::WasmToolOptions::from_cli(
+                &args.tool_wasi_dir,
+                &args.tool_wasi_dir_ro,
+                &args.tool_wasi_env,
+                &args.tool_wasi_env_inherit,
+                args.tool_wasi_fuel,
+                output_limit,
+            )?;
+            let tools = wasm_host_fns::WasmTool::load_all(&args.tool, &options)?;
+            if !args.quiet {
+                for tool in &tools {
+                    eprintln!("Tool: {} -> {}", tool.name(), tool.path().display());
+                }
+            }
+            tools
+        }
+    };
+
     let mut builder = Sandbox::builder(&args.kernel)
         .args(app_args)
         .heap_size(heap_size)
@@ -222,8 +321,11 @@ fn main() -> Result<()> {
     if let Some(ports) = listen_ports {
         builder = builder.listen_ports(ports);
     }
-    if args.enable_tools {
-        builder = builder.tool("echo", Ok);
+    #[cfg(feature = "wasm-host-fns")]
+    for tool in wasm_tools {
+        let name = tool.name().to_string();
+        let tool = std::sync::Arc::new(tool);
+        builder = builder.tool(&name, move |args| tool.invoke(args));
     }
     let mut sandbox = builder.build()?;
     let evolve_time = t0.elapsed();
diff --git a/host/src/wasm_host_fns.rs b/host/src/wasm_host_fns.rs
new file mode 100644
index 0000000..cbf920f
--- /dev/null
+++ b/host/src/wasm_host_fns.rs
@@ -0,0 +1,1124 @@
+use anyhow::{anyhow, bail, Context, Result};
+use serde_json::Value;
+use std::collections::HashSet;
+use std::path::{Path, PathBuf};
+use wasmtime::{Config, Engine, InstancePre, Linker, Module, Store};
+use wasmtime_wasi::p2::pipe::{MemoryInputPipe, MemoryOutputPipe};
+use wasmtime_wasi::preview1::{self, WasiP1Ctx};
+use wasmtime_wasi::{DirPerms, FilePerms, I32Exit, WasiCtxBuilder};
+
+#[derive(Clone)]
+pub struct WasmToolOptions {
+    dirs: Vec<WasiDir>,
+    env: Vec<(String, String)>,
+    fuel: u64,
+    output_limit: usize,
+}
+
+#[derive(Clone)]
+struct WasiDir {
+    host: PathBuf,
+    guest: String,
+    read_only: bool,
+}
+
+pub struct WasmTool {
+    name: String,
+    path: PathBuf,
+    engine: Engine,
+    pre: InstancePre<WasiP1Ctx>,
+    options: WasmToolOptions,
+}
+
+impl WasmToolOptions {
+    pub fn from_cli(
+        rw_dirs: &[String],
+        ro_dirs: &[String],
+        env: &[String],
+        inherit_env: &[String],
+        fuel: u64,
+        output_limit: usize,
+    ) -> Result<Self> {
+        if fuel == 0 {
+            bail!("--tool-wasi-fuel must be greater than 0");
+        }
+        if output_limit == 0 {
+            bail!("--tool-wasi-output-limit must be greater than 0");
+        }
+
+        let mut dirs = Vec::with_capacity(rw_dirs.len() + ro_dirs.len());
+        for spec in rw_dirs {
+            dirs.push(parse_wasi_dir(spec, false)?);
+        }
+        for spec in ro_dirs {
+            dirs.push(parse_wasi_dir(spec, true)?);
+        }
+        let mut guest_paths = HashSet::new();
+        for dir in &dirs {
+            if !guest_paths.insert(dir.guest.clone()) {
+                bail!("duplicate Wasm tool WASI guest path: {}", dir.guest);
+            }
+        }
+
+        let mut merged_env = Vec::with_capacity(env.len() + inherit_env.len());
+        for key in inherit_env {
+            if key.is_empty() {
+                bail!("--tool-wasi-env-inherit key must not be empty");
+            }
+            let value = std::env::var(key)
+                .with_context(|| format!("inherit environment variable {key}"))?;
+            set_env_pair(&mut merged_env, key.clone(), value);
+        }
+        for spec in env {
+            let (key, value) = parse_env_pair(spec)?;
+            set_env_pair(&mut merged_env, key, value);
+        }
+
+        Ok(Self {
+            dirs,
+            env: merged_env,
+            fuel,
+            output_limit,
+        })
+    }
+
+    pub fn has_capabilities(
+        rw_dirs: &[String],
+        ro_dirs: &[String],
+        env: &[String],
+        inherit_env: &[String],
+    ) -> bool {
+        !rw_dirs.is_empty() || !ro_dirs.is_empty() || !env.is_empty() || !inherit_env.is_empty()
+    }
+}
+
+impl WasmTool {
+    pub fn load_all(specs: &[String], options: &WasmToolOptions) -> Result<Vec<Self>> {
+        let mut config = Config::new();
+        config.consume_fuel(true);
+        let engine = Engine::new(&config)?;
+        let mut seen = HashSet::new();
+        let mut tools = Vec::with_capacity(specs.len());
+
+        for spec in specs {
+            let (name, path) = parse_tool_spec(spec)?;
+            if !seen.insert(name.clone()) {
+                bail!("duplicate --tool name: {name}");
+            }
+            let path = std::fs::canonicalize(&path)
+                .with_context(|| format!("canonicalize Wasm tool {}", path.display()))?;
+            let module = Module::from_file(&engine, &path)
+                .with_context(|| format!("compile Wasm tool {}", path.display()))?;
+            let mut linker: Linker<WasiP1Ctx> = Linker::new(&engine);
+            preview1::add_to_linker_sync(&mut linker, |ctx| ctx)?;
+            let pre = linker
+                .instantiate_pre(&module)
+                .with_context(|| format!("link Wasm tool {}", path.display()))?;
+            tools.push(Self {
+                name,
+                path,
+                engine: engine.clone(),
+                pre,
+                options: options.clone(),
+            });
+        }
+
+        Ok(tools)
+    }
+
+    pub fn name(&self) -> &str {
+        &self.name
+    }
+
+    pub fn path(&self) -> &Path {
+        &self.path
+    }
+
+    pub fn invoke(&self, args: Value) -> Result<Value> {
+        let request = serde_json::json!({ "name": &self.name, "args": args });
+        let stdin = serde_json::to_vec(&request)?;
+        let stdout = MemoryOutputPipe::new(self.options.output_limit);
+        let stderr = MemoryOutputPipe::new(self.options.output_limit);
+
+        let mut builder = WasiCtxBuilder::new();
+        builder
+            .allow_blocking_current_thread(true)
+            .arg(self.path.to_string_lossy())
+            .arg(&self.name)
+            .stdin(MemoryInputPipe::new(stdin))
+            .stdout(stdout.clone())
+            .stderr(stderr.clone());
+
+        for (key, value) in &self.options.env {
+            builder.env(key, value);
+        }
+        for dir in &self.options.dirs {
+            let dir_perms = if dir.read_only {
+                DirPerms::READ
+            } else {
+                DirPerms::all()
+            };
+            let file_perms = if dir.read_only {
+                FilePerms::READ
+            } else {
+                FilePerms::all()
+            };
+            builder
+                .preopened_dir(&dir.host, &dir.guest, dir_perms, file_perms)
+                .with_context(|| format!("preopen {} as {}", dir.host.display(), dir.guest))?;
+        }
+
+        let wasi = builder.build_p1();
+        let mut store = Store::new(&self.engine, wasi);
+        store.set_fuel(self.options.fuel)?;
+
+        let instance = self.pre.instantiate(&mut store)?;
+        let start = instance.get_typed_func::<(), ()>(&mut store, "_start")?;
+        let status = match start.call(&mut store, ()) {
+            Ok(()) => 0,
+            Err(err) => {
+                if let Some(exit) = err.downcast_ref::<I32Exit>() {
+                    exit.0
+                } else {
+                    let stderr_text = pipe_text(&stderr);
+                    if stderr_text.trim().is_empty() {
+                        return Err(err)
+                            .with_context(|| format!("Wasm tool {} trapped", self.name));
+                    }
+                    return Err(err).with_context(|| {
+                        format!(
+                            "Wasm tool {} trapped; stderr: {}",
+                            self.name,
+                            stderr_text.trim()
+                        )
+                    });
+                }
+            }
+        };
+
+        let stdout_bytes = stdout.contents();
+        let stdout_len = stdout_bytes.len();
+        let stdout_text = String::from_utf8_lossy(&stdout_bytes).into_owned();
+        let stderr_text = pipe_text(&stderr);
+        if status != 0 {
+            if stderr_text.trim().is_empty() {
+                bail!("Wasm tool {} exited with status {status}", self.name);
+            }
+            bail!(
+                "Wasm tool {} exited with status {status}; stderr: {}",
+                self.name,
+                stderr_text.trim()
+            );
+        }
+
+        match parse_tool_stdout(&self.name, &stdout_text) {
+            Ok(value) => Ok(value),
+            Err(err) if stdout_len >= self.options.output_limit => Err(err).with_context(|| {
+                format!(
+                    "Wasm tool {} stdout may have reached output limit of {} bytes",
+                    self.name, self.options.output_limit
+                )
+            }),
+            Err(err) => Err(err),
+        }
+    }
+}
+
+fn parse_tool_spec(spec: &str) -> Result<(String, PathBuf)> {
+    let (name, path) = spec
+        .split_once('=')
+        .ok_or_else(|| anyhow!("--tool must use NAME=WASM syntax: {spec}"))?;
+    let name = name.trim();
+    let path = path.trim();
+    if name.is_empty() {
+        bail!("--tool name must not be empty: {spec}");
+    }
+    if name.starts_with("__") || name.starts_with("fs_") || name.starts_with("net_") {
+        bail!("--tool name {name} is reserved");
+    }
+    if path.is_empty() {
+        bail!("--tool path must not be empty: {spec}");
+    }
+    Ok((name.to_string(), PathBuf::from(path)))
+}
+
+fn parse_wasi_dir(spec: &str, read_only: bool) -> Result<WasiDir> {
+    let (host, guest) = if let Some(idx) = spec.rfind(':') {
+        let (host, guest) = spec.split_at(idx);
+        let guest = &guest[1..];
+        if is_windows_drive_path(spec, idx) {
+            (spec, "/host")
+        } else if guest.starts_with('/') || guest == "." || guest.starts_with("./") {
+            (host, guest)
+        } else {
+            bail!(
+                "invalid WASI preopen guest path {:?}: expected absolute path, '.', or './path'",
+                guest
+            );
+        }
+    } else {
+        (spec, "/host")
+    };
+
+    if host.is_empty() {
+        bail!("WASI preopen host path must not be empty: {spec}");
+    }
+    if guest.is_empty() {
+        bail!("WASI preopen guest path must not be empty: {spec}");
+    }
+
+    let host = std::fs::canonicalize(host)
+        .with_context(|| format!("canonicalize WASI preopen host path {host}"))?;
+    Ok(WasiDir {
+        host,
+        guest: guest.to_string(),
+        read_only,
+    })
+}
+
+fn parse_env_pair(spec: &str) -> Result<(String, String)> {
+    let (key, value) = spec
+        .split_once('=')
+        .ok_or_else(|| anyhow!("--tool-wasi-env must use KEY=VALUE syntax: {spec}"))?;
+    if key.is_empty() {
+        bail!("--tool-wasi-env key must not be empty: {spec}");
+    }
+    Ok((key.to_string(), value.to_string()))
+}
+
+fn set_env_pair(env: &mut Vec<(String, String)>, key: String, value: String) {
+    if let Some((_, existing)) = env
+        .iter_mut()
+        .find(|(existing_key, _)| existing_key == &key)
+    {
+        *existing = value;
+    } else {
+        env.push((key, value));
+    }
+}
+
+fn is_windows_drive_path(spec: &str, colon_idx: usize) -> bool {
+    colon_idx == 1
+        && spec
+            .as_bytes()
+            .first()
+            .map(|b| b.is_ascii_alphabetic())
+            .unwrap_or(false)
+        && spec
+            .as_bytes()
+            .get(2)
+            .map(|b| *b == b'/' || *b == b'\\')
+            .unwrap_or(false)
+}
+
+fn pipe_text(pipe: &MemoryOutputPipe) -> String {
+    String::from_utf8_lossy(&pipe.contents()).into_owned()
+}
+
+fn parse_tool_stdout(name: &str, stdout: &str) -> Result<Value> {
+    let trimmed = stdout.trim();
+    if trimmed.is_empty() {
+        return Ok(Value::Null);
+    }
+
+    let value: Value = serde_json::from_str(trimmed)
+        .with_context(|| format!("Wasm tool {name} wrote non-JSON stdout"))?;
+    if let Some(object) = value.as_object() {
+        if object.len() == 1 {
+            if let Some(result) = object.get("result") {
+                return Ok(result.clone());
+            }
+            if let Some(error) = object.get("error") {
+                if let Some(message) = error.as_str() {
+                    bail!("Wasm tool {name}: {message}");
+                }
+                bail!("Wasm tool {name}: {error}");
+            }
+        }
+    }
+    Ok(value)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use serde_json::json;
+    use std::fs;
+    use tempfile::TempDir;
+
+    fn tempdir(label: &str) -> TempDir {
+        tempfile::Builder::new()
+            .prefix(&format!("hl-wasm-tools-{label}-"))
+            .tempdir()
+            .unwrap()
+    }
+
+    fn default_options() -> WasmToolOptions {
+        WasmToolOptions::from_cli(&[], &[], &[], &[], 1_000_000, 4096).unwrap()
+    }
+
+    fn options_with_limits(fuel: u64, output_limit: usize) -> WasmToolOptions {
+        WasmToolOptions::from_cli(&[], &[], &[], &[], fuel, output_limit).unwrap()
+    }
+
+    fn load_tool(name: &str, wasm: Vec<u8>, options: WasmToolOptions) -> WasmTool {
+        let dir = tempdir(name);
+        let path = dir.path().join(format!("{name}.wasm"));
+        fs::write(&path, wasm).unwrap();
+        let specs = vec![format!("{name}={}", path.display())];
+        let mut tools = WasmTool::load_all(&specs, &options).unwrap();
+        assert_eq!(tools.len(), 1);
+        tools.remove(0)
+    }
+
+    fn err_string(err: anyhow::Error) -> String {
+        format!("{err:#}")
+    }
+
+    fn encode_u32(mut value: u32, out: &mut Vec<u8>) {
+        loop {
+            let mut byte = (value & 0x7f) as u8;
+            value >>= 7;
+            if value != 0 {
+                byte |= 0x80;
+            }
+            out.push(byte);
+            if value == 0 {
+                break;
+            }
+        }
+    }
+
+    fn encode_i32(mut value: i32, out: &mut Vec<u8>) {
+        loop {
+            let byte = (value as u8) & 0x7f;
+            value >>= 7;
+            let done = (value == 0 && (byte & 0x40) == 0) || (value == -1 && (byte & 0x40) != 0);
+            if done {
+                out.push(byte);
+                break;
+            }
+            out.push(byte | 0x80);
+        }
+    }
+
+    fn encode_i64(mut value: i64, out: &mut Vec<u8>) {
+        loop {
+            let byte = (value as u8) & 0x7f;
+            value >>= 7;
+            let done = (value == 0 && (byte & 0x40) == 0) || (value == -1 && (byte & 0x40) != 0);
+            if done {
+                out.push(byte);
+                break;
+            }
+            out.push(byte | 0x80);
+        }
+    }
+
+    fn push_name(out: &mut Vec<u8>, name: &str) {
+        encode_u32(name.len() as u32, out);
+        out.extend_from_slice(name.as_bytes());
+    }
+
+    fn push_section(module: &mut Vec<u8>, id: u8, payload: Vec<u8>) {
+        module.push(id);
+        encode_u32(payload.len() as u32, module);
+        module.extend(payload);
+    }
+
+    fn func_type(params: &[u8], results: &[u8]) -> Vec<u8> {
+        let mut out = vec![0x60];
+        encode_u32(params.len() as u32, &mut out);
+        out.extend_from_slice(params);
+        encode_u32(results.len() as u32, &mut out);
+        out.extend_from_slice(results);
+        out
+    }
+
+    fn i32_const(out: &mut Vec<u8>, value: i32) {
+        out.push(0x41);
+        encode_i32(value, out);
+    }
+
+    fn i64_const(out: &mut Vec<u8>, value: i64) {
+        out.push(0x42);
+        encode_i64(value, out);
+    }
+
+    fn i32_store(out: &mut Vec<u8>) {
+        out.push(0x36);
+        encode_u32(2, out);
+        encode_u32(0, out);
+    }
+
+    fn i32_load(out: &mut Vec<u8>) {
+        out.push(0x28);
+        encode_u32(2, out);
+        encode_u32(0, out);
+    }
+
+    fn call(out: &mut Vec<u8>, index: u32) {
+        out.push(0x10);
+        encode_u32(index, out);
+    }
+
+    fn drop_value(out: &mut Vec<u8>) {
+        out.push(0x1a);
+    }
+
+    fn end(out: &mut Vec<u8>) {
+        out.push(0x0b);
+    }
+
+    fn function_body(mut instructions: Vec<u8>) -> Vec<u8> {
+        let mut body = vec![0x00];
+        if !instructions.ends_with(&[0x0b]) {
+            instructions.push(0x0b);
+        }
+        body.extend(instructions);
+        body
+    }
+
+    fn module(
+        types: Vec<Vec<u8>>,
+        imports: Vec<(&str, &str, u32)>,
+        functions: Vec<u32>,
+        export_start_index: u32,
+        memory: bool,
+        bodies: Vec<Vec<u8>>,
+        data: Vec<(u32, Vec<u8>)>,
+    ) -> Vec<u8> {
+        let mut module = vec![0x00, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00];
+
+        let mut type_payload = Vec::new();
+        encode_u32(types.len() as u32, &mut type_payload);
+        for ty in types {
+            type_payload.extend(ty);
+        }
+        push_section(&mut module, 1, type_payload);
+
+        if !imports.is_empty() {
+            let mut import_payload = Vec::new();
+            encode_u32(imports.len() as u32, &mut import_payload);
+            for (module_name, field_name, type_index) in imports {
+                push_name(&mut import_payload, module_name);
+                push_name(&mut import_payload, field_name);
+                import_payload.push(0x00);
+                encode_u32(type_index, &mut import_payload);
+            }
+            push_section(&mut module, 2, import_payload);
+        }
+
+        let mut function_payload = Vec::new();
+        encode_u32(functions.len() as u32, &mut function_payload);
+        for type_index in functions {
+            encode_u32(type_index, &mut function_payload);
+        }
+        push_section(&mut module, 3, function_payload);
+
+        if memory {
+            let memory_payload = vec![0x01, 0x00, 0x01];
+            push_section(&mut module, 5, memory_payload);
+        }
+
+        let mut export_payload = Vec::new();
+        encode_u32(if memory { 2 } else { 1 }, &mut export_payload);
+        push_name(&mut export_payload, "_start");
+        export_payload.push(0x00);
+        encode_u32(export_start_index, &mut export_payload);
+        if memory {
+            push_name(&mut export_payload, "memory");
+            export_payload.push(0x02);
+            encode_u32(0, &mut export_payload);
+        }
+        push_section(&mut module, 7, export_payload);
+
+        let mut code_payload = Vec::new();
+        encode_u32(bodies.len() as u32, &mut code_payload);
+        for body in bodies {
+            encode_u32(body.len() as u32, &mut code_payload);
+            code_payload.extend(body);
+        }
+        push_section(&mut module, 10, code_payload);
+
+        if !data.is_empty() {
+            let mut data_payload = Vec::new();
+            encode_u32(data.len() as u32, &mut data_payload);
+            for (offset, bytes) in data {
+                data_payload.push(0x00);
+                i32_const(&mut data_payload, offset as i32);
+                end(&mut data_payload);
+                encode_u32(bytes.len() as u32, &mut data_payload);
+                data_payload.extend(bytes);
+            }
+            push_section(&mut module, 11, data_payload);
+        }
+
+        module
+    }
+
+    fn stdout_module(bytes: &[u8]) -> Vec<u8> {
+        let mut instructions = Vec::new();
+        i32_const(&mut instructions, 8);
+        i32_const(&mut instructions, 64);
+        i32_store(&mut instructions);
+        i32_const(&mut instructions, 12);
+        i32_const(&mut instructions, bytes.len() as i32);
+        i32_store(&mut instructions);
+        i32_const(&mut instructions, 1);
+        i32_const(&mut instructions, 8);
+        i32_const(&mut instructions, 1);
+        i32_const(&mut instructions, 4);
+        call(&mut instructions, 0);
+        drop_value(&mut instructions);
+        end(&mut instructions);
+
+        module(
+            vec![
+                func_type(&[0x7f, 0x7f, 0x7f, 0x7f], &[0x7f]),
+                func_type(&[], &[]),
+            ],
+            vec![("wasi_snapshot_preview1", "fd_write", 0)],
+            vec![1],
+            1,
+            true,
+            vec![function_body(instructions)],
+            vec![(64, bytes.to_vec())],
+        )
+    }
+
+    fn stdin_echo_module() -> Vec<u8> {
+        let mut instructions = Vec::new();
+        i32_const(&mut instructions, 8);
+        i32_const(&mut instructions, 64);
+        i32_store(&mut instructions);
+        i32_const(&mut instructions, 12);
+        i32_const(&mut instructions, 2048);
+        i32_store(&mut instructions);
+        i32_const(&mut instructions, 0);
+        i32_const(&mut instructions, 8);
+        i32_const(&mut instructions, 1);
+        i32_const(&mut instructions, 4);
+        call(&mut instructions, 0);
+        drop_value(&mut instructions);
+        i32_const(&mut instructions, 16);
+        i32_const(&mut instructions, 64);
+        i32_store(&mut instructions);
+        i32_const(&mut instructions, 20);
+        i32_const(&mut instructions, 4);
+        i32_load(&mut instructions);
+        i32_store(&mut instructions);
+        i32_const(&mut instructions, 1);
+        i32_const(&mut instructions, 16);
+        i32_const(&mut instructions, 1);
+        i32_const(&mut instructions, 24);
+        call(&mut instructions, 1);
+        drop_value(&mut instructions);
+        end(&mut instructions);
+
+        module(
+            vec![
+                func_type(&[0x7f, 0x7f, 0x7f, 0x7f], &[0x7f]),
+                func_type(&[], &[]),
+            ],
+            vec![
+                ("wasi_snapshot_preview1", "fd_read", 0),
+                ("wasi_snapshot_preview1", "fd_write", 0),
+            ],
+            vec![1],
+            2,
+            true,
+            vec![function_body(instructions)],
+            Vec::new(),
+        )
+    }
+
+    fn env_value_module(key: &str, value_len: usize) -> Vec<u8> {
+        let mut instructions = Vec::new();
+        i32_const(&mut instructions, 32);
+        i32_const(&mut instructions, 128);
+        call(&mut instructions, 0);
+        drop_value(&mut instructions);
+        i32_const(&mut instructions, 8);
+        i32_const(&mut instructions, 128 + key.len() as i32 + 1);
+        i32_store(&mut instructions);
+        i32_const(&mut instructions, 12);
+        i32_const(&mut instructions, value_len as i32);
+        i32_store(&mut instructions);
+        i32_const(&mut instructions, 1);
+        i32_const(&mut instructions, 8);
+        i32_const(&mut instructions, 1);
+        i32_const(&mut instructions, 4);
+        call(&mut instructions, 1);
+        drop_value(&mut instructions);
+        end(&mut instructions);
+
+        module(
+            vec![
+                func_type(&[0x7f, 0x7f], &[0x7f]),
+                func_type(&[0x7f, 0x7f, 0x7f, 0x7f], &[0x7f]),
+                func_type(&[], &[]),
+            ],
+            vec![
+                ("wasi_snapshot_preview1", "environ_get", 0),
+                ("wasi_snapshot_preview1", "fd_write", 1),
+            ],
+            vec![2],
+            2,
+            true,
+            vec![function_body(instructions)],
+            Vec::new(),
+        )
+    }
+
+    fn preopen_read_file_module(path: &[u8]) -> Vec<u8> {
+        let mut instructions = Vec::new();
+        i32_const(&mut instructions, 3);
+        i32_const(&mut instructions, 0);
+        i32_const(&mut instructions, 64);
+        i32_const(&mut instructions, path.len() as i32);
+        i32_const(&mut instructions, 0);
+        i64_const(&mut instructions, 2);
+        i64_const(&mut instructions, 0);
+        i32_const(&mut instructions, 0);
+        i32_const(&mut instructions, 4);
+        call(&mut instructions, 0);
+        drop_value(&mut instructions);
+        i32_const(&mut instructions, 8);
+        i32_const(&mut instructions, 128);
+        i32_store(&mut instructions);
+        i32_const(&mut instructions, 12);
+        i32_const(&mut instructions, 512);
+        i32_store(&mut instructions);
+        i32_const(&mut instructions, 4);
+        i32_load(&mut instructions);
+        i32_const(&mut instructions, 8);
+        i32_const(&mut instructions, 1);
+        i32_const(&mut instructions, 20);
+        call(&mut instructions, 1);
+        drop_value(&mut instructions);
+        i32_const(&mut instructions, 24);
+        i32_const(&mut instructions, 128);
+        i32_store(&mut instructions);
+        i32_const(&mut instructions, 28);
+        i32_const(&mut instructions, 20);
+        i32_load(&mut instructions);
+        i32_store(&mut instructions);
+        i32_const(&mut instructions, 1);
+        i32_const(&mut instructions, 24);
+        i32_const(&mut instructions, 1);
+        i32_const(&mut instructions, 32);
+        call(&mut instructions, 2);
+        drop_value(&mut instructions);
+        end(&mut instructions);
+
+        module(
+            vec![
+                func_type(
+                    &[0x7f, 0x7f, 0x7f, 0x7f, 0x7f, 0x7e, 0x7e, 0x7f, 0x7f],
+                    &[0x7f],
+                ),
+                func_type(&[0x7f, 0x7f, 0x7f, 0x7f], &[0x7f]),
+                func_type(&[], &[]),
+            ],
+            vec![
+                ("wasi_snapshot_preview1", "path_open", 0),
+                ("wasi_snapshot_preview1", "fd_read", 1),
+                ("wasi_snapshot_preview1", "fd_write", 1),
+            ],
+            vec![2],
+            3,
+            true,
+            vec![function_body(instructions)],
+            vec![(64, path.to_vec())],
+        )
+    }
+
+    fn no_output_module() -> Vec<u8> {
+        module(
+            vec![func_type(&[], &[])],
+            Vec::new(),
+            vec![0],
+            0,
+            false,
+            vec![function_body(vec![0x0b])],
+            Vec::new(),
+        )
+    }
+
+    fn infinite_loop_module() -> Vec<u8> {
+        let instructions = vec![0x03, 0x40, 0x0c, 0x00, 0x0b, 0x0b];
+        module(
+            vec![func_type(&[], &[])],
+            Vec::new(),
+            vec![0],
+            0,
+            false,
+            vec![function_body(instructions)],
+            Vec::new(),
+        )
+    }
+
+    fn stderr_exit_module(stderr: &[u8], code: i32) -> Vec<u8> {
+        let mut instructions = Vec::new();
+        i32_const(&mut instructions, 8);
+        i32_const(&mut instructions, 64);
+        i32_store(&mut instructions);
+        i32_const(&mut instructions, 12);
+        i32_const(&mut instructions, stderr.len() as i32);
+        i32_store(&mut instructions);
+        i32_const(&mut instructions, 2);
+        i32_const(&mut instructions, 8);
+        i32_const(&mut instructions, 1);
+        i32_const(&mut instructions, 4);
+        call(&mut instructions, 0);
+        drop_value(&mut instructions);
+        i32_const(&mut instructions, code);
+        call(&mut instructions, 1);
+        end(&mut instructions);
+
+        module(
+            vec![
+                func_type(&[0x7f, 0x7f, 0x7f, 0x7f], &[0x7f]),
+                func_type(&[0x7f], &[]),
+                func_type(&[], &[]),
+            ],
+            vec![
+                ("wasi_snapshot_preview1", "fd_write", 0),
+                ("wasi_snapshot_preview1", "proc_exit", 1),
+            ],
+            vec![2],
+            2,
+            true,
+            vec![function_body(instructions)],
+            vec![(64, stderr.to_vec())],
+        )
+    }
+
+    fn unknown_import_module() -> Vec<u8> {
+        let mut instructions = Vec::new();
+        call(&mut instructions, 0);
+        end(&mut instructions);
+        module(
+            vec![func_type(&[], &[])],
+            vec![("host", "missing", 0)],
+            vec![0],
+            1,
+            false,
+            vec![function_body(instructions)],
+            Vec::new(),
+        )
+    }
+
+    #[test]
+    fn parse_tool_spec_accepts_valid_name_and_path() {
+        let (name, path) = parse_tool_spec(" greet = ./handler.wasm ").unwrap();
+        assert_eq!(name, "greet");
+        assert_eq!(path, PathBuf::from("./handler.wasm"));
+    }
+
+    #[test]
+    fn parse_tool_spec_rejects_invalid_or_reserved_names() {
+        for spec in [
+            "missing_equals",
+            "=handler.wasm",
+            "__hl_exit=handler.wasm",
+            "__dispatch=handler.wasm",
+            "fs_read=handler.wasm",
+            "net_socket=handler.wasm",
+            "greet=",
+            "greet=   ",
+        ] {
+            assert!(parse_tool_spec(spec).is_err(), "{spec} should fail");
+        }
+    }
+
+    #[test]
+    fn cli_options_parse_wasi_dirs_env_and_limits() {
+        let rw = tempdir("rw");
+        let ro = tempdir("ro");
+        let opts = WasmToolOptions::from_cli(
+            &[format!("{}:/rw", rw.path().display())],
+            &[format!("{}:/ro", ro.path().display())],
+            &["A=B".to_string(), "EMPTY=".to_string()],
+            &[],
+            123,
+            456,
+        )
+        .unwrap();
+
+        assert_eq!(opts.fuel, 123);
+        assert_eq!(opts.output_limit, 456);
+        assert_eq!(
+            opts.env,
+            vec![("A".into(), "B".into()), ("EMPTY".into(), "".into())]
+        );
+        assert_eq!(opts.dirs.len(), 2);
+        assert_eq!(opts.dirs[0].host, fs::canonicalize(rw.path()).unwrap());
+        assert_eq!(opts.dirs[0].guest, "/rw");
+        assert!(!opts.dirs[0].read_only);
+        assert_eq!(opts.dirs[1].host, fs::canonicalize(ro.path()).unwrap());
+        assert_eq!(opts.dirs[1].guest, "/ro");
+        assert!(opts.dirs[1].read_only);
+    }
+
+    #[test]
+    fn cli_options_default_wasi_guest_path_to_host() {
+        let dir = tempdir("default-guest");
+        let opts =
+            WasmToolOptions::from_cli(&[dir.path().display().to_string()], &[], &[], &[], 1, 1)
+                .unwrap();
+        assert_eq!(opts.dirs[0].guest, "/host");
+    }
+
+    #[test]
+    fn cli_options_use_last_explicit_env_value_for_duplicate_keys() {
+        let opts = WasmToolOptions::from_cli(
+            &[],
+            &[],
+            &[
+                "A=first".to_string(),
+                "B=only".to_string(),
+                "A=second".to_string(),
+            ],
+            &[],
+            1,
+            1,
+        )
+        .unwrap();
+        assert_eq!(
+            opts.env,
+            vec![("A".into(), "second".into()), ("B".into(), "only".into())]
+        );
+    }
+
+    #[test]
+    fn cli_options_reject_invalid_values() {
+        let dir = tempdir("invalid-options");
+        assert!(WasmToolOptions::from_cli(&[], &[], &[], &[], 0, 1).is_err());
+        assert!(WasmToolOptions::from_cli(&[], &[], &[], &[], 1, 0).is_err());
+        assert!(
+            WasmToolOptions::from_cli(&[], &[], &["NO_EQUALS".to_string()], &[], 1, 1).is_err()
+        );
+        assert!(WasmToolOptions::from_cli(&[], &[], &["=value".to_string()], &[], 1, 1).is_err());
+        assert!(WasmToolOptions::from_cli(&[], &[], &[], &["".to_string()], 1, 1).is_err());
+        assert!(WasmToolOptions::from_cli(
+            &[format!("{}:relative", dir.path().display())],
+            &[],
+            &[],
+            &[],
+            1,
+            1,
+        )
+        .is_err());
+        assert!(WasmToolOptions::from_cli(
+            &[
+                format!("{}:/dup", dir.path().display()),
+                format!("{}:/dup", dir.path().display())
+            ],
+            &[],
+            &[],
+            &[],
+            1,
+            1,
+        )
+        .is_err());
+    }
+
+    #[test]
+    fn has_capabilities_detects_any_wasi_capability_flag() {
+        assert!(!WasmToolOptions::has_capabilities(&[], &[], &[], &[]));
+        assert!(WasmToolOptions::has_capabilities(
+            &[".".into()],
+            &[],
+            &[],
+            &[]
+        ));
+        assert!(WasmToolOptions::has_capabilities(
+            &[],
+            &[".".into()],
+            &[],
+            &[]
+        ));
+        assert!(WasmToolOptions::has_capabilities(
+            &[],
+            &[],
+            &["A=B".into()],
+            &[]
+        ));
+        assert!(WasmToolOptions::has_capabilities(
+            &[],
+            &[],
+            &[],
+            &["PATH".into()]
+        ));
+    }
+
+    #[test]
+    fn parse_tool_stdout_handles_raw_values_and_envelopes() {
+        assert_eq!(parse_tool_stdout("t", "").unwrap(), Value::Null);
+        assert_eq!(parse_tool_stdout("t", "  \n ").unwrap(), Value::Null);
+        assert_eq!(parse_tool_stdout("t", "42").unwrap(), json!(42));
+        assert_eq!(
+            parse_tool_stdout("t", "{\"result\":{\"ok\":true}}").unwrap(),
+            json!({"ok": true})
+        );
+        assert_eq!(
+            parse_tool_stdout("t", "{\"result\":1,\"extra\":2}").unwrap(),
+            json!({"result": 1, "extra": 2})
+        );
+        assert!(
+            err_string(parse_tool_stdout("t", "{\"error\":\"boom\"}").unwrap_err())
+                .contains("Wasm tool t: boom")
+        );
+        assert!(err_string(parse_tool_stdout("t", "not json").unwrap_err())
+            .contains("wrote non-JSON stdout"));
+    }
+
+    #[test]
+    fn load_all_rejects_duplicate_names_invalid_wasm_and_unknown_imports() {
+        let dir = tempdir("load-errors");
+        let ok = dir.path().join("ok.wasm");
+        let bad = dir.path().join("bad.wasm");
+        let unknown = dir.path().join("unknown.wasm");
+        fs::write(&ok, no_output_module()).unwrap();
+        fs::write(&bad, b"not wasm").unwrap();
+        fs::write(&unknown, unknown_import_module()).unwrap();
+        let options = default_options();
+
+        let duplicate_err = WasmTool::load_all(
+            &[format!("a={}", ok.display()), format!("a={}", ok.display())],
+            &options,
+        )
+        .err()
+        .expect("duplicate tool name should fail");
+        assert!(err_string(duplicate_err).contains("duplicate --tool name"));
+
+        let invalid_err = WasmTool::load_all(&[format!("bad={}", bad.display())], &options)
+            .err()
+            .expect("invalid wasm should fail");
+        assert!(err_string(invalid_err).contains("compile Wasm tool"));
+
+        let link_err = WasmTool::load_all(&[format!("unknown={}", unknown.display())], &options)
+            .err()
+            .expect("unknown import should fail");
+        assert!(err_string(link_err).contains("link Wasm tool"));
+    }
+
+    #[test]
+    fn invoke_passes_dispatch_request_on_stdin() {
+        let tool = load_tool("echo_req", stdin_echo_module(), default_options());
+        let result = tool.invoke(json!({"n": 7, "s": "hello"})).unwrap();
+        assert_eq!(result["name"], "echo_req");
+        assert_eq!(result["args"], json!({"n": 7, "s": "hello"}));
+    }
+
+    #[test]
+    fn invoke_passes_configured_environment() {
+        let key = "HL_WASM_JSON";
+        let value = r#"{"result":"env-ok"}"#;
+        let options =
+            WasmToolOptions::from_cli(&[], &[], &[format!("{key}={value}")], &[], 1_000_000, 4096)
+                .unwrap();
+        let tool = load_tool("env", env_value_module(key, value.len()), options);
+        let result = tool.invoke(json!({})).unwrap();
+        assert_eq!(result, json!("env-ok"));
+    }
+
+    #[test]
+    fn invoke_can_read_explicit_read_only_preopen() {
+        let root = tempdir("preopen-read");
+        fs::write(root.path().join("answer.json"), br#"{"result":"file-ok"}"#).unwrap();
+        let options = WasmToolOptions::from_cli(
+            &[],
+            &[format!("{}:.", root.path().display())],
+            &[],
+            &[],
+            1_000_000,
+            4096,
+        )
+        .unwrap();
+        let tool = load_tool(
+            "read_preopen",
+            preopen_read_file_module(b"answer.json"),
+            options,
+        );
+        let result = tool.invoke(json!({})).unwrap();
+        assert_eq!(result, json!("file-ok"));
+    }
+
+    #[test]
+    fn invoke_unwraps_result_envelope() {
+        let tool = load_tool(
+            "answer",
+            stdout_module(br#"{"result":{"ok":true,"answer":42}}"#),
+            default_options(),
+        );
+        let result = tool.invoke(json!({"ignored": true})).unwrap();
+        assert_eq!(result, json!({"ok": true, "answer": 42}));
+    }
+
+    #[test]
+    fn invoke_returns_null_for_empty_stdout() {
+        let tool = load_tool("empty", no_output_module(), default_options());
+        let result = tool.invoke(json!({})).unwrap();
+        assert_eq!(result, Value::Null);
+    }
+
+    #[test]
+    fn invoke_converts_error_envelope_to_handler_error() {
+        let tool = load_tool(
+            "fail",
+            stdout_module(br#"{"error":"boom"}"#),
+            default_options(),
+        );
+        let err = tool.invoke(json!({})).unwrap_err();
+        assert!(err_string(err).contains("Wasm tool fail: boom"));
+    }
+
+    #[test]
+    fn invoke_reports_nonzero_exit_status() {
+        let tool = load_tool("exit_only", stderr_exit_module(b"", 9), default_options());
+        let err = tool.invoke(json!({})).unwrap_err();
+        assert!(err_string(err).contains("exited with status 9"));
+    }
+
+    #[test]
+    fn invoke_includes_stderr_for_nonzero_exit() {
+        let tool = load_tool(
+            "stderr_exit",
+            stderr_exit_module(b"details from stderr", 7),
+            default_options(),
+        );
+        let err = tool.invoke(json!({})).unwrap_err();
+        let msg = err_string(err);
+        assert!(msg.contains("exited with status 7"));
+        assert!(msg.contains("details from stderr"));
+    }
+
+    #[test]
+    fn invoke_traps_when_stdout_exceeds_limit() {
+        let tool = load_tool(
+            "too_much",
+            stdout_module(br#"{"result":"this is too long"}"#),
+            options_with_limits(1_000_000, 8),
+        );
+        let err = tool.invoke(json!({})).unwrap_err();
+        let msg = err_string(err);
+        assert!(msg.contains("stdout may have reached output limit of 8 bytes"));
+        assert!(msg.contains("wrote non-JSON stdout"));
+    }
+
+    #[test]
+    fn invoke_traps_when_fuel_is_exhausted() {
+        let tool = load_tool(
+            "spin",
+            infinite_loop_module(),
+            options_with_limits(10, 1024),
+        );
+        let err = tool.invoke(json!({})).unwrap_err();
+        let msg = err_string(err);
+        assert!(msg.contains("Wasm tool spin trapped"));
+        assert!(msg.contains("fuel"));
+    }
+}