feat(decider): compile deciders to WASM/WIT components

.github/actions/setup-rust/action.yml

@@ -18,6 +18,15 @@ runs:
         rustup component add rustfmt clippy llvm-tools-preview \
           --toolchain "${RUSTUP_TOOLCHAIN:-$(rustup show active-toolchain | awk '{print $1}')}"
 
+    # Added serially here rather than through rust-toolchain.toml `targets`: that field makes
+    # every concurrent `cargo install` during `mise install` trigger its own rustup target
+    # download, and the parallel downloads corrupt each other (rename fails with os error 2).
+    - name: Install wasm32 target
+      shell: bash
+      run: |
+        rustup target add wasm32-unknown-unknown \
+          --toolchain "${RUSTUP_TOOLCHAIN:-$(rustup show active-toolchain | awk '{print $1}')}"
+
     - name: Install Dylint Rust components
       shell: bash
       run: |

.github/workflows/ci-rust.yml

@@ -22,6 +22,9 @@ concurrency:
 
 env:
   CARGO_TERM_COLOR: always
+  # Source-built mise tools (dylint-link, cargo-component, ...) fetch crates from
+  # crates.io during install; raise retry tolerance for spurious network errors.
+  CARGO_NET_RETRY: '10'
 
 permissions:
   contents: read
@@ -107,6 +110,10 @@ jobs:
         with:
           tool: cargo-llvm-cov,nextest
 
+      - name: Build decider components for sim fixtures
+        run: cargo component build -p trogon-schedules-decider --target wasm32-unknown-unknown --release
+        working-directory: rsworkspace
+
       - name: Run documentation tests
         run: cargo test --doc
         working-directory: rsworkspace
@@ -156,3 +163,45 @@ jobs:
       - name: Build release
         run: cargo build --release
         working-directory: rsworkspace
+
+  wasm-decider:
+    runs-on: ubuntu-latest
+    permissions:
+      actions: write
+      contents: read
+    steps:
+      - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
+        with:
+          persist-credentials: false
+
+      - name: Setup Rust
+        uses: ./.github/actions/setup-rust
+
+      - name: Cache dependencies
+        uses: Swatinem/rust-cache@c19371144df3bb44fab255c43d04cbc2ab54d1c4 # v2.9.1
+        with:
+          workspaces: rsworkspace -> target
+          save-if: always
+
+      - name: Build schedules decider component
+        run: cargo component build -p trogon-schedules-decider --target wasm32-unknown-unknown --release
+        working-directory: rsworkspace
+
+      - name: Assert zero imports and validate
+        run: |
+          for WASM in rsworkspace/target/wasm32-unknown-unknown/release/trogon_schedules_decider.wasm; do
+            wasm-tools component wit "$WASM" | tee /tmp/wit.txt
+            if grep -E '^[[:space:]]*import ' /tmp/wit.txt; then
+              echo "component declares imports: $WASM"
+              exit 1
+            fi
+            wasm-tools validate "$WASM"
+          done
+
+      - name: Run decider-test suites
+        run: |
+          cd rsworkspace
+          cargo test -p trogon-decider-sim --test schedules --features test-support
+          cargo test -p trogon-decider-guest-macros --test compile_fail
+          cargo build -p trogon-decider-test --release
+          ./target/release/decider-test target/wasm32-unknown-unknown/release/trogon_schedules_decider.wasm cli/trogon-decider-test/schedules.yaml

.mise.toml

@@ -5,6 +5,8 @@ buf = "1.70.0"
 "cargo:dylint-link" = "6.0.1"
 "cargo:protoc-gen-buffa" = "0.7.0"
 "cargo:protoc-gen-buffa-packaging" = "0.7.0"
+"cargo:cargo-component" = "0.21.1"
+"cargo:wasm-tools" = "1.250.0"
 node = "26.3.0"
 pnpm = "11.5.1"
 python = "3.14.5"
@@ -45,6 +47,24 @@ description = "Format generated Rust protobuf bindings"
 dir = "rsworkspace"
 run = "cargo fmt --all"
 
+[tasks."proto:schedules-descriptor-set"]
+description = "Generate FileDescriptorSet for the schedules decider test runner"
+run = "mkdir -p rsworkspace/target/wasm32-unknown-unknown/release && buf build -o rsworkspace/target/wasm32-unknown-unknown/release/trogon_schedules_decider.binpb --as-file-descriptor-set --path proto/trogonai/scheduler/schedules"
+
+[tasks."rust:wasm-target"]
+description = "Ensure the wasm32-unknown-unknown Rust target is installed"
+run = "rustup target add wasm32-unknown-unknown"
+
+[tasks."artifacts:schedules-wasm"]
+description = "Build schedules decider WASM artifact to dist/decider/"
+depends = ["proto:schedules-descriptor-set", "rust:wasm-target"]
+run = "cd rsworkspace && cargo component build -p trogon-schedules-decider --target wasm32-unknown-unknown --release && mkdir -p dist/decider && cp target/wasm32-unknown-unknown/release/trogon_schedules_decider.wasm dist/decider/schedules.wasm && cp target/wasm32-unknown-unknown/release/trogon_schedules_decider.binpb dist/decider/schedules.binpb"
+
+[tasks."artifacts:decider-test"]
+description = "Build schedules decider WASM + decider-test CLI"
+depends = ["artifacts:schedules-wasm"]
+run = "cd rsworkspace && cargo build -p trogon-decider-test --release"
+
 [tasks."rsc"]
 description = "Format and check all Rust code (fmt, clippy, all targets, all features)"
 dir = "rsworkspace"

WASM_TODO.md

@@ -0,0 +1,37 @@
+# WASM Decider — Remaining Work
+
+Goal: deciders compile to WASM components (WIT-defined interface) so they can be
+deployed/distributed independently of the host runtime.
+
+v1 (M0 spike + M1 YAML test runner + scheduler WASM bundle) is **complete and merged**.
+Design discovery, decisions, benchmarks, and the v1 implementation log have been removed —
+they live in git history. What follows is only the work that has **not** been done.
+
+## Deferred past v1 (P2)
+
+- [ ] **Typed cross-language codec + proto→WIT emitter.** Publish a per-stream-type codec
+      library component (`encode`/`decode` of version-faithful typed events) with WIT types
+      generated from the same proto source (Nth codegen target beside Rust/Elixir). Must map
+      proto open enums → WIT closed variant with an explicit `unknown` case; handle field
+      presence, maps, well-known types, recursion. v1 cross-language consumers decode bytes
+      with their own native proto library instead.
+- [ ] **Platform service.** Host service embedding wasmtime: NATS command subjects in,
+      JetStream persistence (replay/OCC/snapshots host-owned), components pulled from a
+      registry. Untrusted-ready: fuel/epoch limits, memory caps, per-execution timeouts,
+      instance isolation.
+- [ ] **Registry / OCI distribution.** PR → CI builds artifact → registry → platform pulls
+      by digest (digest pinning from the start; signing/provenance later).
+- [ ] **Browser jco host.** jco-transpiled components running in-browser for unit testing
+      and AI-sandbox simulation; reuse the in-memory sim host contract.
+- [ ] **`Decision::Act` support.** Currently v1 is events-only (scheduler never uses `Act`).
+      If needed, extend `decide`'s return with a variant for host-driven iteration — additive,
+      does not break events-only modules.
+- [ ] **StateModel / Command split (optional refactor).** Split the fused `Decider` trait
+      into `StateModel` (State/Event/initial_state/evolve) + `Command` (decide), so bundle
+      state-agreement becomes a type fact instead of macro-emitted bounds.
+
+## Ideas (unscheduled)
+
+- [ ] Expose the sim host as an MCP tool (via mcp-nats) so agents can load/test/simulate
+      deciders over the wire.
+- [ ] Conformance gate at registry upload: run the YAML given/when/then suites on push.

proto/trogonai/scheduler/schedules/v1/create_schedule.proto

@@ -0,0 +1,17 @@
+edition = "2024";
+
+package trogonai.scheduler.schedules.v1;
+
+import "trogonai/scheduler/schedules/v1/delivery.proto";
+import "trogonai/scheduler/schedules/v1/message.proto";
+import "trogonai/scheduler/schedules/v1/schedule.proto";
+import "trogonai/scheduler/schedules/v1/schedule_status.proto";
+
+// Wire command to create a schedule stream.
+message CreateSchedule {
+  string schedule_id = 1 [features.field_presence = LEGACY_REQUIRED];
+  ScheduleStatus status = 2 [features.field_presence = LEGACY_REQUIRED];
+  Schedule schedule = 3 [features.field_presence = LEGACY_REQUIRED];
+  Delivery delivery = 4 [features.field_presence = LEGACY_REQUIRED];
+  Message message = 5 [features.field_presence = LEGACY_REQUIRED];
+}

proto/trogonai/scheduler/schedules/v1/pause_schedule.proto

@@ -0,0 +1,7 @@
+edition = "2024";
+
+package trogonai.scheduler.schedules.v1;
+
+message PauseSchedule {
+  string schedule_id = 1 [features.field_presence = LEGACY_REQUIRED];
+}

proto/trogonai/scheduler/schedules/v1/remove_schedule.proto

@@ -0,0 +1,7 @@
+edition = "2024";
+
+package trogonai.scheduler.schedules.v1;
+
+message RemoveSchedule {
+  string schedule_id = 1 [features.field_presence = LEGACY_REQUIRED];
+}

proto/trogonai/scheduler/schedules/v1/resume_schedule.proto

@@ -0,0 +1,7 @@
+edition = "2024";
+
+package trogonai.scheduler.schedules.v1;
+
+message ResumeSchedule {
+  string schedule_id = 1 [features.field_presence = LEGACY_REQUIRED];
+}

rsworkspace/.cargo/config.toml

@@ -1,8 +1,21 @@
 [alias]
+# Exclude sources the host coverage run cannot meaningfully measure:
+#   - Codegen output (proto/semconv `src/gen`) is not hand-authored.
+#   - The WASM decider guest (`trogon-decider-guest-sdk` glue + `wasm-components/*`)
+#     executes inside the component, so host `llvm-cov` never instruments it; its
+#     behavior is covered by the sim host integration tests and the YAML conformance
+#     suite instead.
+#   - `trogon-decider-test` is the conformance CLI / test harness, not shipped logic.
 cov = [
     "llvm-cov",
     "--all-features",
     "--workspace",
     "--ignore-filename-regex",
-    "crates/(trogonai-proto|trogon-semconv)/src/gen/.*",
+    "crates/(trogonai-proto|trogon-semconv)/src/gen/.*|crates/trogon-decider-guest-sdk/.*|wasm-components/.*|cli/trogon-decider-test/.*",
 ]
+
+[target.wasm32-wasip2]
+rustflags = ['--cfg', 'getrandom_backend="unsupported"']
+
+[target.wasm32-unknown-unknown]
+rustflags = ['--cfg', 'getrandom_backend="unsupported"']