build.sh

#!/usr/bin/env bash
# Synapse Agriculture — WASM build pipeline
# Run from workspace root inside `nix develop`
#
# This script enforces the correct build ordering:
#   1. Native tests (fastest feedback loop)
#   2. WASM compilation (catches target-specific issues)
#   3. Size profiling (validates MCU memory budget)
#   4. Runtime validation (wasm3 / wasmtime)
#
# Each step gates the next — fail fast, don't waste time.

set -euo pipefail

RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
CYAN='\033[0;36m'
NC='\033[0m'

WASM_TARGET="wasm32-unknown-unknown"
WASI_TARGET="wasm32-wasip1"
SENSOR_WASM="target/${WASM_TARGET}/release/synapse_sensor.wasm"
OPTIMIZED_WASM="target/wasm-opt/synapse_sensor.wasm"

# MCU memory budget (RP2350: 520KB total SRAM)
# wasm3 runtime: ~64KB, LoRa + HAL: ~48KB, heap: ~100KB
# Leaves roughly 300KB for the WASM module binary
MAX_WASM_SIZE_KB=300

step() { echo -e "\n${CYAN}═══ $1 ═══${NC}\n"; }
pass() { echo -e "${GREEN}  ✓ $1${NC}"; }
fail() { echo -e "${RED}  ✗ $1${NC}"; exit 1; }
warn() { echo -e "${YELLOW}  ⚠ $1${NC}"; }

# ── Step 1: Native tests ──────────────────────────────────────────────────
# Run all tests on the host architecture (x86_64).
# This validates shared types, calibration math, CBOR serialization,
# and ASCII parsing WITHOUT any WASM complexity.
# This is your fastest iteration loop — stay here until green.

step "Step 1: Native tests (all crates)"
cargo test --workspace --quiet 2>&1
pass "All native tests passed"

# ── Step 2: Compile sensor module to WASM ─────────────────────────────────
# Target: wasm32-unknown-unknown (bare WASM, no WASI)
# This is what runs on the MCU via wasm3.
# cdylib crate-type in synapse-sensor produces the .wasm file.
# release profile uses opt-level=z, LTO, panic=abort, strip=true
# for minimum binary size.

step "Step 2: Compile synapse-sensor → WASM (MCU target)"
cargo build \
    --package synapse-sensor \
    --target "${WASM_TARGET}" \
    --release \
    --quiet 2>&1

if [ ! -f "${SENSOR_WASM}" ]; then
    fail "WASM binary not found at ${SENSOR_WASM}"
fi

RAW_SIZE=$(wc -c < "${SENSOR_WASM}")
RAW_SIZE_KB=$((RAW_SIZE / 1024))
pass "Raw WASM binary: ${RAW_SIZE_KB}KB (${RAW_SIZE} bytes)"

# ── Step 3: Optimize for size ─────────────────────────────────────────────
# wasm-opt from Binaryen does aggressive dead code elimination,
# constant folding, and code deduplication. The -Oz flag optimizes
# purely for size (vs -O4 which optimizes for speed).
# This typically cuts Rust WASM binaries by 40-60%.

step "Step 3: Size optimization (wasm-opt -Oz)"
mkdir -p "$(dirname ${OPTIMIZED_WASM})"
wasm-opt -Oz \
    --strip-debug \
    --strip-producers \
    -o "${OPTIMIZED_WASM}" \
    "${SENSOR_WASM}" 2>&1

OPT_SIZE=$(wc -c < "${OPTIMIZED_WASM}")
OPT_SIZE_KB=$((OPT_SIZE / 1024))
SAVINGS=$(( (RAW_SIZE - OPT_SIZE) * 100 / RAW_SIZE ))
pass "Optimized WASM: ${OPT_SIZE_KB}KB (${OPT_SIZE} bytes, ${SAVINGS}% reduction)"

# ── Step 4: MCU memory budget check ──────────────────────────────────────
# Hard gate: if the module exceeds the RP2350 memory budget, stop.
# Better to catch this now than when flashing hardware in the field.

step "Step 4: MCU memory budget check (max ${MAX_WASM_SIZE_KB}KB)"
if [ "${OPT_SIZE_KB}" -gt "${MAX_WASM_SIZE_KB}" ]; then
    fail "WASM module (${OPT_SIZE_KB}KB) exceeds MCU budget (${MAX_WASM_SIZE_KB}KB)"
    echo "  Run: twiggy top ${OPTIMIZED_WASM}"
    echo "  to find what's taking space"
    exit 1
fi
pass "Module fits in MCU budget: ${OPT_SIZE_KB}KB / ${MAX_WASM_SIZE_KB}KB"

# ── Step 5: Size profiling ────────────────────────────────────────────────
# Even if we're under budget, know where the bytes are going.
# twiggy shows the top functions by size — if serde or fmt
# machinery snuck in, you'll see it here.

step "Step 5: Size profile (top 15 largest items)"
if command -v twiggy &>/dev/null; then
    twiggy top "${OPTIMIZED_WASM}" -n 15 2>&1 || warn "twiggy failed (non-fatal)"
else
    warn "twiggy not found — skip size profiling"
fi

# ── Step 6: WASM validation ──────────────────────────────────────────────
# wasm-tools validate checks the module against the WASM spec.
# Catches issues like invalid opcodes, type mismatches, or
# features the MCU runtime doesn't support.

step "Step 6: WASM module validation"
if command -v wasm-tools &>/dev/null; then
    wasm-tools validate "${OPTIMIZED_WASM}" 2>&1
    pass "Module passes WASM spec validation"
else
    warn "wasm-tools not found — skip validation"
fi

# ── Step 7: Export inspection ─────────────────────────────────────────────
# Verify the module exports the expected guest functions.
# The wasm3 runtime on the MCU will look for these by name.

step "Step 7: Export verification"
if command -v wasm-tools &>/dev/null; then
    EXPORTS=$(wasm-tools dump "${OPTIMIZED_WASM}" 2>/dev/null | grep -c "export" || echo "0")
    echo "  Module has ${EXPORTS} exports"

    # Check for our required guest functions
    for func in guest_init guest_sample guest_reconfigure; do
        if wasm2wat "${OPTIMIZED_WASM}" 2>/dev/null | grep -q "\"${func}\""; then
            pass "Found export: ${func}"
        else
            fail "Missing required export: ${func}"
        fi
    done
else
    warn "wasm-tools not found — skip export check"
fi

# ── Step 8: Import verification ───────────────────────────────────────────
# Verify the module imports match what the MCU host firmware provides.
# Any import the host doesn't implement = crash at instantiation.

step "Step 8: Import verification (host function dependencies)"
if command -v wabt &>/dev/null && command -v wasm2wat &>/dev/null; then
    echo "  Required host functions:"
    wasm2wat "${OPTIMIZED_WASM}" 2>/dev/null \
        | grep '(import' \
        | sed 's/.*"\([^"]*\)".*/    → \1/' \
        || warn "Could not extract imports"
else
    warn "wabt not found — skip import check"
fi

# ── Summary ───────────────────────────────────────────────────────────────
step "BUILD COMPLETE"
echo -e "  ${GREEN}Native tests:   PASS${NC}"
echo -e "  ${GREEN}WASM compile:   PASS${NC}"
echo -e "  ${GREEN}Size budget:    ${OPT_SIZE_KB}KB / ${MAX_WASM_SIZE_KB}KB${NC}"
echo -e "  ${GREEN}Spec valid:     PASS${NC}"
echo ""
echo "  Artifacts:"
echo "    Raw:       ${SENSOR_WASM}"
echo "    Optimized: ${OPTIMIZED_WASM}"
echo ""
echo "  Next steps:"
echo "    wasmtime (WASI):  needs wasm32-wasip1 target build"
echo "    wasm3 (MCU sim):  wasm3 ${OPTIMIZED_WASM} --func guest_sample"
echo "    Browser:          trunk serve crates/synapse-web"
echo ""