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Version: 0.1.0-alpha.4 (alpha)

C# compiler and runtime profile

For application development, use Creating a capsule. That shared tutorial has all six language choices and uses dev init, build, deploy and test. You do not need the source-build commands below for it.

This reference is for compiler integration, custom package signing and direct node admission. The complete source recipe is retained here for developers who need to work below the packaged workflow.

Create an independent C# project, edit its typed contract, and run its signed package on a local node. Your application lives outside the LSF checkout.

Use Linux x86-64, Python 3.13.5, Rust 1.97.1 and .NET SDK 10.0.100. The captured compiler uses Componentize.NET 0.8.0-preview00011 and its exact NativeAOT LLVM dependency lock. This experimental profile is not a general .NET host: no JIT, dynamic assemblies, application packages, thread pool, timers or host event loop. Contract calls suspend through the LSF runtime. Run from the checkout after installing the pinned .NET and Rust SDKs:

DOTNET_COMPILERS=$(mktemp -d "${TMPDIR:-/tmp}/lsf-dotnet-tools.XXXXXXXX")
curl --fail --location --max-time 180 \
  https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-29/wasi-sdk-29.0-x86_64-linux.tar.gz \
  --output "$DOTNET_COMPILERS/wasi-sdk.tar.gz"
printf '%s  %s\n' 87d1d1a2879d139cdc624b968efad3d4a97b8078cdff95e63ac88ecafd1a0171 "$DOTNET_COMPILERS/wasi-sdk.tar.gz" | sha256sum --check --strict
tar -xzf "$DOTNET_COMPILERS/wasi-sdk.tar.gz" -C "$DOTNET_COMPILERS"
cargo install --locked wasm-tools --version 1.254.0
python3 tools/install_guest_bindgen.py "$DOTNET_COMPILERS/bindgen"
export PATH="$DOTNET_COMPILERS/bindgen:$PATH"
rustup target add wasm32-unknown-unknown --toolchain 1.97.1
python3 tools/dotnet_capsule.py install-tools "$DOTNET_COMPILERS/dotnet" \
  --wasi-sdk "$DOTNET_COMPILERS/wasi-sdk-29.0-x86_64-linux"
export LSF_DOTNET_TOOLS="$DOTNET_COMPILERS/dotnet"
cargo --config .cargo/managed-guest.toml build --locked -p latent -p latentd --bins \
  -p latent-packaging --example package --example capsule_contracts \
  -p latent-policy --example capsule_authoring

Keep these exact compiler executables on PATH. Run the following six Bash blocks in one terminal.

1. Create a project​

set -euo pipefail
umask 077
LSF_CHECKOUT=$PWD
BIN="${CARGO_TARGET_DIR:-$PWD/target}/debug"
export LSF_DOTNET_PROJECTS="${LSF_DOTNET_PROJECTS:-$(mktemp -d "${TMPDIR:-/tmp}/lsf-dotnet-projects.XXXXXXXX")}"
python3 tools/dotnet_capsule.py new "$LSF_DOTNET_PROJECTS/my-greeting" --template greeting

Open my-greeting/src/Main.cs and my-greeting/wit/world.wit. They contain the complete greeting example, including its ordinary C# implementation of the generated typed export. The contract is:

greet: func(name: string) -> result<string, string>;

The project includes authoritative WIT, capsule-project.json, pinned Capsule.csproj/global.json, and an immutable SDK in vendor/lsf. Edit src/*.cs and wit, using the generated export namespace/class for your selected service world. Keep SDK/compiler configuration unchanged. The builder rejects SDK drift, escaping paths, unreviewed MSBuild inputs and application NuGet dependencies. Generated C# and typed Lsf.Guest capability facades are compiled from the actual selected WIT, not handwritten ABI guesses.

The word-count and shipping templates provide equivalent C# implementations of Creating a capsule. Choose another project directory and replace greeting in the creation command with either template name. http-status adds a typed, asynchronous HTTP call; its import still needs an installed provider and an explicit deployment grant. Creating a project grants no network access.

2. Build and package the project​

python3 tools/dotnet_capsule.py build "$LSF_DOTNET_PROJECTS/my-greeting" \
  --tools "$LSF_DOTNET_TOOLS" \
  --output "$LSF_DOTNET_PROJECTS/greeting-build" \
  --contracts-tool "$BIN/examples/capsule_contracts" \
  --packager "$BIN/examples/package" \
  --repository https://github.com/KirilsTurkins/latent-service-fabric

Use your own public repository URL for an application you maintain. That label does not authenticate its source. The builder captures the actual project files, checks generated SDK bindings, builds the component, derives contracts from WIT, and inspects the package. BUILD-COMPLETE.json appears only after all steps succeed. Use a fresh output directory for each new attempt.

The output includes component.wasm, capsule.json, contracts.json, wit-lock.json, deployment.json, package/ and build-observation.json. Full-width WIT integers retain their original types; application errors remain result values. Unsupported WIT types fail explicitly during contract derivation.

3. Sign for this local experiment​

The following signer creates short-lived publisher and builder keys in memory, signs this exact build, and writes a policy for a new isolated node. It also adds an inventory of the package's component and WIT inputs. It does not assert a complete transitive dependency inventory. The keys never enter the compiler.

"$BIN/examples/capsule_authoring" demo-sign "$LSF_DOTNET_PROJECTS/releases" \
  "$LSF_DOTNET_PROJECTS/greeting-build"

This policy lasts for this experiment and accepts only the captured source and builder recipe. For a maintained deployment, use your organization's publisher, builder and revocation policies through the package workflow. Finish the steps below within 30 minutes of signing; otherwise sign into a new directory and start a new experiment. Only this isolated demo gives publisher and builder proofs the same finite 1,800-second window as its signatures. Signature expiry, revocation and the node's currentness checks remain enforced; production policies are unchanged.

4. Start a node with enforced admission​

This node listens on an automatically selected loopback port. Its random client credential stays in private files. It verifies both package signatures and the builder policy before admitting a release.

Download this step's script, then run it in the same terminal. You can expand the script to inspect the commands first.

View the setup script
mkdir "$LSF_DOTNET_PROJECTS/node" "$LSF_DOTNET_PROJECTS/results"
python3 - <<'PY'
import json, os, secrets, shutil
from pathlib import Path
root = Path(os.environ["LSF_DOTNET_PROJECTS"])
shutil.copyfile(root / "releases/policy.json", root / "node/policy.json")
token = secrets.token_urlsafe(32)
node = {
    "formatVersion": 1, "nodeId": "dotnet-learning-node", "dataDirectory": "data",
    "bind": "127.0.0.1:0", "securityProfile": "local-experimental-v1",
    "supplyChain": {"mode": "enforced", "policyFile": "policy.json", "clockLeaseSeconds": 5},
    "workers": {"runtime": 1, "control": 1},
    "cells": [{"class": "standard", "capacity": 1, "queueCapacity": 2, "maximumMemoryBytes": 134217728}],
    "execution": {"maximumCpuFuel": 1000000000, "maximumWallTimeMillis": 120000},
    "cache": {"entries": 2, "preparations": 1},
    "budgetProfile": {"mode": "phase3", "maximumOutboundRequests": 0,
                      "maximumBlobReadBytes": 0, "maximumBlobWriteBytes": 0},
    "capabilityPolicies": {"formatVersion": 1, "maximumControlJobs": 2},
    "audit": {"mode": "durable", "records": 1024, "diskBytes": 16777216,
              "queuedOperations": 8, "queryOwners": 2},
    "credentials": [{"token": token, "subject": "dotnet-learner", "tenant": "examples", "role": "operator"}],
}
runtime_imports = {
    "clockMonotonic": "latent:clock/monotonic@0.1.0",
}
node["providers"] = {"formatVersion": 1, "bindings": []}
for name, contract in runtime_imports.items():
    node["providers"][name] = {"identity": {
        "id": name, "tenant": "examples", "service": "runtime-host", "epoch": 1}}
    node["providers"]["bindings"].append({
        "name": name, "tenant": "examples", "consumerService": "examples/my-greeting",
        "providerService": "runtime-host", "contract": contract, "providerBinding": name + "-installed"})
with (root / "node/node.json").open("x") as output:
    json.dump(node, output)
PY
"$BIN/latentd" check-config --config "$LSF_DOTNET_PROJECTS/node/node.json"
"$BIN/latentd" serve --config "$LSF_DOTNET_PROJECTS/node/node.json" \
  >"$LSF_DOTNET_PROJECTS/node/status.jsonl" 2>"$LSF_DOTNET_PROJECTS/node/diagnostics.jsonl" &
DOTNET_NODE_PID=$!
stop_dotnet_node() {
    if [[ -n "$DOTNET_NODE_PID" ]]; then
        local pid=$DOTNET_NODE_PID result=0
        DOTNET_NODE_PID=
        kill -TERM "$pid" 2>/dev/null || true
        for ((attempt=0; attempt<100; attempt++)); do
            if ! kill -0 "$pid" 2>/dev/null; then break; fi
            sleep 0.05
        done
        if kill -0 "$pid" 2>/dev/null; then kill -KILL "$pid" 2>/dev/null || true; result=1; fi
        wait "$pid" || result=1
        return "$result"
    fi
}
trap 'stop_dotnet_node >/dev/null 2>&1 || true' EXIT
trap 'exit 130' INT
trap 'exit 143' TERM
python3 - <<'PY'
import json, os, time
from pathlib import Path
root = Path(os.environ["LSF_DOTNET_PROJECTS"])
deadline = time.monotonic() + 30
while True:
    lines = (root / "node/status.jsonl").read_text().splitlines()
    if lines:
        endpoint = json.loads(lines[0])["endpoint"]
        break
    if time.monotonic() >= deadline:
        raise SystemExit("Node did not start; inspect node/diagnostics.jsonl")
    time.sleep(0.05)
token = json.loads((root / "node/node.json").read_text())["credentials"][0]["token"]
client = {"formatVersion": 1, "defaultProfile": "local", "profiles": [{
    "name": "local", "endpoint": "http://" + endpoint, "tenant": "examples", "token": token,
    "connectTimeoutMillis": 1000, "rpcTimeoutMillis": 125000,
}]}
with (root / "client.json").open("x") as output:
    json.dump(client, output)
PY
dotnet_cli() { "$BIN/latent" --config "$LSF_DOTNET_PROJECTS/client.json" --output json "$@"; }
dotnet_cli node get dotnet-learning-node >"$LSF_DOTNET_PROJECTS/results/node.json"

Run source "$HOME/Downloads/dotnet-authoring-1.sh".

5. Publish, deploy and invoke​

Publishing returns an exact publication identity. This C# runtime needs explicit monotonic-clock authority for the GC even for a greeting; no wall-clock or entropy is implicitly granted. The next block scopes each grant to this one publication, service, operation and caller. There is no ambient WASI authority. Omitting a grant produces a platform denial before the application can return. The guest's 128 MiB memory and fuel budgets bound its runtime heap; no guest can create a host thread.

Download this step's script, then run it in the same terminal. You can expand the script to inspect the commands first.

View the setup script
dotnet_cli release publish-package "$LSF_DOTNET_PROJECTS/releases/my-greeting/package" \
  --evidence "$LSF_DOTNET_PROJECTS/releases/my-greeting/evidence/index.json" \
  --operation-id publish-my-greeting --expected-generation 0 \
  >"$LSF_DOTNET_PROJECTS/results/published.json"
python3 - <<'PY'
import json, os
from pathlib import Path
root = Path(os.environ["LSF_DOTNET_PROJECTS"])
deployment = json.loads((root / "releases/my-greeting/deployment.json").read_text())
published = json.loads((root / "results/published.json").read_text())
publication = published["data"]["operation"]["publication"]["id"]
deployment["spec"]["publication"] = publication
deployment["spec"]["grants"] = []
startup = json.loads((root / "node/status.jsonl").read_text().splitlines()[0])
for provider in startup["providers"]:
    name, capability = provider["id"], provider["capability"]
    operation, kind = {
        "clockMonotonic": ("now-nanos", "clock"),
    }[name]
    binding = {"formatVersion": 1, "tenant": "examples", "capability": capability,
        "providerProfile": provider["profile"], "configurationDigest": provider["configurationDigest"],
        "configurationEpoch": int(provider["configurationEpoch"]), "restriction": {"operations": [operation]}}
    policy = {"formatVersion": 1, "tenant": "examples", "rules": [{
        "id": "runtime", "effect": "allow", "principals": [{"kind": "administrator", "subject": "dotnet-learner"}],
        "services": ["examples/my-greeting"], "publications": [publication], "capability": capability,
        "operations": [operation], "resources": {"kind": kind},
        "ceiling": {"operations": 4096, "inputBytes": 8 if kind == "random" else 0, "outputBytes": 32768, "wallTimeMillis": 5000}}]}
    for suffix, document in (("binding", binding), ("policy", policy)):
        with (root / "results" / (name + "-" + suffix + ".json")).open("x") as output:
            json.dump(document, output)
    deployment["spec"]["grants"].append({"capability": capability, "policy": name + "-allow"})
with (root / "results/deployment.json").open("x") as output:
    json.dump(deployment, output)
PY
for name in clockMonotonic; do
    dotnet_cli policy --kind provider-binding apply --id "$name-installed" \
      --file "$LSF_DOTNET_PROJECTS/results/$name-binding.json" \
      --operation-id "install-$name" --expected-generation 0
    dotnet_cli policy apply --id "$name-allow" --file "$LSF_DOTNET_PROJECTS/results/$name-policy.json" \
      --operation-id "grant-$name" --expected-generation 0
done
dotnet_cli deployment apply "$LSF_DOTNET_PROJECTS/results/deployment.json" --expected-generation 0 \
  >"$LSF_DOTNET_PROJECTS/results/deployed.json"
printf '["Ada"]\n' >"$LSF_DOTNET_PROJECTS/results/input.json"
dotnet_cli invoke --memory-bytes 134217728 --cpu-fuel 1000000000 --wall-time-ms 120000 \
  --service examples/my-greeting --route my-greeting \
  --contract examples:greeting/api@1.0.0 --function greet --activation-id my-greeting-valid \
  --input "$LSF_DOTNET_PROJECTS/results/input.json" >"$LSF_DOTNET_PROJECTS/results/answer.json"
dotnet_answer() {
    python3 - "$1" <<'PY'
import base64, json, sys
data = json.load(open(sys.argv[1]))["data"]
payload = data.get("payload") or data["declaredError"]["payload"]
print(base64.b64decode(payload["data"]).decode())
PY
}
dotnet_answer "$LSF_DOTNET_PROJECTS/results/answer.json"
printf '[""]\n' >"$LSF_DOTNET_PROJECTS/results/empty.json"
dotnet_cli invoke --memory-bytes 134217728 --cpu-fuel 1000000000 --wall-time-ms 120000 \
  --service examples/my-greeting --route my-greeting \
  --contract examples:greeting/api@1.0.0 --function greet --activation-id my-greeting-invalid \
  --input "$LSF_DOTNET_PROJECTS/results/empty.json" >"$LSF_DOTNET_PROJECTS/results/error.json" || test "$?" -eq 3
dotnet_answer "$LSF_DOTNET_PROJECTS/results/error.json"

Run source "$HOME/Downloads/dotnet-authoring-2.sh".

Expected answers are [{"ok":"Hello, Ada!"}] and [{"err":"Please enter a name."}]. Exit code 3 is a declared application error. Connection failures, exhausted budgets and guest traps have different outcomes. Use a new activation ID for a new request; an uncertain mutation must be inspected before any retry.

6. Clean up and continue​

Wait for the completed calls' bounded audit work to drain before deleting the deployment once. This helper performs only read-only capability inspections, with a five-second observation deadline and at most 32 reads, and records the observed audit ownership counters, including queued and staging bytes. Missing audit counters, unavailable observations, a closed/recovering journal, or an expired deadline stop cleanup; inspect that failure instead of retrying an uncertain deletion. Each inspection has a one-second process bound plus at most five seconds for owned child cleanup. The idle snapshot is not a reservation or a guarantee of retained-disk capacity; concurrent work can still consume capacity. The single deletion still checks its current policy, generation and capacity.

python3 tools/wait_capsule_audit_idle.py --cli "$BIN/latent" \
  --config "$LSF_DOTNET_PROJECTS/client.json" --deployment my-greeting \
  >"$LSF_DOTNET_PROJECTS/results/audit-idle.json"
GENERATION=$(python3 -c 'import json,os; print(json.load(open(os.environ["LSF_DOTNET_PROJECTS"]+"/results/deployed.json"))["data"]["deployment"]["generation"])')
dotnet_cli deployment delete my-greeting --expected-generation "$GENERATION"
stop_dotnet_node
printf 'Saved project and results: %s\n' "$LSF_DOTNET_PROJECTS"

Your source and results remain at that path. Edit the greeting, create a new build directory, and repeat signing and delivery to try a change. The delivery and recovery guide explains update and recovery principles using its separate Rust tutorial project and node. Its commands require that tutorial's prerequisites and variables; for this C# project, retain the build, signing and admission path above.

For capabilities, use the guest SDK reference. It covers buffered and streaming HTTP, blobs, secrets, events, local calls, randomness and metrics, including each wrapper's close/drop rules. The C# guest SDK supplies typed Lsf.Guest facades over exact generated interfaces. Use consuming operations and using/Dispose for owners; there is no finalizer-driven resource release. Aliases share a single consumed/borrowed state. An imported effect is allowed only by host policy. Pending calls retain their budget until the host releases them; cancelling a subtask never proves an external effect did not occur.

If a build fails, inspect BUILD-FAILED.json and logs/ in that attempt's output. SDK binding drift means the SDK and generator pins disagree; do not edit the lock to bypass it. A denied publication commonly means the policy expired, the exact source approval differs, or an evidence file is missing. A denied HTTP call requires checking the deployment grant, provider binding and allowed destination.