feat(L09): add load and store semantics card

tests/card_contract.test.mjs

@@ -0,0 +1,4 @@
+import assert from 'node:assert/strict'; import { readFile } from 'node:fs/promises'; import test from 'node:test';
+const source=JSON.parse(await readFile(new URL('../json/card_source.json',import.meta.url),'utf8'));
+test('L09 identity and three tasks are stable',()=>{assert.equal(source.card.number,'09');assert.equal(source.card.uuid,'f1efc445-93bd-5c0b-b531-52fc5a9ba943');assert.deepEqual(source.tasks_order,['task01','task02','task03']);});
+test('byte lanes, endian, extension and waveform evidence are explicit',()=>{const text=JSON.stringify(source);for(const token of ['strobe','little-endian','signed','fault','VCD'])assert.match(text,new RegExp(token,'i'));for(const task of Object.values(source.tasks))assert.equal(task.assessment_criterion_ref,'RV09.KW01');});

tests/card_state_db.test.mjs

@@ -0,0 +1,67 @@
+import assert from 'node:assert/strict';
+import { mkdtemp, rm } from 'node:fs/promises';
+import os from 'node:os';
+import path from 'node:path';
+import test from 'node:test';
+import { CardStateDatabase } from '../scripts/lib/card_state_db.mjs';
+
+test('card state survives closing and reopening SQLite', async () => {
+  const directory = await mkdtemp(path.join(os.tmpdir(), 'stem-card-state-'));
+  const file = path.join(directory, 'state.sqlite3');
+  const state = {
+    schema: 'stem-card-navigation.v2',
+    revision: 7,
+    selected_at: '2026-07-17T12:00:00.000Z',
+    snapshot_ref: 'task04.alloc5.cursor'
+  };
+
+  try {
+    const first = new CardStateDatabase(file);
+    first.write('navigation', state);
+    first.close();
+
+    const second = new CardStateDatabase(file);
+    assert.deepEqual(second.read('navigation'), state);
+    assert.equal(second.read('missing'), null);
+    second.close();
+  } finally {
+    await rm(directory, { recursive: true, force: true });
+  }
+});
+
+test('audit log is append-only, ordered and keeps navigation timestamps', async () => {
+  const directory = await mkdtemp(path.join(os.tmpdir(), 'stem-card-audit-'));
+  const file = path.join(directory, 'state.sqlite3');
+  try {
+    const database = new CardStateDatabase(file);
+    const navigation = {
+      task: { id: 'task04' },
+      block: { id: 'allocator-flow' },
+      phase: { id: 'alloc5' },
+      step: { id: 'alloc5-commit' },
+      snapshot_ref: 'task04.alloc5.commit'
+    };
+    const first = database.appendEvent({
+      eventType: 'navigation.activate',
+      actor: 'nvim',
+      navigation,
+      occurredAt: '2026-07-17T12:00:00.000Z',
+      payload: { source: 'F2' }
+    });
+    const second = database.appendEvent({
+      eventType: 'checkpoint.ready',
+      actor: 'nvim',
+      navigation,
+      occurredAt: '2026-07-17T12:00:01.000Z'
+    });
+    assert.equal(second.id, first.id + 1);
+    assert.deepEqual(
+      database.listEvents({ afterId: first.id, limit: 10 }).map(event => event.event_type),
+      ['checkpoint.ready']
+    );
+    assert.equal(database.listEvents()[0].snapshot_ref, navigation.snapshot_ref);
+    database.close();
+  } finally {
+    await rm(directory, { recursive: true, force: true });
+  }
+});

tests/reference_model.py

@@ -0,0 +1,34 @@
+#!/usr/bin/env python3
+import sys
+
+
+def task01():
+    assert (1 << 3) == 0b1000 and (0b11 << 2) == 0b1100
+    assert ((0xAA << 24) & 0xFFFFFFFF) == 0xAA000000
+    assert ((0xBEEF << 16) & 0xFFFFFFFF) == 0xBEEF0000
+    print("PASS task01 sb_strobe=1000 sb_data=aa000000 sh_strobe=1100 sh_data=beef0000 sw_strobe=1111 fault=1")
+
+
+def sign_extend(value, bits):
+    return (value | (~0 << bits)) & 0xFFFFFFFF if value & (1 << (bits - 1)) else value
+
+
+def task02():
+    word = 0x80FF7F01
+    assert sign_extend((word >> 24) & 0xFF, 8) == 0xFFFFFF80
+    assert ((word >> 24) & 0xFF) == 0x80
+    assert sign_extend((word >> 16) & 0xFFFF, 16) == 0xFFFF80FF
+    print("PASS task02 lb=ffffff80 lbu=00000080 lh=ffff80ff lhu=000080ff")
+
+
+def task03():
+    word = 0x11223344
+    word = (word & ~(0xFF << 8)) | (0xAA << 8)
+    assert word == 0x1122AA44 and sign_extend(0xAA, 8) == 0xFFFFFFAA
+    print("PASS task03 word=1122aa44 lb=ffffffaa lbu=000000aa fault=1")
+
+
+TASKS = {"task01_store_lanes": task01, "task02_load_extend": task02, "task03_load_store_unit": task03}
+if len(sys.argv) != 2 or sys.argv[1] not in TASKS:
+    raise SystemExit(f"usage: {sys.argv[0]} {'|'.join(TASKS)}")
+TASKS[sys.argv[1]]()

tests/task01_store_lanes_tb.sv

@@ -0,0 +1,21 @@
+module tb;
+    logic [1:0] address_low;
+    logic [2:0] funct3;
+    logic [31:0] store_value, bus_write_data;
+    logic [3:0] write_strobe;
+    logic fault;
+    string trace_file;
+    store_lanes dut (.*);
+    initial begin
+        if ($value$plusargs("trace=%s", trace_file)) begin $dumpfile(trace_file); $dumpvars(0, tb); end
+        address_low=3; funct3=0; store_value=32'haa; #1;
+        if (write_strobe!==4'b1000 || bus_write_data!==32'haa000000 || fault) $fatal(1,"FAIL SB");
+        address_low=2; funct3=1; store_value=32'hbeef; #1;
+        if (write_strobe!==4'b1100 || bus_write_data!==32'hbeef0000 || fault) $fatal(1,"FAIL SH");
+        address_low=0; funct3=2; store_value=32'h12345678; #1;
+        if (write_strobe!==4'b1111 || bus_write_data!==store_value || fault) $fatal(1,"FAIL SW");
+        address_low=1; funct3=1; #1; if (!fault || write_strobe!==0) $fatal(1,"FAIL misaligned");
+        $display("PASS task01 sb_strobe=1000 sb_data=aa000000 sh_strobe=1100 sh_data=beef0000 sw_strobe=1111 fault=1");
+        $finish;
+    end
+endmodule

tests/task02_load_extend_tb.sv

@@ -0,0 +1,18 @@
+module tb;
+    logic [31:0] memory_word, read_data;
+    logic [1:0] address_low;
+    logic [2:0] funct3;
+    logic fault;
+    string trace_file;
+    load_extend dut (.*);
+    initial begin
+        if ($value$plusargs("trace=%s", trace_file)) begin $dumpfile(trace_file); $dumpvars(0, tb); end
+        memory_word=32'h80ff7f01; address_low=3; funct3=0; #1; if(read_data!==32'hffffff80||fault)$fatal(1,"FAIL LB %h",read_data);
+        funct3=4; #1; if(read_data!==32'h80||fault)$fatal(1,"FAIL LBU %h",read_data);
+        address_low=2; funct3=1; #1; if(read_data!==32'hffff80ff||fault)$fatal(1,"FAIL LH %h",read_data);
+        funct3=5; #1; if(read_data!==32'h80ff||fault)$fatal(1,"FAIL LHU %h",read_data);
+        address_low=0; funct3=2; #1; if(read_data!==memory_word||fault)$fatal(1,"FAIL LW %h",read_data);
+        $display("PASS task02 lb=ffffff80 lbu=00000080 lh=ffff80ff lhu=000080ff");
+        $finish;
+    end
+endmodule

tests/task03_load_store_unit_tb.sv

@@ -0,0 +1,24 @@
+module tb;
+    logic clk=0, request=0, write_enable=0;
+    logic [31:0] address=0, write_data=0, read_data;
+    logic [2:0] funct3=0;
+    logic fault;
+    string trace_file;
+    load_store_unit dut (.*);
+    always #1 clk=~clk;
+    task automatic store(input logic [31:0] addr, input logic [2:0] size, input logic [31:0] data);
+        @(negedge clk); request=1; write_enable=1; address=addr; funct3=size; write_data=data;
+        @(posedge clk); #1;
+    endtask
+    initial begin
+        if ($value$plusargs("trace=%s", trace_file)) begin $dumpfile(trace_file); $dumpvars(0, tb); end
+        store(0,2,32'h11223344); store(1,0,32'haa);
+        @(negedge clk); write_enable=0; address=0; funct3=2; #1;
+        if(read_data!==32'h1122aa44||fault)$fatal(1,"FAIL word=%h",read_data);
+        address=1; funct3=0; #1; if(read_data!==32'hffffffaa||fault)$fatal(1,"FAIL LB=%h",read_data);
+        funct3=4; #1; if(read_data!==32'haa||fault)$fatal(1,"FAIL LBU=%h",read_data);
+        address=2; funct3=2; #1; if(!fault||read_data!==0)$fatal(1,"FAIL fault=%b data=%h",fault,read_data);
+        $display("PASS task03 word=1122aa44 lb=ffffffaa lbu=000000aa fault=1");
+        $finish;
+    end
+endmodule

tests/test_rtl.sh

@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+set -euo pipefail
+root="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")/.." && pwd)"
+mode=test
+if [[ "${1:-}" == "--build-only" || "${1:-}" == "--trace" ]]; then mode="${1#--}"; shift; fi
+task="${1:?task name is required}"
+case "$task" in task01_store_lanes|task02_load_extend|task03_load_store_unit) ;; *) printf 'Unknown RTL task: %s\n' "$task" >&2; exit 2 ;; esac
+state="${STEM_STATE_DIR:-$root/.stem/instances/local}"
+profile="${STEM_PROFILE:-hazard3-sim}"
+target="${STEM_TARGET:-hazard3-baremetal}"
+build_dir="$state/build/rtl/$task"
+artifact_dir="$root/.stem/artifacts/$profile/$target/$task"
+binary="$build_dir/sim"
+mkdir -p "$build_dir" "$artifact_dir"
+verilator --binary --timing --assert --trace -Wall -Wno-fatal -Wno-DECLFILENAME -Wno-BLKSEQ -Wno-UNUSEDSIGNAL --top-module tb --Mdir "$build_dir/obj" -o "$binary" "$root/src/tasks/$task.sv" "$root/tests/${task}_tb.sv" >/dev/null
+cp -f "$root/src/tasks/$task.sv" "$artifact_dir/"
+[[ "$mode" == build-only ]] && { printf 'BUILD %s binary=%s\n' "$task" "$binary"; exit 0; }
+trace_file="$artifact_dir/$task.vcd"
+if [[ "$mode" == trace ]]; then "$binary" "+trace=$trace_file"; test -s "$trace_file"; printf 'TRACE %s vcd=%s\n' "$task" "$trace_file"; else "$binary"; fi