more

2026-07-20 16:34:19 -04:00
parent a87c9576fc
commit 42c96a31a2
11 changed files with 572 additions and 86 deletions
@@ -16,15 +16,16 @@ touching QEMU internals. Pairs with `ROADMAP.md` (the plan) — this is the
  `0002-qemu-wasm.patch` ports qemu-wasm's host backend onto the same pinned
  Espressif QEMU commit `40edccac415693c5130f91c01d84176ae6008566`.
 - `make qemu-wasm` produces a smoke-tested ES module, WASM binary, and pthread
-  worker under `dist/wasm/`. Next: static browser UI. Full X4 rendering waits.
+  worker under `dist/wasm/`; the static browser UI boots firmware, renders X3,
+  drives buttons, and exposes SD files/debug metrics. Full X4 rendering waits.

 ---

 ## 1. Environment / hardware realities (READ FIRST)

- **The dev box is ~15 yr old, 4 GB RAM.** A full QEMU build is ~1660 objects
-  and takes a long time. **Always `-j2`** (more OOMs the linker) and use
-  **very long timeouts (I used 7200 s)** for any `ninja`/`pio`/`nix build`.
+- A full QEMU build is large and can take several minutes. Build parallelism
+  defaults to `nproc`; set `JOBS` lower if memory pressure requires it and use
+  long timeouts for any `ninja`/`pio`/`nix build`.
  Do not treat a long-running build as hung.
 - **First full QEMU build ≈ many minutes; incremental after a patch edit is
  seconds** (only the touched `.c` + relink). Iterate incrementally; never
@@ -174,8 +175,8 @@ Base addresses from ESP-IDF `soc/esp32c3` headers; all confirmed live.
 - creates the selected panel on `spi2.bus`, wires GPIO out 21→CS, 4→DC, 5→RST,
  and panel BUSY→GPIO in 6 (X3 UC8253 renders; X4 SSD1677 is a blank stub);
 - creates `ssi-sd` at CS index 1 on `spi2.bus`, wires GPIO out 12→its CS, and a
-  `sd-card-spi` backed by `drive_get(IF_SD, 0, 0)` (QEMU block layer — the SD
-  "interface" you asked for; local `-drive` now, browser blockdev later);
+  `sd-card-spi` backed by `drive_get(IF_SD, 0, 0)`. Native uses a raw image;
+  WASM uses QEMU `vvfat` over the JS-created MEMFS `/sdcard` directory;
 - **defaults both CS lines high** at init (`qemu_set_irq(cs, 1)`) so nothing is
  selected before the firmware drives GPIO.

@@ -283,21 +284,26 @@ ADC ladders on GPIO1 & GPIO2; power button GPIO3; UC8253 @ 16 MHz.
 - The narrow browser bridge exports panel surface metadata/pixels and atomic
  ADC/GPIO setters. JS polls a frame generation counter and forces alpha to 255;
  X3's native surface stores RGB with a zero alpha byte.
- Firmware and ROM are written to MEMFS before QEMU starts. A second boot needs
-  a page reload because QEMU machine selection and global state are process-wide.
+- Firmware and ROM are written to MEMFS before QEMU starts. Browser SD uses
+  QEMU `vvfat` to expose `/sdcard` as a writable 32 GiB FAT32 volume; memory
+  scales with actual directory files plus about 5 MiB of FAT/write bookkeeping,
+  not logical capacity. The initial JS provider creates `Test/example.txt`.
+- The inspector has Logs, Files, and Debug tabs. Debug reports committed WASM
+  heap (176.3 MiB after a 90-second validation run), visible MEMFS bytes, SD file
+  bytes, and browser JS heap when supported.
+- A second boot needs a page reload because QEMU machine selection and global
+  state are process-wide.

 Next:

-0. **Boot stall**: firmware freezes after X3 panel init (display generation stays
-   at 2). Compare against native `make run` (which reaches the home screen);
-   suspect timers/interrupts or just slow TCG. `_scratch/dump-fb3.mjs` reproduces.
-1. **Browser SD storage**: add an uploaded or OPFS-backed SD block device.
+1. **Browser SD editing/persistence**: add file controls and optionally OPFS.
+   Live host-side changes to a mounted FAT volume are intentionally accepted as
+   unsafe; editing is not implemented yet.

-> Patch workflow: `scripts/build-qemu-wasm.sh` only re-applies
-> `qemu/patches/0002-qemu-wasm.patch` when the WASM source tree lacks the xteink
-> files. After editing the patch, `rm -rf _scratch/qemu-wasm-src` so `make
-> qemu-wasm` re-clones and re-applies it. The patch is regenerated from the
-> `_scratch/qemu-fix-src` worktree via `git diff --binary 610f8c69..HEAD`.
+> Patch workflow: `scripts/build-qemu-wasm.sh` resets/reapplies patches when
+> either patch is newer than `.xteink-patch-stamp`. Regenerate patch 0002 from
+> `_scratch/qemu-fix-src` with `git diff --binary 610f8c69 >
+> qemu/patches/0002-qemu-wasm.patch`.
 2. **Full X4 rendering later**: SSD1677 is 800×480 controller / 480×800 portrait,
   BUSY active-high. Implement its RAM/window/update commands when needed.

@@ -9,7 +9,7 @@ QEMU_WASM_SRC ?= _scratch/qemu-wasm-src
 WASM_OUT ?= dist/wasm
 VARIANT ?= x3

-.PHONY: firmware sdimage blank-sd-asset qemu qemu-wasm web web-test run run-upstream chip clean
+.PHONY: firmware sdimage qemu qemu-wasm web web-test run run-upstream chip clean

 firmware:
 	esptool --chip esp32c3 merge-bin -o flash.bin \
@@ -23,12 +23,6 @@ firmware:
 sdimage:
 	scripts/mksd.sh $(SD_SRC) sd.img

-blank-sd-asset:
-	@tmpdir=$$(mktemp -d); trap 'rm -rf "$$tmpdir"' EXIT; \
-	  mkdir "$$tmpdir/empty"; \
-	  SIZE_MB=64 scripts/mksd.sh "$$tmpdir/empty" "$$tmpdir/sd.img"; \
-	  gzip -n -9 -c "$$tmpdir/sd.img" > web/assets/blank-sd.img.gz
-
 qemu:
 	QEMU_SRC=$(QEMU_SRC) scripts/build-qemu.sh

@@ -18,7 +18,7 @@ buttons. See [ROADMAP.md](./ROADMAP.md) for architecture and plan.
 git clone --recursive https://github.com/crosspoint-reader/crosspoint-reader ../crosspoint-reader
 # Build ../crosspoint-reader's PlatformIO `default` environment first.
 nix develop
-make qemu             # clone espressif/qemu @ pinned commit, apply patch, build (JOBS=2)
+make qemu             # clone espressif/qemu @ pinned commit, apply patch, build
 make firmware sdimage # 16 MB flash.bin + FAT32 sd.img from the PlatformIO build
 make run              # X3 (default)
 make run VARIANT=x4   # X4 detection + blank SSD1677 stub
@@ -54,11 +54,12 @@ map to the device's ADC button ladders and active-low Power GPIO. `make web`
 serves the required COOP/COEP headers for Emscripten pthreads; a generic static
 server without those headers will not work.

-Real firmware now boots in WASM: it runs past the earlier allocator and
-function-pointer signature crashes and initializes the X3 panel (528×792). It
-still stalls before painting a full home screen (the display generation counter
-freezes after early init), so end-to-end boot is not complete. X4 remains a
-white display stub, and browser SD storage is not implemented yet.
+Real firmware boots in WASM and drives the X3 panel (528×792). The browser SD
+uses QEMU's directory-backed FAT provider: the guest sees a writable, ephemeral
+32 GiB FAT32 card while memory use scales with actual files instead of logical
+capacity. It starts with `Test/example.txt`; inspect it in the Files tab. The
+Debug tab reports committed WASM heap, visible MEMFS data, SD file bytes, and
+browser JS heap where supported. X4 remains a white display stub.

 ## Contents

@@ -38,9 +38,8 @@ X4 SPI traffic confirmed the firmware selected its SSD1677 driver.
 `make qemu-wasm` produces the Emscripten module, WASM binary, and pthread worker
 under `dist/wasm/`; Node smoke checks confirm `xteink` is registered and its
 browser framebuffer/input bridge initializes. `make web` serves a dependency-free
-UI for firmware, canvas, and buttons. Real firmware now boots past the allocator
-and function-pointer crashes and initializes the X3 panel, but still stalls
-before painting a full home screen.
+UI for firmware, canvas, buttons, logs, SD files, and debug metrics. Real
+firmware boots in WASM and drives the X3 panel.

 ### Device selection (X3 vs X4)

@@ -59,7 +58,7 @@ reuses unchanged — no bespoke abstraction layer:
 | Peripheral | Native seam | Browser binding |
 |------------|-------------|---------------------------|
 | e-ink panel | X3 UC8253 (528×792) or blank X4 SSD1677 stub (480×800) → QEMU graphical console | `<canvas>` from the same display surface |
-| SD card | `ssi-sd` + `sd-card-spi` backed by QEMU block layer (`-drive if=sd`) | browser-supplied blockdev (File/OPFS) |
+| SD card | `ssi-sd` + `sd-card-spi` backed by QEMU block layer (`-drive if=sd`) | QEMU `vvfat` over a JS-created MEMFS directory; future persistence can use OPFS |
 | Buttons + battery | ADC QOM props `adci[1]`/`adci[2]`; GPIO QOM `input-level[3]` for Power | DOM buttons → `qom-set` equivalent |
 | Firmware image | flash via `-drive if=mtd` | uploaded `.bin` written to emulated flash |

@@ -86,8 +85,8 @@ reuses unchanged — no bespoke abstraction layer:

 ## Remaining phases

-1. **Browser SD storage** — add an uploaded or OPFS-backed SD block device. The
-   basic static frontend already covers firmware, canvas, buttons, and X3/X4.
+1. **Browser SD editing/persistence** — add file controls and optionally OPFS;
+   the current 32 GiB logical card is writable and ephemeral.
 2. **Full X4 panel** — implement SSD1677 RAM/window/update commands when visible
   X4 rendering is needed; the selection, dimensions, wiring, and stub exist.

@@ -224,6 +224,30 @@ index 49814ec4af..0715610d37 100644
     assert(tcg_enabled());
     g_assert(!icount_enabled());
 
+diff --git c/accel/tcg/tcg-accel-ops-rr.c w/accel/tcg/tcg-accel-ops-rr.c
+index 8ebadf8e9e..1e38df86e8 100644
+--- c/accel/tcg/tcg-accel-ops-rr.c
+++ w/accel/tcg/tcg-accel-ops-rr.c
+@@ -177,11 +177,19 @@ static int rr_cpu_count(void)
+  * elsewhere.
+  */
+ 
+#if defined(EMSCRIPTEN) && !defined(CONFIG_TCG_INTERPRETER)
+#include "../../tcg/wasm32.h"
+#endif
+
+ static void *rr_cpu_thread_fn(void *arg)
+ {
+     Notifier force_rcu;
+     CPUState *cpu = arg;
+ 
+#if defined(EMSCRIPTEN) && !defined(CONFIG_TCG_INTERPRETER)
+    init_wasm32();
+#endif
+
+     assert(tcg_enabled());
+     rcu_register_thread();
+     force_rcu.notify = rr_force_rcu;
 diff --git c/backends/meson.build w/backends/meson.build
 index da714b93d1..9b88d22685 100644
 --- c/backends/meson.build
@@ -278,6 +302,223 @@ index 90fa54352c..0fa9cc31b6 100644
 
 /*
  * parse_zone - Fill a zone descriptor
+diff --git c/block/vvfat.c w/block/vvfat.c
+index 8ffe8b3b9b..4cf02d9a55 100644
+--- c/block/vvfat.c
+++ w/block/vvfat.c
+@@ -749,6 +749,7 @@ static int read_directory(BDRVVVFATState* s, int mapping_index)
+     const char* dirname = mapping->path;
+     int first_cluster = mapping->begin;
+     int parent_index = mapping->info.dir.parent_mapping_index;
+    bool is_root = parent_index < 0;
+     mapping_t* parent_mapping = (mapping_t*)
+         (parent_index >= 0 ? array_get(&(s->mapping), parent_index) : NULL);
+     int first_cluster_of_parent = parent_mapping ? parent_mapping->begin : -1;
+@@ -765,9 +766,9 @@ static int read_directory(BDRVVVFATState* s, int mapping_index)
+     }
+ 
+     i = mapping->info.dir.first_dir_index =
+-            first_cluster == 0 ? 0 : s->directory.next;
+            is_root ? 0 : s->directory.next;
+ 
+-    if (first_cluster != 0) {
+    if (!is_root) {
+         /* create the top entries of a subdirectory */
+         (void)create_short_and_long_name(s, i, ".", 1);
+         (void)create_short_and_long_name(s, i, "..", 1);
+@@ -781,13 +782,14 @@ static int read_directory(BDRVVVFATState* s, int mapping_index)
+         int is_dot=!strcmp(entry->d_name,".");
+         int is_dotdot=!strcmp(entry->d_name,"..");
+ 
+-        if (first_cluster == 0 && s->directory.next >= s->root_entries - 1) {
+        if (is_root && s->fat_type != 32 &&
+            s->directory.next >= s->root_entries - 1) {
+             fprintf(stderr, "Too many entries in root directory\n");
+             closedir(dir);
+             return -2;
+         }
+ 
+-        if(first_cluster == 0 && (is_dotdot || is_dot))
+        if(is_root && (is_dotdot || is_dot))
+             continue;
+ 
+         buffer = g_malloc(length);
+@@ -860,8 +862,7 @@ static int read_directory(BDRVVVFATState* s, int mapping_index)
+         memset(direntry,0,sizeof(direntry_t));
+     }
+ 
+-    if (s->fat_type != 32 &&
+-        mapping_index == 0 &&
+    if (s->fat_type != 32 && is_root &&
+         s->directory.next < s->root_entries) {
+         /* root directory */
+         int cur = s->directory.next;
+@@ -877,20 +878,24 @@ static int read_directory(BDRVVVFATState* s, int mapping_index)
+         * 0x20 / s->cluster_size;
+     mapping->end = first_cluster;
+ 
+-    direntry = array_get(&(s->directory), mapping->dir_index);
+-    set_begin_of_direntry(direntry, mapping->begin);
+    if (!is_root) {
+        direntry = array_get(&(s->directory), mapping->dir_index);
+        set_begin_of_direntry(direntry, mapping->begin);
+    }
+ 
+     return 0;
+ }
+ 
+ static inline int32_t sector2cluster(BDRVVVFATState* s,off_t sector_num)
+ {
+-    return (sector_num - s->offset_to_root_dir) / s->sectors_per_cluster;
+    return (sector_num - s->offset_to_root_dir) / s->sectors_per_cluster
+        + (s->fat_type == 32 ? 2 : 0);
+ }
+ 
+ static inline off_t cluster2sector(BDRVVVFATState* s, uint32_t cluster_num)
+ {
+-    return s->offset_to_root_dir + s->sectors_per_cluster * cluster_num;
+    return s->offset_to_root_dir + s->sectors_per_cluster
+        * (cluster_num - (s->fat_type == 32 ? 2 : 0));
+ }
+ 
+ static int init_directories(BDRVVVFATState* s,
+@@ -934,11 +939,12 @@ static int init_directories(BDRVVVFATState* s,
+     init_fat(s);
+ 
+     /* TODO: if there are more entries, bootsector has to be adjusted! */
+-    s->root_entries = 0x02 * 0x10 * s->sectors_per_cluster;
+    s->root_entries = s->fat_type == 32 ? 0 :
+        0x02 * 0x10 * s->sectors_per_cluster;
+     s->cluster_count=sector2cluster(s, s->sector_count);
+ 
+     mapping = array_get_next(&(s->mapping));
+-    mapping->begin = 0;
+    mapping->begin = s->fat_type == 32 ? 2 : 0;
+     mapping->dir_index = 0;
+     mapping->info.dir.parent_mapping_index = -1;
+     mapping->first_mapping_index = -1;
+@@ -950,11 +956,10 @@ static int init_directories(BDRVVVFATState* s,
+     mapping->read_only = 0;
+     s->path = mapping->path;
+ 
+-    for (i = 0, cluster = 0; i < s->mapping.next; i++) {
+-        /* MS-DOS expects the FAT to be 0 for the root directory
+-         * (except for the media byte). */
+-        /* LATER TODO: still true for FAT32? */
+-        int fix_fat = (i != 0);
+    for (i = 0, cluster = s->fat_type == 32 ? 2 : 0;
+         i < s->mapping.next; i++) {
+        /* FAT12/16 stores the root directory outside the cluster chain. */
+        int fix_fat = (i != 0 || s->fat_type == 32);
+         mapping = array_get(&(s->mapping), i);
+ 
+         if (mapping->mode & MODE_DIRECTORY) {
+@@ -1026,22 +1031,35 @@ static int init_directories(BDRVVVFATState* s,
+     /* media descriptor: hard disk=0xf8, floppy=0xf0 */
+     bootsector->media_type = (s->offset_to_bootsector > 0 ? 0xf8 : 0xf0);
+     s->fat.pointer[0] = bootsector->media_type;
+-    bootsector->sectors_per_fat=cpu_to_le16(s->sectors_per_fat);
+    bootsector->sectors_per_fat = s->fat_type == 32 ? 0 :
+        cpu_to_le16(s->sectors_per_fat);
+     bootsector->sectors_per_track = cpu_to_le16(secs);
+     bootsector->number_of_heads = cpu_to_le16(heads);
+     bootsector->hidden_sectors = cpu_to_le32(s->offset_to_bootsector);
+     bootsector->total_sectors=cpu_to_le32(s->sector_count>0xffff?s->sector_count:0);
+ 
+-    /* LATER TODO: if FAT32, this is wrong */
+-    /* drive_number: fda=0, hda=0x80 */
+-    bootsector->u.fat16.drive_number = s->offset_to_bootsector == 0 ? 0 : 0x80;
+-    bootsector->u.fat16.signature=0x29;
+-    bootsector->u.fat16.id=cpu_to_le32(0xfabe1afd);
+-
+-    memcpy(bootsector->u.fat16.volume_label, s->volume_label,
+-           sizeof(bootsector->u.fat16.volume_label));
+-    memcpy(bootsector->u.fat16.fat_type,
+-           s->fat_type == 12 ? "FAT12   " : "FAT16   ", 8);
+    if (s->fat_type == 32) {
+        bootsector->u.fat32.sectors_per_fat = cpu_to_le32(s->sectors_per_fat);
+        bootsector->u.fat32.first_cluster_of_root_dir = cpu_to_le32(2);
+        bootsector->u.fat32.info_sector = cpu_to_le16(0xffff);
+        bootsector->u.fat32.backup_boot_sector = cpu_to_le16(0xffff);
+        bootsector->u.fat32.drive_number = 0x80;
+        bootsector->u.fat32.signature = 0x29;
+        bootsector->u.fat32.id = cpu_to_le32(0xfabe1afd);
+        memcpy(bootsector->u.fat32.volume_label, s->volume_label,
+               sizeof(bootsector->u.fat32.volume_label));
+        memcpy(bootsector->u.fat32.fat_type, "FAT32   ", 8);
+    } else {
+        /* drive_number: fda=0, hda=0x80 */
+        bootsector->u.fat16.drive_number =
+            s->offset_to_bootsector == 0 ? 0 : 0x80;
+        bootsector->u.fat16.signature=0x29;
+        bootsector->u.fat16.id=cpu_to_le32(0xfabe1afd);
+        memcpy(bootsector->u.fat16.volume_label, s->volume_label,
+               sizeof(bootsector->u.fat16.volume_label));
+        memcpy(bootsector->u.fat16.fat_type,
+               s->fat_type == 12 ? "FAT12   " : "FAT16   ", 8);
+    }
+     bootsector->magic[0]=0x55; bootsector->magic[1]=0xaa;
+ 
+     return 0;
+@@ -1139,6 +1157,7 @@ static int vvfat_open(BlockDriverState *bs, QDict *options, int flags,
+ {
+     BDRVVVFATState *s = bs->opaque;
+     int cyls, heads, secs;
+    uint64_t total_sectors;
+     bool floppy;
+     const char *dirname, *label;
+     QemuOpts *opts;
+@@ -1205,7 +1224,9 @@ static int vvfat_open(BlockDriverState *bs, QDict *options, int flags,
+ 
+     switch (s->fat_type) {
+     case 32:
+#ifndef EMSCRIPTEN
+         warn_report("FAT32 has not been tested. You are welcome to do so!");
+#endif
+         break;
+     case 16:
+     case 12:
+@@ -1219,8 +1240,17 @@ static int vvfat_open(BlockDriverState *bs, QDict *options, int flags,
+ 
+     s->bs = bs;
+ 
+-    /* LATER TODO: if FAT32, adjust */
+-    s->sectors_per_cluster=0x10;
+#ifdef EMSCRIPTEN
+    if (!floppy && s->fat_type == 32) {
+        /* Browser SD Geometry - A larger cluster keeps the synthesized 32 GiB FAT near 4 MiB. */
+        s->sectors_per_cluster = 0x40;
+        total_sectors = 32ULL * 1024 * 1024 * 1024 / BDRV_SECTOR_SIZE;
+    } else
+#endif
+    {
+        s->sectors_per_cluster = 0x10;
+        total_sectors = (uint64_t)cyls * heads * secs;
+    }
+ 
+     s->current_cluster=0xffffffff;
+ 
+@@ -1232,8 +1262,8 @@ static int vvfat_open(BlockDriverState *bs, QDict *options, int flags,
+     DLOG(fprintf(stderr, "vvfat %s chs %d,%d,%d\n",
+                  dirname, cyls, heads, secs));
+ 
+-    s->sector_count = cyls * heads * secs - s->offset_to_bootsector;
+-    bs->total_sectors = cyls * heads * secs;
+    s->sector_count = total_sectors - s->offset_to_bootsector;
+    bs->total_sectors = total_sectors;
+ 
+     if (qemu_opt_get_bool(opts, "rw", false)) {
+         if (!bdrv_is_read_only(bs)) {
+@@ -1523,7 +1553,8 @@ vvfat_read(BlockDriverState *bs, int64_t sector_num, uint8_t *buf, int nb_sector
+         } else {
+             uint32_t sector = sector_num - s->offset_to_root_dir,
+             sector_offset_in_cluster=(sector%s->sectors_per_cluster),
+-            cluster_num=sector/s->sectors_per_cluster;
+            cluster_num=sector/s->sectors_per_cluster
+                + (s->fat_type == 32 ? 2 : 0);
+             if(cluster_num > s->cluster_count || read_cluster(s, cluster_num) != 0) {
+                 /* LATER TODO: strict: return -1; */
+                 memset(buf+i*0x200,0,0x200);
 diff --git c/configs/devices/riscv32-softmmu/xteink.mak w/configs/devices/riscv32-softmmu/xteink.mak
 new file mode 100644
 index 0000000000..a9179b4119
@@ -613,6 +854,39 @@ index 1879b5c2df..e3f09cc51b 100644
 }
 
 static void esp32c3_cache_init(Object *obj)
+diff --git c/hw/misc/esp32c3_jtag.c w/hw/misc/esp32c3_jtag.c
+index 82ee69717b..64a971f183 100644
+--- c/hw/misc/esp32c3_jtag.c
+++ w/hw/misc/esp32c3_jtag.c
+@@ -16,10 +16,18 @@
+ #include "hw/misc/esp32c3_jtag.h"
+ 
+ 
+/* USB Serial JTAG Console Tap - The firmware routes ESP-IDF console output (incl. panic dumps) through this peripheral. EP1 is the byte FIFO; EP1_CONF bit1 (SERIAL_IN_EP_DATA_FREE) must read set so the driver believes the TX FIFO can always accept a byte. */
+#define ESP32C3_JTAG_EP1_REG       0x00
+#define ESP32C3_JTAG_EP1_CONF_REG  0x04
+#define ESP32C3_JTAG_IN_EP_DATA_FREE (1u << 1)
+
+ static uint64_t esp32c3_jtag_read(void *opaque, hwaddr addr, unsigned int size)
+ {
+     ESP32C3UsbJtagState *s = ESP32C3_JTAG(opaque);
+     (void) s;
+    if (addr == ESP32C3_JTAG_EP1_CONF_REG) {
+        return ESP32C3_JTAG_IN_EP_DATA_FREE;
+    }
+     return 0;
+ }
+ 
+@@ -27,6 +35,9 @@ static void esp32c3_jtag_write(void *opaque, hwaddr addr, uint64_t value, unsign
+ {
+     ESP32C3UsbJtagState *s = ESP32C3_JTAG(opaque);
+     (void) s;
+    if (addr == ESP32C3_JTAG_EP1_REG) {
+        fputc((int)(value & 0xff), stderr);
+    }
+ }
+ 
+ static const MemoryRegionOps esp32c3_jtag_ops = {
 diff --git c/hw/misc/esp_sha.c w/hw/misc/esp_sha.c
 index c9fa2e610a..cc186595eb 100644
 --- c/hw/misc/esp_sha.c
@@ -707,7 +981,7 @@ index c9fa2e610a..cc186595eb 100644
     },
 };
 diff --git c/hw/riscv/esp32c3.c w/hw/riscv/esp32c3.c
-index 2f1ccbfbb0..febc96bfe3 100644
+index 2f1ccbfbb0..af8bb86c97 100644
 --- c/hw/riscv/esp32c3.c
 +++ w/hw/riscv/esp32c3.c
@@ -57,6 +57,10 @@
@@ -721,7 +995,7 @@ index 2f1ccbfbb0..febc96bfe3 100644
 #define ESP32C3_IO_WARNING          0
 
 #define ESP32C3_RESET_ADDRESS       0x40000000
-@@ -103,6 +107,27 @@ struct Esp32C3MachineState {
+@@ -103,6 +107,29 @@ struct Esp32C3MachineState {
     Esp32C3TWAIState twai;
 };
 
@@ -732,6 +1006,7 @@ index 2f1ccbfbb0..febc96bfe3 100644
 +{
 +    if (xteink_wasm_machine && channel >= 0 &&
 +        channel < ESP32C3_ADC_CHANNELS) {
+        fprintf(stderr, "[button] adc channel=%d value=%u\n", channel, value);
 +        qatomic_set(&xteink_wasm_machine->adc.input[channel],
 +                    MIN(value, UINT32_C(0xfff)));
 +    }
@@ -740,6 +1015,7 @@ index 2f1ccbfbb0..febc96bfe3 100644
 +EMSCRIPTEN_KEEPALIVE void xteink_wasm_set_gpio(int pin, int level)
 +{
 +    if (xteink_wasm_machine && pin >= 0 && pin < ESP32_GPIO_COUNT) {
+        fprintf(stderr, "[button] gpio pin=%d level=%d\n", pin, level);
 +        esp32_gpio_set_input_level(&xteink_wasm_machine->gpio.parent,
 +                                   pin, level);
 +    }
@@ -749,7 +1025,7 @@ index 2f1ccbfbb0..febc96bfe3 100644
 /* Fake register used by ESP-IDF application to determine whether the code is running on real hardware or on QEMU */
 #define A_SYSCON_ORIGIN_REG     0x3F8
 /* Temporary macro for generating a random value from register SYSCON_RND_DATA_REG */
-@@ -421,12 +446,18 @@ static void esp32c3_machine_init(MachineState *machine)
+@@ -421,12 +448,18 @@ static void esp32c3_machine_init(MachineState *machine)
     object_initialize_child(OBJECT(machine), "efuse", &ms->efuse, TYPE_ESP32C3_EFUSE);
     object_initialize_child(OBJECT(machine), "clock", &ms->clock, TYPE_ESP32C3_CLOCK);
     object_initialize_child(OBJECT(machine), "sha", &ms->sha, TYPE_ESP32C3_SHA);
@@ -768,7 +1044,7 @@ index 2f1ccbfbb0..febc96bfe3 100644
     object_initialize_child(OBJECT(machine), "timg0", &ms->timg[0], TYPE_ESP32C3_TIMG);
     object_initialize_child(OBJECT(machine), "timg1", &ms->timg[1], TYPE_ESP32C3_TIMG);
     object_initialize_child(OBJECT(machine), "systimer", &ms->systimer, TYPE_ESP32C3_SYSTIMER);
-@@ -484,7 +515,9 @@ static void esp32c3_machine_init(MachineState *machine)
+@@ -484,7 +517,9 @@ static void esp32c3_machine_init(MachineState *machine)
 
     /* SPI1 controller (SPI Flash) */
     {
@@ -778,7 +1054,7 @@ index 2f1ccbfbb0..febc96bfe3 100644
         sysbus_realize(SYS_BUS_DEVICE(&ms->spi1), &error_fatal);
         MemoryRegion *mr = sysbus_mmio_get_region(SYS_BUS_DEVICE(&ms->spi1), 0);
         memory_region_add_subregion_overlap(sys_mem, DR_REG_SPI1_BASE, mr, 0);
-@@ -539,7 +572,9 @@ static void esp32c3_machine_init(MachineState *machine)
+@@ -539,7 +574,9 @@ static void esp32c3_machine_init(MachineState *machine)
         if (blk) {
             ms->cache.flash_blk = blk;
         }
@@ -788,7 +1064,7 @@ index 2f1ccbfbb0..febc96bfe3 100644
         sysbus_realize(SYS_BUS_DEVICE(&ms->cache), &error_fatal);
         MemoryRegion *mr = sysbus_mmio_get_region(SYS_BUS_DEVICE(&ms->cache), 0);
         memory_region_add_subregion_overlap(sys_mem, DR_REG_EXTMEM_BASE, mr, 0);
-@@ -635,6 +670,7 @@ static void esp32c3_machine_init(MachineState *machine)
+@@ -635,6 +672,7 @@ static void esp32c3_machine_init(MachineState *machine)
                            qdev_get_gpio_in(intmatrix_dev, ETS_SHA_INTR_SOURCE));
     }
 
@@ -796,7 +1072,7 @@ index 2f1ccbfbb0..febc96bfe3 100644
     /* AES realization */
     {
         ms->aes.parent.gdma = ESP_GDMA(&ms->gdma);
-@@ -654,6 +690,8 @@ static void esp32c3_machine_init(MachineState *machine)
+@@ -654,6 +692,8 @@ static void esp32c3_machine_init(MachineState *machine)
                            qdev_get_gpio_in(intmatrix_dev, ETS_RSA_INTR_SOURCE));
     }
 
@@ -805,7 +1081,7 @@ index 2f1ccbfbb0..febc96bfe3 100644
     /* HMAC realization */
     {
         ms->hmac.parent.efuse = ESP_EFUSE(&ms->efuse);
-@@ -662,6 +700,7 @@ static void esp32c3_machine_init(MachineState *machine)
+@@ -662,6 +702,7 @@ static void esp32c3_machine_init(MachineState *machine)
         memory_region_add_subregion_overlap(sys_mem, DR_REG_HMAC_BASE, mr, 0);
     }
 
@@ -813,7 +1089,7 @@ index 2f1ccbfbb0..febc96bfe3 100644
     /* Digital Signature realization */
     {
         ms->ds.parent.hmac = ESP_HMAC(&ms->hmac);
-@@ -682,6 +721,8 @@ static void esp32c3_machine_init(MachineState *machine)
+@@ -682,6 +723,8 @@ static void esp32c3_machine_init(MachineState *machine)
         memory_region_add_subregion_overlap(sys_mem, DR_REG_AES_XTS_BASE, mr, 0);
     }
 
@@ -822,7 +1098,7 @@ index 2f1ccbfbb0..febc96bfe3 100644
     /* RGB display realization */
     if (!ms->xteink) {
         /* Give the internal RAM memory region to the display */
-@@ -706,6 +747,9 @@ static void xteink_machine_init(MachineState *machine)
+@@ -706,6 +749,9 @@ static void xteink_machine_init(MachineState *machine)
     Esp32C3MachineState *ms = ESP32C3_MACHINE(machine);
     ms->xteink = true;
     esp32c3_machine_init(machine);
@@ -832,6 +1108,33 @@ index 2f1ccbfbb0..febc96bfe3 100644
 
     /* X3 exposes the fingerprint chips; X4 omits them so stock firmware's
      * all-NAK probe selects X4. The X4 panel is a blank protocol stub. */
+diff --git c/hw/riscv/esp32c3_intmatrix.c w/hw/riscv/esp32c3_intmatrix.c
+index c1376b7299..1275808dc0 100644
+--- c/hw/riscv/esp32c3_intmatrix.c
+++ w/hw/riscv/esp32c3_intmatrix.c
+@@ -25,9 +25,10 @@
+ #define INTMATRIX_DEBUG     0
+ #define INTMATRIX_WARNING   0
+ 
+-#define BIT_SET(reg, bit)   ((reg) & BIT(bit))
+-#define CLEAR_BIT(reg, bit) do { (reg) &= ~BIT(bit); } while(0)
+-#define SET_BIT(reg, bit)   do { (reg) |= BIT(bit); } while(0)
+/* 64-bit Shifts For irq_levels - There are up to 62 interrupt sources, so bit ops on the uint64_t level mask must shift in 64-bit. QEMU's BIT() is `1UL << nr`, which is only 32-bit on wasm32 and silently aliases source N to N-32. */
+#define BIT_SET(reg, bit)   ((reg) & (1ULL << (bit)))
+#define CLEAR_BIT(reg, bit) do { (reg) &= ~(1ULL << (bit)); } while(0)
+#define SET_BIT(reg, bit)   do { (reg) |= (1ULL << (bit)); } while(0)
+ 
+ 
+ static int esp32c3_get_output_line_level(ESP32C3IntMatrixState *s, int line)
+@@ -36,7 +37,7 @@ static int esp32c3_get_output_line_level(ESP32C3IntMatrixState *s, int line)
+ 
+     for (int i = 0; level_shared == 0 && i < ESP32C3_INT_MATRIX_INPUTS; i++) {
+         const uint_fast8_t mapped = s->irq_map[i];
+-        if (mapped == line && (s->irq_levels & BIT(i)))
+        if (mapped == line && (s->irq_levels & (1ULL << i)))
+         {
+             level_shared |= 1;
+         }
 diff --git c/include/exec/exec-all.h w/include/exec/exec-all.h
 index 2e4c4cc4b4..99e6da08c9 100644
 --- c/include/exec/exec-all.h
@@ -47,7 +47,7 @@ printf 'Building Emscripten environment (qemu-wasm %s)\n' "$QEMU_WASM_COMMIT"

 FLAGS="-O3 -Wno-error=unused-command-line-argument -matomics -mbulk-memory -DNDEBUG -DG_DISABLE_ASSERT -D_GNU_SOURCE -sASYNCIFY=1 -pthread -sPROXY_TO_PTHREAD=1 -sFORCE_FILESYSTEM -sALLOW_TABLE_GROWTH -sINITIAL_MEMORY=64MB -sALLOW_MEMORY_GROWTH=1 -sMAXIMUM_MEMORY=1GB -sSTACK_SIZE=1048576 -sWASM_BIGINT -sMALLOC=mimalloc -sEXPORT_ES6=1 -sASYNCIFY_IMPORTS=ffi_call_js"

-if [ ! -f build/build.ninja ]; then
+if [ ! -f build/build.ninja ] || ! grep -q 'block/vvfat.c' build/build.ninja; then
    "$ENGINE" run --rm -v "$SRC:/qemu" "$IMAGE" bash -lc "
        cd /qemu
        emconfigure ./configure \\
@@ -59,6 +59,8 @@ if [ ! -f build/build.ninja ]; then
          --without-default-devices \\
          --with-devices-riscv32=xteink \\
          --enable-system \\
+          --enable-qcow1 \\
+          --enable-vvfat \\
          --with-coroutine=fiber \\
          --disable-werror \\
          --disable-docs \\
@@ -1,7 +1,6 @@
 import assert from 'node:assert/strict';
 import { readFile } from 'node:fs/promises';
 import { pathToFileURL } from 'node:url';
-import { gunzipSync } from 'node:zlib';

 const artifactRoot = process.argv[2];
 if (!artifactRoot) {
@@ -10,22 +9,23 @@ if (!artifactRoot) {

 const moduleUrl = pathToFileURL(`${artifactRoot}/qemu-system-riscv32.js`);
 const rom = new Uint8Array(await readFile(`${artifactRoot}/esp32c3-rom.bin`));
-const sdCard = gunzipSync(await readFile('web/assets/blank-sd.img.gz'));
 const { default: createQemu } = await import(moduleUrl);
 const options = {
  arguments: [
    '-S', '-machine', 'xteink,variant=x3', '-accel', 'tcg,tb-size=16', '-L', '/bios',
    '-display', 'none', '-serial', 'null', '-nic', 'none',
    '-drive', 'file=/flash.bin,if=mtd,format=raw',
-    '-drive', 'file=/sd.img,if=sd,format=raw',
+    '-drive', 'file=fat:32:rw:/sdcard,if=sd,format=raw',
  ],
  mainScriptUrlOrBlob: moduleUrl.href,
 };
 options.preRun = [() => {
-  options.FS.mkdir('/bios');
+  options.FS.mkdirTree('/bios');
+  options.FS.mkdirTree('/var/tmp');
+  options.FS.mkdirTree('/sdcard/Test');
  options.FS.writeFile('/bios/esp32c3-rom.bin', rom);
  options.FS.writeFile('/flash.bin', new Uint8Array(16 * 1024 * 1024));
-  options.FS.writeFile('/sd.img', sdCard);
+  options.FS.writeFile('/sdcard/Test/example.txt', 'Lorem ipsum');
 }];

 const module = await createQemu(options);
@@ -35,6 +35,8 @@ const timer = setInterval(() => {
    clearInterval(timer);
    assert.equal(module._xteink_wasm_height(), 792);
    assert.ok(module._xteink_wasm_framebuffer());
+    assert.ok(module.FS.readdir('/sdcard/Test').includes('example.txt'));
+    assert.equal(module.FS.readFile('/sdcard/Test/example.txt', { encoding: 'utf8' }), 'Lorem ipsum');
    module._xteink_wasm_set_adc(1, 2694);
    module._xteink_wasm_set_gpio(3, 0);
    process.exit(0);
@@ -1,6 +1,5 @@
 import assert from 'node:assert/strict';
-import { readFile } from 'node:fs/promises';
-import { BUTTONS, setButton, mergeFirmware, loadEphemeralSdCard } from '../web/app.js';
+import { BUTTONS, DEFAULT_SD_FILES, EXAMPLE_SD_TEXT, formatBytes, setButton, mergeFirmware } from '../web/app.js';

 // Merge - app image is placed at 0x10000 in a 0xFF-erased 16 MB flash with bootloader and partitions.
 const bootloader = new Uint8Array([1, 2, 3]);
@@ -15,14 +14,10 @@ assert.equal(flash[0x10000], 0xe9);
 assert.equal(flash[0x20000], 0xff);
 assert.throws(() => mergeFirmware(new Uint8Array([0x00]), bootloader, partitions), /0xE9/);

-const compressedSd = await readFile('web/assets/blank-sd.img.gz');
-const fetchSd = async () => new Response(compressedSd);
-const firstSd = await loadEphemeralSdCard(import.meta.url, fetchSd);
-const secondSd = await loadEphemeralSdCard(import.meta.url, fetchSd);
-assert.equal(firstSd.length, 64 * 1024 * 1024);
-assert.deepEqual(firstSd.slice(510, 512), new Uint8Array([0x55, 0xaa]));
-firstSd[0] ^= 0xff;
-assert.notEqual(firstSd[0], secondSd[0]);
+assert.equal(DEFAULT_SD_FILES.get('Test/example.txt'), EXAMPLE_SD_TEXT);
+assert.equal(EXAMPLE_SD_TEXT.split('Lorem ipsum').length - 1, 10);
+assert.equal(formatBytes(512), '512 B');
+assert.equal(formatBytes(64 * 1024 * 1024), '64.0 MiB');

 const calls = [];
 const module = {
@@ -38,16 +38,18 @@ async function fetchBin(url) {
  return new Uint8Array(await response.arrayBuffer());
 }

-export async function loadEphemeralSdCard(assetRoot = import.meta.url, fetchFn = fetch) {
-  const response = await fetchFn(new URL('assets/blank-sd.img.gz', assetRoot));
-  if (!response.ok) {
-    throw new Error(`Could not load blank SD card (${response.status}).`);
+const LOREM_IPSUM = 'Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.';
+export const EXAMPLE_SD_TEXT = Array(10).fill(LOREM_IPSUM).join('\n\n');
+export const DEFAULT_SD_FILES = new Map([['Test/example.txt', EXAMPLE_SD_TEXT]]);
+
+function mountEphemeralSdCard(fs) {
+  for (const [path, contents] of DEFAULT_SD_FILES) {
+    const parts = path.split('/');
+    const filename = parts.pop();
+    const directory = `/sdcard/${parts.join('/')}`;
+    fs.mkdirTree(directory);
+    fs.writeFile(`${directory}/${filename}`, contents);
  }
-  if (!response.body || typeof DecompressionStream === 'undefined') {
-    throw new Error('This browser cannot decompress the blank SD card image.');
-  }
-  const stream = response.body.pipeThrough(new DecompressionStream('gzip'));
-  return new Uint8Array(await new Response(stream).arrayBuffer());
 }

 // A full 16 MB image is used as-is; anything else is treated as a CrossPoint app image and merged with the bundled bootloader and partition table.
@@ -170,6 +172,145 @@ let persistLog = false;
 const logBuffer = [];
 const LOG_MAX_LINES = 1000;
 const DEBUG_LOG_KEY = 'xteink-debug-log';
+let activeModule = null;
+
+export function formatBytes(bytes) {
+  if (bytes < 1024) {
+    return `${bytes} B`;
+  }
+  const units = ['KiB', 'MiB', 'GiB'];
+  let value = bytes;
+  let unit = -1;
+  do {
+    value /= 1024;
+    unit++;
+  } while (value >= 1024 && unit < units.length - 1);
+  return `${value.toFixed(value >= 10 ? 1 : 2)} ${units[unit]}`;
+}
+
+function sdEntries(module = activeModule) {
+  if (!module) {
+    return [
+      { path: 'Test/', directory: true },
+      ...[...DEFAULT_SD_FILES].map(([path, contents]) => ({
+        path,
+        size: new TextEncoder().encode(contents).length,
+        read: () => contents,
+      })),
+    ];
+  }
+
+  const entries = [];
+  const visit = (directory, relative = '') => {
+    for (const name of module.FS.readdir(directory).filter(name => name !== '.' && name !== '..').sort()) {
+      const absolute = `${directory}/${name}`;
+      const path = relative ? `${relative}/${name}` : name;
+      const stat = module.FS.stat(absolute);
+      if (module.FS.isDir(stat.mode)) {
+        entries.push({ path: `${path}/`, directory: true });
+        visit(absolute, path);
+      } else {
+        entries.push({
+          path,
+          size: stat.size,
+          read: () => module.FS.readFile(absolute, { encoding: 'utf8' }),
+        });
+      }
+    }
+  };
+  visit('/sdcard');
+  return entries;
+}
+
+function renderFiles() {
+  const list = document.querySelector('#file-list');
+  const preview = document.querySelector('#file-preview');
+  const entries = sdEntries();
+  list.replaceChildren();
+  let firstFile = null;
+
+  for (const entry of entries) {
+    if (entry.directory) {
+      const directory = document.createElement('div');
+      directory.className = 'file-directory';
+      directory.textContent = entry.path;
+      list.append(directory);
+      continue;
+    }
+    const button = document.createElement('button');
+    button.type = 'button';
+    const path = document.createElement('span');
+    path.textContent = entry.path;
+    const size = document.createElement('small');
+    size.textContent = formatBytes(entry.size);
+    button.append(path, size);
+    button.addEventListener('click', () => {
+      try {
+        preview.textContent = entry.read();
+      } catch (error) {
+        preview.textContent = `Could not read ${entry.path}: ${error.message || error}`;
+      }
+    });
+    list.append(button);
+    firstFile ||= button;
+  }
+
+  if (firstFile) {
+    firstFile.click();
+  } else {
+    preview.textContent = 'The SD card is empty.';
+  }
+}
+
+function pathBytes(fs, path) {
+  try {
+    const stat = fs.stat(path);
+    if (!fs.isDir(stat.mode)) {
+      return { bytes: stat.size, files: 1 };
+    }
+    return fs.readdir(path)
+      .filter(name => name !== '.' && name !== '..')
+      .map(name => pathBytes(fs, `${path}/${name}`))
+      .reduce((total, item) => ({ bytes: total.bytes + item.bytes, files: total.files + item.files }), { bytes: 0, files: 0 });
+  } catch {
+    return { bytes: 0, files: 0 };
+  }
+}
+
+function renderDebug() {
+  const jsHeap = performance.memory?.usedJSHeapSize;
+  document.querySelector('#debug-js-heap').textContent = jsHeap ? formatBytes(jsHeap) : 'Unavailable in this browser';
+  if (!activeModule) {
+    return;
+  }
+  const visible = ['/flash.bin', '/bios', '/sdcard', '/var/tmp']
+    .map(path => pathBytes(activeModule.FS, path))
+    .reduce((total, item) => ({ bytes: total.bytes + item.bytes, files: total.files + item.files }), { bytes: 0, files: 0 });
+  const sd = pathBytes(activeModule.FS, '/sdcard');
+  document.querySelector('#debug-wasm-heap').textContent = formatBytes(activeModule.HEAPU8.byteLength);
+  document.querySelector('#debug-memfs').textContent = `${formatBytes(visible.bytes)} in ${visible.files} files`;
+  document.querySelector('#debug-sd-files').textContent = `${formatBytes(sd.bytes)} in ${sd.files} files`;
+}
+
+function initializeInspector() {
+  for (const tab of document.querySelectorAll('[role="tab"]')) {
+    tab.addEventListener('click', () => {
+      for (const candidate of document.querySelectorAll('[role="tab"]')) {
+        const selected = candidate === tab;
+        candidate.setAttribute('aria-selected', selected);
+        document.querySelector(`#${candidate.getAttribute('aria-controls')}`).hidden = !selected;
+      }
+      if (tab.dataset.tab === 'files') {
+        renderFiles();
+      } else if (tab.dataset.tab === 'debug') {
+        renderDebug();
+      }
+    });
+  }
+  renderFiles();
+  renderDebug();
+  setInterval(renderDebug, 1000);
+}

 function logLine(message) {
  logBuffer.push(message);
@@ -188,7 +329,7 @@ function logLine(message) {
  }
 }

-async function boot(file, variant, setStatus, sdCardProvider = loadEphemeralSdCard) {
+async function boot(file, variant, setStatus) {
  if (!crossOriginIsolated) {
    throw new Error('This emulator requires COOP/COEP headers. Start it with `make web`.');
  }
@@ -196,12 +337,11 @@ async function boot(file, variant, setStatus, sdCardProvider = loadEphemeralSdCa

  const artifactRoot = new URL('../dist/wasm/', import.meta.url);
  const qemuUrl = new URL('qemu-system-riscv32.js', artifactRoot);
-  const [firmware, rom, sdCard] = await Promise.all([
+  const [firmware, rom] = await Promise.all([
    prepareFirmware(new Uint8Array(await file.arrayBuffer()), import.meta.url),
    fetchBin(new URL('esp32c3-rom.bin', artifactRoot)),
-    sdCardProvider(import.meta.url),
  ]);
-  const sdMessage = 'Using a blank ephemeral SD card; writes will be discarded when the emulator restarts.';
+  const sdMessage = 'Using a 32 GiB ephemeral directory-backed SD card; writes will be discarded when the emulator restarts.';
  console.log(sdMessage);
  logLine(sdMessage);
  const { default: createQemu } = await import(qemuUrl);
@@ -220,7 +360,7 @@ async function boot(file, variant, setStatus, sdCardProvider = loadEphemeralSdCa
      '-nic', 'none',
      '-d', qemuLogFlags,
      '-drive', 'file=/flash.bin,if=mtd,format=raw',
-      '-drive', 'file=/sd.img,if=sd,format=raw',
+      '-drive', 'file=fat:32:rw:/sdcard,if=sd,format=raw',
    ],
    locateFile: path => new URL(path, artifactRoot).href,
    mainScriptUrlOrBlob: qemuUrl.href,
@@ -229,10 +369,11 @@ async function boot(file, variant, setStatus, sdCardProvider = loadEphemeralSdCa
    stdin: () => null,
  };
  options.preRun = [() => {
-    options.FS.mkdir('/bios');
+    options.FS.mkdirTree('/bios');
+    options.FS.mkdirTree('/var/tmp');
    options.FS.writeFile('/bios/esp32c3-rom.bin', rom);
    options.FS.writeFile('/flash.bin', firmware);
-    options.FS.writeFile('/sd.img', sdCard);
+    mountEphemeralSdCard(options.FS);
  }];

  setStatus('Starting emulator…');
@@ -258,6 +399,7 @@ function initialize() {
    sessionStorage.removeItem(DEBUG_LOG_KEY);
    logEl.textContent = '';
  });
+  initializeInspector();

  const setStatus = (message, error = false) => {
    status.textContent = message;
@@ -270,6 +412,9 @@ function initialize() {
    variantInput.disabled = true;
    try {
      const module = await boot(file, variant, setStatus);
+      activeModule = module;
+      renderFiles();
+      renderDebug();
      if (persistLog) {
        window.__xteinkModule = module;
      }
@@ -49,12 +49,36 @@
      </div>
    </section>

-    <section class="log-panel" aria-label="Emulator logs">
-      <div class="log-header">
-        <span>QEMU log</span>
-        <button id="log-clear" type="button">Clear</button>
+    <section class="inspector" aria-label="Emulator inspector">
+      <div class="tabs" role="tablist" aria-label="Emulator information">
+        <button id="tab-logs" type="button" role="tab" aria-selected="true" aria-controls="panel-logs" data-tab="logs">Logs</button>
+        <button id="tab-files" type="button" role="tab" aria-selected="false" aria-controls="panel-files" data-tab="files">Files</button>
+        <button id="tab-debug" type="button" role="tab" aria-selected="false" aria-controls="panel-debug" data-tab="debug">Debug</button>
+      </div>
+
+      <div id="panel-logs" class="tab-panel" role="tabpanel" aria-labelledby="tab-logs">
+        <div class="log-header">
+          <span>QEMU log</span>
+          <button id="log-clear" type="button">Clear</button>
+        </div>
+        <pre id="log" class="log" role="log" aria-live="polite"></pre>
+      </div>
+
+      <div id="panel-files" class="tab-panel" role="tabpanel" aria-labelledby="tab-files" hidden>
+        <div id="file-list" class="file-list" aria-label="SD card files"></div>
+        <pre id="file-preview" class="file-preview">Select a file to view it.</pre>
+      </div>
+
+      <div id="panel-debug" class="tab-panel" role="tabpanel" aria-labelledby="tab-debug" hidden>
+        <dl class="debug-stats">
+          <div><dt>WASM heap committed</dt><dd id="debug-wasm-heap">Not started</dd></div>
+          <div><dt>Browser JS heap</dt><dd id="debug-js-heap">Unavailable</dd></div>
+          <div><dt>Visible MEMFS files</dt><dd id="debug-memfs">Not started</dd></div>
+          <div><dt>SD files stored</dt><dd id="debug-sd-files">1 file</dd></div>
+          <div><dt>Logical SD capacity</dt><dd>32 GiB</dd></div>
+        </dl>
+        <p class="debug-note">Committed heap is allocated WASM memory, not exact live malloc usage.</p>
      </div>
-      <pre id="log" class="log" role="log" aria-live="polite"></pre>
    </section>
    </div>
  </main>
@@ -71,7 +71,22 @@ canvas { display: block; width: 100%; height: auto; background: #fff; image-rend
  .workspace { grid-template-columns: 1fr; }
 }

-.log-panel { min-width: 0; }
-.log-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: .5rem; font-size: .85rem; color: #b9b3a4; }
+.inspector { min-width: 0; overflow: hidden; border: 1px solid #c8c2b6; border-radius: .75rem; background: #f7f4ed; }
+.tabs { display: grid; grid-template-columns: repeat(3, 1fr); border-bottom: 1px solid #c8c2b6; }
+.tabs button { border: 0; border-right: 1px solid #c8c2b6; border-radius: 0; color: #56534d; background: transparent; }
+.tabs button:last-child { border-right: 0; }
+.tabs button[aria-selected="true"] { color: #fff; background: #343532; }
+.tab-panel { padding: 1rem; }
+.log-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: .5rem; font-size: .85rem; color: #625e55; }
 .log-header button { min-height: auto; padding: .25rem .75rem; font-size: .8rem; }
-.log { margin: 0; max-height: 20rem; overflow: auto; padding: .75rem 1rem; border-radius: .6rem; background: #1c1d1a; color: #d6d0c2; font: .78rem/1.4 ui-monospace, monospace; white-space: pre-wrap; word-break: break-word; }
+.log { margin: 0; max-height: 38rem; overflow: auto; padding: .75rem 1rem; border-radius: .6rem; background: #1c1d1a; color: #d6d0c2; font: .78rem/1.4 ui-monospace, monospace; white-space: pre-wrap; word-break: break-word; }
+.file-list { display: grid; gap: .4rem; margin-bottom: 1rem; }
+.file-directory { padding: .35rem .55rem; color: #625e55; font-weight: 700; }
+.file-list button { display: flex; justify-content: space-between; gap: 1rem; width: 100%; min-height: 2.4rem; text-align: left; }
+.file-list small { color: #cbc5b9; font-weight: 400; }
+.file-preview { min-height: 12rem; max-height: 28rem; overflow: auto; margin: 0; padding: .75rem 1rem; border-radius: .6rem; background: #fff; white-space: pre-wrap; }
+.debug-stats { display: grid; gap: .65rem; margin: 0; }
+.debug-stats div { display: flex; justify-content: space-between; gap: 1rem; padding-bottom: .65rem; border-bottom: 1px solid #d8d2c7; }
+.debug-stats dt { font-weight: 700; }
+.debug-stats dd { margin: 0; text-align: right; }
+.debug-note { margin: 1rem 0 0; color: #625e55; font-size: .8rem; }