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fix(firmware): get Wi-Fi online — BLE/Wi-Fi mutual exclusion + socket pool sizing #581

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Merged
andymai merged 1 commit into from
May 29, 2026
Merged

fix(firmware): get Wi-Fi online — BLE/Wi-Fi mutual exclusion + socket pool sizing #581

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141 changes: 74 additions & 67 deletions crates/stackchan-firmware/src/main.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1571,76 +1571,83 @@ async fn main(spawner: Spawner) -> ! {
);
}

// BLE peripheral. Shares the same `&'static esp_radio::Controller`
// as Wi-Fi — coex (enabled via the `coex` feature on `esp-radio`)
// schedules airtime between the two stacks. The BLE address +
// local name are derived from the chip's eFuse MAC so a single
// device shows up consistently across reboots, and matches the
// discovery handle visible on the LAN over mDNS.
#[allow(clippy::items_after_statements)]
static BLE_NAME: StaticCell<heapless::String<32>> = StaticCell::new();
let ble_mac = esp_hal::efuse::Efuse::mac_address();
// First, try the operator-supplied name from
// `/sd/DEVICE.NAM` (set via the Hardware Buddy `cmd:name`
// message). Fall back to the MAC-suffixed default. The name
// must start with `Claude` so the Hardware Buddy picker filters
// us in; the default does, and a desktop-set override is
// assumed to as well — we don't enforce the prefix.
let persisted_name = stackchan_firmware::storage::with_storage(
stackchan_firmware::storage::FirmwareStorage::read_device_name,
)
.await
.and_then(|r| match r {
Ok(opt) => opt,
Err(e) => {
defmt::warn!(
"ble: device name read failed ({}); using MAC-suffixed default",
defmt::Debug2Format(&e)
);
None
}
});
let ble_name: &'static str = {
use core::fmt::Write as _;
let mut s: heapless::String<32> = heapless::String::new();
if let Some(name) = persisted_name.as_deref() {
// Cap at heapless::String<32>'s capacity. Operator
// names longer than the BLE GAP 22-byte limit will be
// rejected by the advertise layer; here we just keep
// the buffer write infallible.
let n = name.len().min(32);
if let Err(e) = s.push_str(&name[..n]) {
defmt::panic!("ble: name copy failed: {}", defmt::Debug2Format(&e));
// BLE peripheral — brought up ONLY when no Wi-Fi SSID is configured.
// BLE (Hardware Buddy bridge) and Wi-Fi (HTTP/MCP plane) are mutually
// exclusive: running both needs radio coexistence, whose buffers plus
// BLE's own exhaust the scarce internal-SRAM heap and make the Wi-Fi MAC
// fail to start with `NoMem`. With an SSID present we skip BLE so the
// Wi-Fi stack gets that internal RAM. Address + name derive from the
// eFuse MAC for a stable cross-reboot identity.
if net_config.wifi.ssid.trim().is_empty() {
#[allow(clippy::items_after_statements)]
static BLE_NAME: StaticCell<heapless::String<32>> = StaticCell::new();
let ble_mac = esp_hal::efuse::Efuse::mac_address();
// First, try the operator-supplied name from
// `/sd/DEVICE.NAM` (set via the Hardware Buddy `cmd:name`
// message). Fall back to the MAC-suffixed default. The name
// must start with `Claude` so the Hardware Buddy picker filters
// us in; the default does, and a desktop-set override is
// assumed to as well — we don't enforce the prefix.
let persisted_name = stackchan_firmware::storage::with_storage(
stackchan_firmware::storage::FirmwareStorage::read_device_name,
)
.await
.and_then(|r| match r {
Ok(opt) => opt,
Err(e) => {
defmt::warn!(
"ble: device name read failed ({}); using MAC-suffixed default",
defmt::Debug2Format(&e)
);
None
}
});
let ble_name: &'static str = {
use core::fmt::Write as _;
let mut s: heapless::String<32> = heapless::String::new();
if let Some(name) = persisted_name.as_deref() {
// Cap at heapless::String<32>'s capacity. Operator
// names longer than the BLE GAP 22-byte limit will be
// rejected by the advertise layer; here we just keep
// the buffer write infallible.
let n = name.len().min(32);
if let Err(e) = s.push_str(&name[..n]) {
defmt::panic!("ble: name copy failed: {}", defmt::Debug2Format(&e));
}
} else if let Err(e) = write!(
&mut s,
"Claude stk-{:02x}{:02x}{:02x}",
ble_mac[3], ble_mac[4], ble_mac[5]
) {
defmt::panic!("ble: name format failed: {}", defmt::Debug2Format(&e));
}
} else if let Err(e) = write!(
&mut s,
"Claude stk-{:02x}{:02x}{:02x}",
ble_mac[3], ble_mac[4], ble_mac[5]
BLE_NAME.init(s).as_str()
};
defmt::info!("ble: advertising as {=str}", ble_name);
let ble_connector = match esp_radio::ble::controller::BleConnector::new(
radio,
peripherals.BT,
esp_radio::ble::Config::default(),
) {
defmt::panic!("ble: name format failed: {}", defmt::Debug2Format(&e));
Ok(c) => c,
Err(e) => defmt::panic!(
"ble: BleConnector::new failed ({})",
defmt::Debug2Format(&e)
),
};
let ble_controller: trouble_host::prelude::ExternalController<_, 20> =
trouble_host::prelude::ExternalController::new(ble_connector);
if let Err(e) = spawner.spawn(ble::ble_task(ble::BleTaskConfig {
controller: ble_controller,
address_bytes: ble_mac,
local_name: ble_name,
})) {
defmt::panic!("spawn(ble_task) failed: {}", defmt::Debug2Format(&e));
}
BLE_NAME.init(s).as_str()
};
defmt::info!("ble: advertising as {=str}", ble_name);
let ble_connector = match esp_radio::ble::controller::BleConnector::new(
radio,
peripherals.BT,
esp_radio::ble::Config::default(),
) {
Ok(c) => c,
Err(e) => defmt::panic!(
"ble: BleConnector::new failed ({})",
defmt::Debug2Format(&e)
),
};
let ble_controller: trouble_host::prelude::ExternalController<_, 20> =
trouble_host::prelude::ExternalController::new(ble_connector);
if let Err(e) = spawner.spawn(ble::ble_task(ble::BleTaskConfig {
controller: ble_controller,
address_bytes: ble_mac,
local_name: ble_name,
})) {
defmt::panic!("spawn(ble_task) failed: {}", defmt::Debug2Format(&e));
} else {
defmt::info!(
"ble: skipped — Wi-Fi SSID configured; BLE and Wi-Fi are mutually exclusive to fit internal SRAM"
);
}
Comment on lines +1581 to 1651
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@greptile-apps greptile-apps Bot May 29, 2026

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P2 BLE provisioning → Wi-Fi soft-reconfig still coexists at runtime

The boot-time exclusion correctly prevents the NoMem scenario when an SSID is already in STACKCHAN.RON. However, when a device first boots with no SSID (BLE starts), a Hardware Buddy provisioning write fires WIFI_RECONFIG, and wifi_task calls controller.start_async() while BLE is still running — the same memory-pressure path that caused the original failure. This was broken before this PR too, so no regression is introduced here, but the comment "provisioning over BLE is unaffected" may set a false expectation: BLE advertising/GATT work fine, but the subsequent Wi-Fi bring-up in that flow is still subject to the NoMem constraint until a reboot (or the coex feature is dropped as noted in the follow-ups).

Prompt To Fix With AI 
This is a comment left during a code review.
Path: crates/stackchan-firmware/src/main.rs
Line: 1581-1651

Comment:
**BLE provisioning → Wi-Fi soft-reconfig still coexists at runtime**

The boot-time exclusion correctly prevents the NoMem scenario when an SSID is already in `STACKCHAN.RON`. However, when a device first boots with no SSID (BLE starts), a Hardware Buddy provisioning write fires `WIFI_RECONFIG`, and `wifi_task` calls `controller.start_async()` while BLE is still running — the same memory-pressure path that caused the original failure. This was broken before this PR too, so no regression is introduced here, but the comment "provisioning over BLE is unaffected" may set a false expectation: BLE advertising/GATT work fine, but the subsequent Wi-Fi bring-up in that flow is still subject to the NoMem constraint until a reboot (or the `coex` feature is dropped as noted in the follow-ups).

How can I resolve this? If you propose a fix, please make it concise.

Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!

Fix in Claude Code


if let Err(e) = spawner.spawn(stackchan_firmware::desktop_permission::desktop_permission_task())
Expand Down
14 changes: 10 additions & 4 deletions crates/stackchan-firmware/src/net/stack.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,10 +6,16 @@ use embassy_net::{Runner, StackResources};
use esp_radio::wifi::WifiDevice;
use static_cell::StaticCell;

/// Maximum number of concurrent sockets the firmware ever needs:
/// one for SNTP (UDP), one or two for the HTTP server (listen +
/// accepted), one for mDNS responder, plus a couple of slack.
pub const STACK_SOCKETS: usize = 6;
/// Maximum number of concurrent sockets the firmware ever needs.
///
/// `smoltcp` panics ("adding a socket to a full `SocketSet`") the moment
/// demand exceeds this, so it must cover every consumer that can be live at
/// once: `HTTP_WORKER_COUNT` HTTP listeners (each owns its own socket), plus
/// mDNS, SNTP, the DHCP + DNS clients, and the optional outbound clients
/// (agent sidecar, `VoiceVox`, audio debug). The old value of 6 pre-dated the
/// 4-worker HTTP pool and overflowed as soon as Wi-Fi linked. Slots are cheap
/// static metadata, so over-provisioning costs only a few `.bss` bytes.
pub const STACK_SOCKETS: usize = crate::net::http::HTTP_WORKER_COUNT + 8;

/// Static cell for the embassy-net resource pool. Sized at compile
/// time to avoid heap fragmentation under SNTP/HTTP/mDNS churn.
Expand Down
3 changes: 2 additions & 1 deletion crates/stackchan-firmware/src/storage.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -457,7 +457,8 @@ where
let dst = root
.open_file_in_dir(&short, Mode::ReadWriteCreateOrTruncate)
.map_err(|_| StorageError::Write)?;
dst.write(rendered.as_bytes()).map_err(|_| StorageError::Write)?;
dst.write(rendered.as_bytes())
.map_err(|_| StorageError::Write)?;
dst.flush().map_err(|_| StorageError::Write)?;
}
// Staging served its purpose (a crash-safe copy existed before we
Expand Down
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