diff --git a/hardware/PCB/.gitignore b/hardware/PCB/.gitignore
index a0acfff..4a2c23a 100644
--- a/hardware/PCB/.gitignore
+++ b/hardware/PCB/.gitignore
@@ -5,3 +5,4 @@
 *-backups/
 *.bak
 __pycache__/
+.history/
diff --git a/src/admin_command_gate.h b/src/admin_command_gate.h
index 26325d8..28cd90d 100644
--- a/src/admin_command_gate.h
+++ b/src/admin_command_gate.h
@@ -9,6 +9,8 @@
 extern "C" {
 #endif
 
+/* Blocking recursive task-context gate. Pair each successful take with a give
+ * on the same task; this does not replace the canonical command dispatcher. */
 esp_err_t admin_command_gate_take(void);
 void admin_command_gate_give(void);
 
diff --git a/src/admin_ssh_console.c b/src/admin_ssh_console.c
index f0e663e..d1e8555 100644
--- a/src/admin_ssh_console.c
+++ b/src/admin_ssh_console.c
@@ -190,6 +190,8 @@ static bool session_is_current(const admin_ssh_console_token_t *token,
     if (owner == NULL) {
         return false;
     }
+    /* Database and transport-owner checks run outside the console spinlock;
+     * neither an open console slot nor an unchanged account alone is sufficient. */
     bool account_current = false;
     bool current = principal->role == USER_ROLE_ADMIN &&
         user_database_principal_is_current(principal, &account_current) == ESP_OK &&
@@ -773,6 +775,8 @@ static void worker_task(void *context)
             continue;
         }
 
+        /* Queue admission is not execution authority: revalidate the remote
+         * principal and reserve its exact slot before invoking a handler. */
         bool current = session_is_current(&request.token, &request.principal);
         bool active;
         taskENTER_CRITICAL(&s_lock);
@@ -877,6 +881,8 @@ static void control_task(void *context)
         if (xQueueReceive(s_control_queue, &request, portMAX_DELAY) != pdTRUE) {
             continue;
         }
+        /* Drain waiting stays off the dispatcher so it cannot stall other
+         * commands; empty application buffers do not prove peer receipt. */
         TickType_t deadline = xTaskGetTickCount() + pdMS_TO_TICKS(10000U);
         bool drained = false;
         while ((int32_t)(xTaskGetTickCount() - deadline) < 0) {
@@ -1127,6 +1133,8 @@ void admin_ssh_console_close(const admin_ssh_console_token_t *token)
             session->prompt_length = 0U;
             wake_prompt = true;
         }
+        /* Invalidate immediately, but retain an executing slot's identity until
+         * the worker returns and wipes it; admission must not reuse it meanwhile. */
         session->active = false;
         if (!session->executing) {
             secure_wipe(session, sizeof(*session));
diff --git a/src/admin_ssh_console.h b/src/admin_ssh_console.h
index c581373..0e1a832 100644
--- a/src/admin_ssh_console.h
+++ b/src/admin_ssh_console.h
@@ -129,6 +129,7 @@ esp_err_t admin_ssh_console_start_uart_frontend(void);
 /* Valid only while a registered command callback runs on the dispatcher task. */
 bool admin_ssh_console_dispatch_is_remote(void);
 bool admin_ssh_console_dispatch_is_web(void);
+/* Borrowed until this command returns; NULL outside remote dispatch. */
 const user_principal_t *admin_ssh_console_dispatch_principal(void);
 /* Revalidate account, originating owner/session and token before side effects.
  * False outside the dispatcher; UART0 dispatch remains physically trusted. */
@@ -146,6 +147,8 @@ void admin_ssh_console_close(const admin_ssh_console_token_t *token);
 
 /* Called by the session owner. Returns false when input must be backpressured. */
 bool admin_ssh_console_accepts_input(const admin_ssh_console_token_t *token);
+/* With valid arguments, consumed is the accepted prefix even on a short feed.
+ * A true result does not imply all bytes were consumed; retain the remainder. */
 bool admin_ssh_console_feed_input(const admin_ssh_console_token_t *token,
                                   const uint8_t *data, size_t length,
                                   size_t *consumed);
diff --git a/src/console_completion.h b/src/console_completion.h
index 72cc0a2..a6326d8 100644
--- a/src/console_completion.h
+++ b/src/console_completion.h
@@ -15,6 +15,7 @@ extern "C" {
 /* Install late-terminal upgrade handling and project-specific completion. */
 void console_completion_install(void);
 
+/* Called synchronously with a borrowed static string; false stops visitation. */
 typedef bool (*console_completion_visitor_t)(const char *candidate, void *context);
 
 /* Visit the same matching hint candidates used by both UART0 and admin SSH. */
diff --git a/src/console_input.h b/src/console_input.h
index 29200a5..b49c58c 100644
--- a/src/console_input.h
+++ b/src/console_input.h
@@ -8,6 +8,10 @@
 
 #include "esp_err.h"
 
+/* Blocking command-handler helpers: remote dispatch uses its session prompt;
+ * otherwise UART0 is read directly, flushing pending input before the prompt.
+ * Capacity includes the trailing NUL; output_length excludes it. Callers own
+ * the output and must wipe secrets after use, including hidden input. */
 esp_err_t console_input_read_hidden(const char *prompt,
                                     uint8_t *output, size_t capacity,
                                     size_t minimum_length, size_t maximum_length,
diff --git a/src/local_boot_animation.h b/src/local_boot_animation.h
index 3756692..5481c96 100644
--- a/src/local_boot_animation.h
+++ b/src/local_boot_animation.h
@@ -5,5 +5,7 @@
 
 #include "esp_err.h"
 
-/* Plays the OLED-only startup identity animation; a missing display is nonfatal. */
+/* Synchronous animation with task delays; call after display start and before
+ * the status renderer. Returns display/frame errors, including an absent panel;
+ * the boot caller must treat these as nonfatal to other services. */
 esp_err_t local_boot_animation_play(void);
diff --git a/src/local_display.c b/src/local_display.c
index a56f584..e7c2a39 100644
--- a/src/local_display.c
+++ b/src/local_display.c
@@ -204,6 +204,7 @@ static esp_err_t flush_dirty_locked(void)
         if (error != ESP_OK) {
             return error;
         }
+        /* Retire only fully transmitted pages; failures leave remaining work dirty. */
         s_dirty_pages &= (uint8_t)~page_mask;
     }
     return ESP_OK;
@@ -324,6 +325,7 @@ static esp_err_t initialize_locked(uint8_t address)
     s_inverted = false;
     memset(s_framebuffer, 0, sizeof(s_framebuffer));
     s_dirty_pages = (uint8_t)((1U << LOCAL_DISPLAY_PAGE_COUNT) - 1U);
+    /* Clear panel RAM before enabling output so startup cannot expose stale pixels. */
     error = flush_dirty_locked();
     if (error == ESP_OK) {
         error = send_command_locked(0xafU);
@@ -543,6 +545,7 @@ esp_err_t local_display_frame_begin(void)
         give_lock();
         return ESP_ERR_INVALID_STATE;
     }
+    /* Keep the mutex across drawing and commit/cancel; only this task may finish. */
     s_frame_active = true;
     s_frame_owner = xTaskGetCurrentTaskHandle();
     return ESP_OK;
@@ -555,6 +558,7 @@ esp_err_t local_display_frame_end(void)
     }
     esp_err_t error = flush_dirty_locked();
     if (error != ESP_OK) {
+        /* A partial frame requires panel reinitialization before further drawing. */
         s_initialized = false;
     }
     set_last_error(error);
@@ -566,6 +570,7 @@ esp_err_t local_display_frame_end(void)
 
 void local_display_frame_cancel(void)
 {
+    /* Cancel releases ownership without I2C; framebuffer edits are not rolled back. */
     if (s_frame_active && s_frame_owner == xTaskGetCurrentTaskHandle()) {
         s_frame_active = false;
         s_frame_owner = NULL;
diff --git a/src/local_display.h b/src/local_display.h
index 50e596d..79e2fe3 100644
--- a/src/local_display.h
+++ b/src/local_display.h
@@ -51,7 +51,10 @@ esp_err_t local_display_stop(void);
 esp_err_t local_display_get_snapshot(local_display_snapshot_t *snapshot);
 esp_err_t local_display_probe_expected(uint8_t *address_7bit);
 
-/* Bounded scan of usable 7-bit addresses 0x08 through 0x77. */
+/* Synchronous scan after bus init; ESP_ERR_NOT_FOUND means no responders.
+ * Callback and responding_count may be NULL. Callbacks run in the caller's
+ * task after releasing the display mutex; context is borrowed only until return.
+ * Scans usable 7-bit addresses 0x08 through 0x77. */
 esp_err_t local_display_scan(local_display_scan_callback_t callback,
                              void *context,
                              size_t *responding_count);
@@ -63,13 +66,16 @@ esp_err_t local_display_set_inverted(bool inverted);
  * A frame holds only the display's own mutex and is owned by the task that
  * begins it. Callers must never retain a service/broker mutex while beginning
  * or ending a frame. Only the owning task may end or cancel it; end sends only
- * modified 8-pixel pages and releases the display mutex on all outcomes.
+ * modified 8-pixel pages and releases the owning task's mutex even on IO error.
+ * A failed flush requires panel restart before another frame can begin.
+ * Cancel releases ownership without IO; framebuffer edits are not rolled back.
  */
 esp_err_t local_display_frame_begin(void);
 esp_err_t local_display_frame_end(void);
 void local_display_frame_cancel(void);
 
-/* Drawing coordinates are panel-local and are clipped to the selected panel. */
+/* Drawing requires a frame owned by the calling task; otherwise it is a no-op.
+ * Coordinates are panel-local and are clipped to the selected panel. */
 void local_display_frame_clear(local_display_panel_t panel);
 void local_display_frame_clear_all(void);
 void local_display_frame_set_pixel(local_display_panel_t panel,
diff --git a/src/local_status_ui.c b/src/local_status_ui.c
index 327361a..01ef223 100644
--- a/src/local_status_ui.c
+++ b/src/local_status_ui.c
@@ -394,6 +394,8 @@ static void draw_content_item(local_status_icon_t icon, uint8_t y, const char *t
 
 static void collect_snapshot(local_status_snapshot_t *snapshot)
 {
+    /* Gather independent service observations before taking the display lock;
+     * this is a render copy, not an atomic snapshot across services. */
     memset(snapshot, 0, sizeof(*snapshot));
 
     snapshot->serial_running = serial_service_is_running();
@@ -863,6 +865,7 @@ static bool render_ui(const local_status_ui_state_t *state,
     if (local_display_frame_begin() != ESP_OK) {
         return false;
     }
+    /* A diagnostic hold may have arrived while frame_begin waited for I2C. */
     if (diagnostic_hold_is_active(xTaskGetTickCount())) {
         local_display_frame_cancel();
         return false;
@@ -1340,6 +1343,7 @@ static void local_status_ui_task(void *context)
             rendered = render_ui(&state, &snapshot);
             last_render = now;
         }
+        /* Allow result feedback, but do not let an unavailable panel block reboot. */
         if (state.restart_pending &&
             (rendered || (now - state.mode_since) >= pdMS_TO_TICKS(2000U))) {
             vTaskDelay(pdMS_TO_TICKS(500U));
@@ -1410,6 +1414,8 @@ esp_err_t local_status_ui_update_settings(local_ui_settings_action_t action,
     portEXIT_CRITICAL(&s_timing_mux);
     if (error != ESP_OK) return error;
 
+    /* The busy reservation spans NVS work without holding the timing spinlock;
+     * reset defaults become visible only after persistence succeeds. */
     bool stored = true;
     if (action == LOCAL_UI_SETTINGS_LOAD) error = local_ui_config_load(&candidate, &stored);
     if (action == LOCAL_UI_SETTINGS_DEFAULTS || action == LOCAL_UI_SETTINGS_RESET)
diff --git a/src/local_status_ui.h b/src/local_status_ui.h
index 464d1e0..8d22ff6 100644
--- a/src/local_status_ui.h
+++ b/src/local_status_ui.h
@@ -13,12 +13,14 @@ extern "C" {
 /*
  * Starts the low-priority status renderer and local recovery controls. The
  * task never becomes a broker client or serial writer. The OLED and buttons
- * are optional, so a missing display is not an error.
+ * are optional, so a missing display is not an error. Copies config before
+ * returning; success reports task creation, not completion of hardware setup.
  */
 esp_err_t local_status_ui_start(const local_ui_config_t *config);
 
 /* Runtime settings are copied atomically and never expose display-frame ownership. */
 esp_err_t local_status_ui_get_config(local_ui_config_t *config);
+/* RAM-only copy; rendering observes the change asynchronously, without NVS IO. */
 esp_err_t local_status_ui_apply_config(const local_ui_config_t *config);
 
 typedef enum {
@@ -33,6 +35,9 @@ esp_err_t local_status_ui_get_settings(local_ui_config_t *config, uint32_t *gene
  * Nonzero stale generations return ESP_ERR_INVALID_STATE; contention returns
  * ESP_ERR_TIMEOUT. Load retains the canonical default fallback. Reset commits
  * defaults before publishing RAM, so a storage failure needs no RAM rollback.
+ * config is required only for APPLY and is copied, never retained. Optional
+ * loaded_defaults is true only after a successful LOAD that fell back to defaults.
+ * DEFAULTS changes RAM only; SAVE persists current RAM; RESET does both.
  * No display IO occurs here; successful RAM changes signal renderer activity. */
 esp_err_t local_status_ui_update_settings(local_ui_settings_action_t action,
     uint32_t expected_generation, const local_ui_config_t *config, bool *loaded_defaults);
diff --git a/src/local_ui_config.h b/src/local_ui_config.h
index c702d7f..54bac5a 100644
--- a/src/local_ui_config.h
+++ b/src/local_ui_config.h
@@ -18,13 +18,18 @@
 
 typedef struct {
     uint32_t version;
-    /* Zero disables the corresponding inactivity transition. */
+    /* Zero disables the corresponding inactivity transition. If both are
+         * enabled, off must be strictly later than dim; each is at most 86400 s. */
     uint32_t dim_timeout_seconds;
     uint32_t off_timeout_seconds;
 } local_ui_config_t;
 
 void local_ui_config_defaults(local_ui_config_t *config);
 esp_err_t local_ui_config_validate(const local_ui_config_t *config);
+/* Both outputs are required. Missing/incompatible data yields ESP_OK with
+ * defaults and used_stored_config=false; other storage errors propagate.
+ * Loading never repairs storage or updates the running UI. */
 esp_err_t local_ui_config_load(local_ui_config_t *config, bool *used_stored_config);
 esp_err_t local_ui_config_save(const local_ui_config_t *config);
+/* Commit defaults to NVS, rather than erase the key; does not change live RAM. */
 esp_err_t local_ui_config_reset_storage(void);
diff --git a/src/local_ui_console.h b/src/local_ui_console.h
index d658710..cd59912 100644
--- a/src/local_ui_console.h
+++ b/src/local_ui_console.h
@@ -1,5 +1,5 @@
 /* SPDX-License-Identifier: GPL-3.0-only */
-/* UART0 administration commands for local UI aging settings. */
+/* Shared administration command registration for local UI aging settings. */
 
 #pragma once
 
diff --git a/src/main.c b/src/main.c
index 91cb528..88977d3 100644
--- a/src/main.c
+++ b/src/main.c
@@ -240,6 +240,7 @@ void app_main(void)
     }
     wifi_config_secure_wipe(&wifi_config, sizeof(wifi_config));
 
+    /* Gate each network listener independently; HTTPS failure must not suppress SSH. */
     if (wifi_error == ESP_OK && web_security_error == ESP_OK &&
         web_runtime_error == ESP_OK) {
         esp_err_t start_error = web_server_start();
@@ -314,6 +315,7 @@ void app_main(void)
     ESP_ERROR_CHECK(admin_ssh_console_register_commands());
     /* Upgrade late UART terminals safely and add nested completion. */
     console_completion_install();
+    /* Admit commands only after the shared registry and completion are ready. */
     ESP_ERROR_CHECK(admin_ssh_console_start_uart_frontend());
 
     ESP_LOGI(TAG, "Shared UART0/SSH administration console ready at %d baud",
diff --git a/src/mdns_config.h b/src/mdns_config.h
index 0a165b6..9d81688 100644
--- a/src/mdns_config.h
+++ b/src/mdns_config.h
@@ -14,16 +14,23 @@
 #define MDNS_CONFIG_NVS_NAMESPACE "mdns_cfg"
 #define MDNS_CONFIG_NVS_BLOB_KEY "config"
 
+/* Fixed NVS blob layout; initialize with defaults before editing fields. */
 typedef struct {
     uint32_t schema_version;
     uint16_t blob_size;
     uint8_t suffix_len;
     uint8_t reserved;
+    /* Nonempty lowercase a-z/0-9/hyphen suffix, with no edge hyphens.
+     * NUL-terminate and zero-pad; excludes the sak- prefix and .local domain. */
     char suffix[MDNS_CONFIG_SUFFIX_MAX_LEN + 1U];
 } mdns_config_t;
 
 void mdns_config_defaults(mdns_config_t *config);
 esp_err_t mdns_config_validate(const mdns_config_t *config);
+/* Both outputs required. Missing/incompatible blobs select MAC-derived defaults
+ * with ESP_OK and used_stored_config=false, without rewriting storage.
+ * MAC/default-generation or other storage failures still propagate. */
 esp_err_t mdns_config_load(mdns_config_t *config, bool *used_stored_config);
 esp_err_t mdns_config_save(const mdns_config_t *config);
+/* Commit MAC-derived defaults; does not change the running mDNS configuration. */
 esp_err_t mdns_config_reset_storage(void);
diff --git a/src/mdns_service.c b/src/mdns_service.c
index 6cfd736..8ac137c 100644
--- a/src/mdns_service.c
+++ b/src/mdns_service.c
@@ -55,6 +55,7 @@ static esp_err_t reconcile_record(const char *type, uint16_t port,
     esp_err_t error = available
         ? mdns_service_add(NULL, type, "_tcp", port, NULL, 0)
         : mdns_service_remove(type, "_tcp");
+    /* Keep failed changes pending for the next owner reconciliation. */
     if (error == ESP_OK) *registered = available;
     return error;
 }
@@ -130,6 +131,8 @@ esp_err_t mdns_service_reconcile(void)
     bool https_available = s_https_available;
     bool ssh_available = s_ssh_available;
     portEXIT_CRITICAL(&s_availability_mux);
+    /* Component calls run outside the availability lock; attempt both records
+     * even after a family/record failure, retaining the first error. */
     esp_err_t https_error = reconcile_record("_https", 443, https_available, &s_https_registered);
     if (error == ESP_OK) error = https_error;
     esp_err_t ssh_error = reconcile_record("_ssh", 22, ssh_available, &s_ssh_registered);
@@ -308,6 +311,8 @@ void mdns_service_stop(void)
     if (s_mutex == NULL) {
         return;
     }
+    /* Retain the responder and records; offline reconciliation disables its
+     * address families instead of tearing down component state. */
     lock_service();
     s_announced = false;
     unlock_service();
@@ -329,6 +334,8 @@ esp_err_t mdns_service_reannounce(void)
     uint32_t generation = s_config_generation;
     unlock_service();
 
+    /* Apply the copied generation, not a newer config staged during the call;
+     * a failed hostname update leaves this generation eligible for retry. */
     esp_err_t error = ESP_OK;
     if (generation != s_applied_generation) {
         char hostname[MDNS_CONFIG_SUFFIX_MAX_LEN + 5U] = {0};
diff --git a/src/mdns_service.h b/src/mdns_service.h
index aacda81..b44b5f1 100644
--- a/src/mdns_service.h
+++ b/src/mdns_service.h
@@ -17,8 +17,11 @@ typedef struct {
     esp_err_t last_error;
 } mdns_service_snapshot_t;
 
+/* One-time RAM initialization: copies config but does not start announcements. */
 esp_err_t mdns_service_init(const mdns_config_t *config);
 esp_err_t mdns_service_get_config(mdns_config_t *config);
+/* Copy into RAM only; no persistence or immediate reannouncement. Queue
+ * wifi_manager_mdns_reannounce() separately to request the network update. */
 esp_err_t mdns_service_set_config(const mdns_config_t *config);
 esp_err_t mdns_service_get_snapshot(mdns_service_snapshot_t *snapshot);
 
diff --git a/src/rs232_port_owner.h b/src/rs232_port_owner.h
index 8817953..46c6028 100644
--- a/src/rs232_port_owner.h
+++ b/src/rs232_port_owner.h
@@ -2,6 +2,8 @@
 
 #include "esp_err.h"
 
+/* Cooperative UART1/MAX3243 arbitration, not a task identity or driver lock.
+ * Owners must perform hardware setup/cleanup themselves while holding a claim. */
 typedef enum {
     RS232_PORT_OWNER_NONE,
     RS232_PORT_OWNER_PHASE0,
@@ -9,9 +11,17 @@ typedef enum {
     RS232_PORT_OWNER_FAULT,
 } rs232_port_owner_t;
 
+/* Initialize once before concurrent use; subsequent operations are task-context. */
 esp_err_t rs232_port_owner_init(void);
+/* Claim PHASE0 or SERVICE only. An occupied port (even by the same owner)
+ * returns ESP_ERR_INVALID_STATE; this does not wait for ownership to become free. */
 esp_err_t rs232_port_claim(rs232_port_owner_t owner);
+/* Release only the matching owner after safe cleanup; no hardware IO is done. */
 esp_err_t rs232_port_release(rs232_port_owner_t owner);
+/* Replace previous_owner only if still current. Unsafe cleanup must leave FAULT
+ * in place until reboot; ordinary owners must not release it as if cleanup passed. */
 void rs232_port_mark_fault(rs232_port_owner_t previous_owner);
+/* Observation only, not a claim; returns FAULT before initialization. */
 rs232_port_owner_t rs232_port_get_owner(void);
+/* Returns a static string; caller must not free it. */
 const char *rs232_port_owner_to_string(rs232_port_owner_t owner);
diff --git a/src/secure_random.c b/src/secure_random.c
index 3964a91..740015e 100644
--- a/src/secure_random.c
+++ b/src/secure_random.c
@@ -82,6 +82,9 @@ esp_err_t secure_random_fill(void *output, size_t length)
     unsigned char *cursor = (unsigned char *)output;
     esp_err_t error = ESP_OK;
 
+    /* Hold ownership across all chunks so DRBG state and the lifetime call
+     * budget advance together. Failure may leave a generated prefix in output;
+     * callers must not use the buffer unless the whole request succeeds. */
     xSemaphoreTake(s_random_mutex, portMAX_DELAY);
     while (length > 0U) {
         /* CTR_DRBG limits each request even though the public API need not. */
@@ -120,6 +123,7 @@ int secure_random_mbedtls(void *context, unsigned char *output, size_t length)
 
 void secure_wipe(void *data, size_t size)
 {
+    /* Volatile stores keep secret erasure from becoming a dead-store removal. */
     volatile uint8_t *byte = (volatile uint8_t *)data;
 
     if (byte == NULL) {
diff --git a/src/secure_random.h b/src/secure_random.h
index 8fa438d..9c47588 100644
--- a/src/secure_random.h
+++ b/src/secure_random.h
@@ -18,7 +18,9 @@ extern "C" {
  */
 esp_err_t secure_random_init(void);
 
-/* Fill output from the already-seeded, mutex-protected device DRBG. */
+/* Fill output from the already-seeded, mutex-protected device DRBG.
+ * Failure may leave a generated prefix; use output only on ESP_OK and wipe
+ * sensitive buffers after use. A zero-length request succeeds without init. */
 esp_err_t secure_random_fill(void *output, size_t length);
 
 /* Mbed TLS-compatible adapter: zero means success, negative means failure. */
diff --git a/src/serial_config.h b/src/serial_config.h
index 1e3a1a5..1888e6d 100644
--- a/src/serial_config.h
+++ b/src/serial_config.h
@@ -71,6 +71,8 @@ const char *serial_config_dtr_behavior_to_string(serial_config_dtr_behavior_t va
 
 /* Storage operations initialize the default NVS partition before use. */
 esp_err_t serial_config_storage_init(void);
+/* Missing or incompatible records return ESP_OK with defaults and false.
+ * Other storage errors propagate; valid output pointers still receive defaults. */
 esp_err_t serial_config_load(serial_config_t *config, bool *used_stored_config);
 esp_err_t serial_config_save(const serial_config_t *config);
 esp_err_t serial_config_reset_storage(void);
diff --git a/src/serial_service.c b/src/serial_service.c
index c8d730a..f637ff7 100644
--- a/src/serial_service.c
+++ b/src/serial_service.c
@@ -284,6 +284,7 @@ static void serial_event_task(void *context)
         poll_modem_state();
     }
 
+    /* Account for software TX abandoned on stop before acknowledging quiescence. */
     size_t discarded = (pending_size - pending_offset) +
                        xStreamBufferBytesAvailable(s_tx_stream);
     if (discarded > 0) {
@@ -431,6 +432,7 @@ static esp_err_t stop_locked(bool restore_static_mode)
         return ESP_OK;
     }
 
+    /* Keep the driver and buffers intact unless the I/O task acknowledges stop. */
     s_stop_requested = true;
     if (xSemaphoreTake(s_task_stopped, pdMS_TO_TICKS(SERIAL_STOP_TIMEOUT_MS)) != pdTRUE) {
         ESP_LOGE(TAG, "UART service task did not quiesce within %d ms", SERIAL_STOP_TIMEOUT_MS);
@@ -561,6 +563,7 @@ esp_err_t serial_service_stop(void)
 
     xSemaphoreTake(s_state_mutex, portMAX_DELAY);
     esp_err_t result = stop_locked(true);
+    /* Diagnostics may reclaim the port only after driver removal and safe GPIO restoration. */
     if (!s_running &&
         !uart_is_driver_installed(RS232_UART_PORT) &&
         rs232_port_get_owner() == RS232_PORT_OWNER_SERVICE) {
@@ -594,6 +597,7 @@ esp_err_t serial_service_apply_config(const serial_config_t *config)
     serial_config_t previous = s_config;
     bool restart = s_running;
 
+    /* Retain port ownership across restart; service buffers are discarded, not broker sessions. */
     esp_err_t result = ESP_OK;
     if (restart) {
         result = stop_locked(false);
@@ -602,6 +606,7 @@ esp_err_t serial_service_apply_config(const serial_config_t *config)
         s_config = *config;
         if (restart) {
             result = start_locked(false);
+            /* Retry the old configuration only while cleanup has not faulted ownership. */
             if (result != ESP_OK &&
                 rs232_port_get_owner() == RS232_PORT_OWNER_SERVICE) {
                 esp_err_t original_error = result;
diff --git a/src/serial_service.h b/src/serial_service.h
index e00f630..fcc57e1 100644
--- a/src/serial_service.h
+++ b/src/serial_service.h
@@ -59,7 +59,9 @@ esp_err_t serial_service_get_snapshot(serial_service_snapshot_t *snapshot);
 /*
  * Access is intentionally nonblocking. The session broker is the sole
  * logical RX consumer and TX producer; calls are serialized internally to
- * satisfy FreeRTOS stream-buffer concurrency rules.
+ * satisfy FreeRTOS stream-buffer concurrency rules. Counts may be short or
+ * zero (including lock contention or a stopped service). write counts bytes
+ * copied into the TX queue, not bytes delivered to the UART or peer.
  */
 size_t serial_service_read(uint8_t *data, size_t size);
 size_t serial_service_write(const uint8_t *data, size_t size);
diff --git a/src/session_broker.c b/src/session_broker.c
index 823ae0d..2bfb8c9 100644
--- a/src/session_broker.c
+++ b/src/session_broker.c
@@ -81,6 +81,7 @@ static session_broker_slot_t *find_slot_locked(session_broker_client_id_t client
         return NULL;
     }
 
+    /* Slot bits locate storage; the full ID also rejects stale connection generations. */
     session_broker_slot_t *slot = &s_slots[slot_index];
     if (!slot->connected || slot->id != client_id) {
         return NULL;
@@ -122,6 +123,7 @@ static void broadcast_event_locked(session_broker_event_type_t type,
             continue;
         }
 
+        /* Notifications are advisory: a full queue must not block ownership changes. */
         if (xQueueSend(slot->events, &event, 0) == pdTRUE) {
             ++slot->counters.events_queued;
             ++s_counters.events_queued;
@@ -483,6 +485,7 @@ static esp_err_t broker_force_writer(session_broker_client_id_t client_id,
     }
 
     xSemaphoreTake(s_mutex, portMAX_DELAY);
+    /* Compare the lease generation and target ID under the same lock as reassignment. */
     if (expected_generation && (expected_generation == UINT32_MAX ||
         expected_generation != s_writer_generation)) {
         xSemaphoreGive(s_mutex);
@@ -641,6 +644,7 @@ esp_err_t session_broker_write(session_broker_client_id_t client_id,
         return ESP_ERR_INVALID_STATE;
     }
 
+    /* Keep authorization and enqueue atomic with respect to writer revocation. */
     size_t queued = serial_service_write(data, size);
     size_t rejected = size - queued;
     slot->counters.tx_accepted_bytes += queued;
diff --git a/src/session_broker.h b/src/session_broker.h
index 1f98799..4514548 100644
--- a/src/session_broker.h
+++ b/src/session_broker.h
@@ -41,6 +41,8 @@ typedef enum {
  * Events contain no pointers, so transports can encode them without lifetime
  * concerns. sequence is broker-global and strictly increases per event.
  * client_id identifies the subject; writer_id is the writer after the event.
+ * Delivery is advisory and can drop on full queues; use snapshots to reconcile
+ * current ownership rather than treating event history as authoritative.
  */
 typedef struct {
     uint64_t sequence;
diff --git a/src/ssh_security.h b/src/ssh_security.h
index aec31ab..25bf7f8 100644
--- a/src/ssh_security.h
+++ b/src/ssh_security.h
@@ -34,7 +34,9 @@ typedef struct {
 /* NVS and secure_random must be ready. Existing malformed material is not replaced. */
 esp_err_t ssh_security_init(ssh_security_load_result_t *load_result);
 
-/* Query with output NULL/capacity zero; the required length is always returned. */
+/* Query with output NULL/capacity zero. When material is ready, returns the
+ * required length even for an undersized buffer; no partial key is copied.
+ * Caller owns the private DER copy: never log it, and wipe it after use. */
 esp_err_t ssh_security_copy_private_key(uint8_t *output, size_t capacity,
                                         size_t *output_length);
 esp_err_t ssh_security_get_metadata(ssh_security_metadata_t *metadata);
diff --git a/src/ssh_transport.c b/src/ssh_transport.c
index 633a137..f12cdde 100644
--- a/src/ssh_transport.c
+++ b/src/ssh_transport.c
@@ -479,6 +479,8 @@ static int authenticate_public_key(ssh_slot_t *slot,
                                : WOLFSSH_USERAUTH_FAILURE;
     }
 
+    /* A stored-key match is not proof of possession; only the result callback
+     * may promote this candidate after signature verification and a currentness check. */
     if (public_key->hasSignature != 0U) {
         slot->pending_principal = principal;
         slot->pending_principal_valid = true;
@@ -598,6 +600,8 @@ static bool cleanup_slot(ssh_slot_t *slot)
     }
     close_socket(&slot->socket_fd);
 
+    /* Keep the slot unavailable until its broker client is retired, even when
+     * network teardown has already completed; failed disconnects are retried. */
     if (slot->broker_client_id != SESSION_BROKER_NO_CLIENT) {
         esp_err_t error = session_broker_disconnect(slot->broker_client_id);
         if (error != ESP_OK && error != ESP_ERR_NOT_FOUND) {
@@ -1029,6 +1033,8 @@ static esp_err_t connect_broker(ssh_slot_t *slot, size_t slot_index)
         return error;
     }
     add_counter(&s_counters.broker_connections, 1U);
+    /* Broker calls do not hold the account lock. Recheck across admission and
+     * writer acquisition, undoing the client if its principal became stale. */
     if (!slot_principal_is_current(slot)) {
         disconnect_failed_admission(slot);
         return ESP_ERR_INVALID_STATE;
@@ -1082,6 +1088,8 @@ static void process_handshake(ssh_slot_t *slot, size_t slot_index)
             return;
         }
 
+        /* Routes are exclusive: an administrative shell gets no serial broker
+         * client, and a serial user never enters the command dispatcher. */
         esp_err_t error;
         if (slot->principal.role == USER_ROLE_USER) {
             error = connect_broker(slot, slot_index);
diff --git a/src/ssh_transport.h b/src/ssh_transport.h
index 58448ae..5d89d7f 100644
--- a/src/ssh_transport.h
+++ b/src/ssh_transport.h
@@ -141,7 +141,9 @@ esp_err_t ssh_transport_replace_host_key(bool reset);
 esp_err_t ssh_transport_get_snapshot(ssh_transport_snapshot_t *snapshot);
 esp_err_t ssh_transport_clear_counters(void);
 
-/* Close one session, one account's sessions, or every transport session. */
+/* Request owner-task closure of one session, an account's sessions, or all
+ * sessions. ESP_OK is not a cleanup barrier; revocation also succeeds when
+ * no matching sessions exist. */
 esp_err_t ssh_transport_disconnect(uint32_t session_id);
 esp_err_t ssh_transport_revoke_user(const uint8_t *username,
                                     size_t username_length);
diff --git a/src/status_led.h b/src/status_led.h
index c3ba028..6756063 100644
--- a/src/status_led.h
+++ b/src/status_led.h
@@ -2,6 +2,7 @@
 
 #include "esp_err.h"
 
+/* Diagnostic indication, not aggregate service health: blue/amber/green/red. */
 typedef enum {
     STATUS_LED_IDLE,
     STATUS_LED_RUNNING,
@@ -9,5 +10,8 @@ typedef enum {
     STATUS_LED_FAIL,
 } status_led_state_t;
 
+/* Create the board's RMT-backed LED once at startup; no deinit API is provided. */
 esp_err_t status_led_init(void);
+/* Requires successful init; refreshes the LED synchronously. Callers serialize
+ * updates: this module provides no mutex or background state arbitration. */
 esp_err_t status_led_set(status_led_state_t state);
diff --git a/src/usb_cdc_transport.c b/src/usb_cdc_transport.c
index 27a95c3..2dfa4d3 100644
--- a/src/usb_cdc_transport.c
+++ b/src/usb_cdc_transport.c
@@ -315,6 +315,7 @@ static void discard_host_input(usb_cdc_pending_buffer_t *pending)
     pending->size = 0U;
     pending->offset = 0U;
 
+    /* Drain rather than reset a stream with a live callback writer; bound refill work. */
     uint8_t data[USB_CDC_IO_CHUNK_SIZE];
     size_t drain_budget = USB_CDC_HOST_RX_STREAM_SIZE;
     while (drain_budget > 0U) {
@@ -498,6 +499,7 @@ static void transport_task(void *context)
     bool service_attempted = false;
     bool connect_attempted = false;
     bool reconciled = false;
+    /* Only this task owns broker mediation and the unaccepted tail in each direction. */
     usb_cdc_pending_buffer_t host_pending = {0};
     usb_cdc_pending_buffer_t usb_pending = {0};
     const TickType_t poll_ticks = milliseconds_to_ticks(USB_CDC_POLL_MS);
@@ -683,6 +685,7 @@ static void reset_uninitialized_state(void)
 
 static esp_err_t cleanup_init_allocations(bool cdc_initialized, bool driver_installed)
 {
+    /* Retire callback producers before freeing the storage they can still access. */
     if (cdc_initialized) {
         esp_err_t error = tinyusb_cdcacm_deinit(TINYUSB_CDC_ACM_0);
         if (error != ESP_OK) {
@@ -835,6 +838,7 @@ static esp_err_t enqueue_control_request(usb_cdc_control_t control)
         return ESP_ERR_INVALID_STATE;
     }
 
+    /* Queue admission is not a lease grant; the owner task resolves current broker state. */
     if (xQueueSend(s_control_queue, &control, 0U) != pdTRUE) {
         add_counter(&s_counters.control_drops, 1U);
         return ESP_ERR_TIMEOUT;
diff --git a/src/usb_cdc_transport.h b/src/usb_cdc_transport.h
index 1a610e7..7597427 100644
--- a/src/usb_cdc_transport.h
+++ b/src/usb_cdc_transport.h
@@ -55,6 +55,7 @@ typedef struct {
     bool rts;
     session_broker_client_id_t broker_client_id;
     bool writer;
+    /* Host-requested diagnostics only; does not configure UART1. */
     usb_cdc_transport_line_coding_t line_coding;
     usb_cdc_transport_counters_t counters;
 } usb_cdc_transport_snapshot_t;
@@ -67,7 +68,8 @@ esp_err_t usb_cdc_transport_init(void);
 
 esp_err_t usb_cdc_transport_get_snapshot(usb_cdc_transport_snapshot_t *snapshot);
 
-/* Requests are asynchronous and execute in the transport task. */
+/* Requests are asynchronous and execute in the transport task.
+ * ESP_OK means queued, not granted/released; inspect a later snapshot. */
 esp_err_t usb_cdc_transport_request_writer(void);
 esp_err_t usb_cdc_transport_release_writer(void);
 
diff --git a/src/user_database.c b/src/user_database.c
index dd96d52..4c2a290 100644
--- a/src/user_database.c
+++ b/src/user_database.c
@@ -480,6 +480,8 @@ static esp_err_t commit_candidate_locked(void)
         }
         nvs_close(handle);
     }
+    /* Publish only committed state; on failure the live database stays intact.
+     * The candidate contains verifiers and is wiped on either outcome. */
     if (error == ESP_OK) {
         secure_wipe(&s_database, sizeof(s_database));
         s_database = *s_candidate;
@@ -776,11 +778,15 @@ esp_err_t user_database_authenticate_password(
         memcpy(salt, user->password_salt, sizeof(salt));
         memcpy(expected_hash, user->password_hash, sizeof(expected_hash));
     } else {
+        /* Invalid or unknown credentials still incur KDF work, without making
+         * a dummy-verifier match eligible to authenticate. */
         memcpy(salt, s_dummy_salt, sizeof(salt));
         memcpy(expected_hash, s_dummy_hash, sizeof(expected_hash));
     }
     xSemaphoreGive(s_mutex);
 
+    /* Run the expensive KDF outside the database lock. A match authorizes only
+     * the same account identity, credential generation and role seen above. */
     esp_err_t error = derive_password(kdf_password, kdf_password_length, salt,
                                       iterations, derived_hash);
     bool matched = error == ESP_OK &&
@@ -836,6 +842,8 @@ esp_err_t user_database_authorize_ssh_public_key(
                 key->blob_length == key_blob_length &&
                 memcmp(key->type, key_type, key_type_length) == 0 &&
                 constant_time_equal(key->blob, key_blob, key_blob_length)) {
+                /* This authorizes the key only; the SSH layer must verify the
+                 * signature before treating the principal as authenticated. */
                 fill_principal(user, USER_AUTH_METHOD_SSH_PUBLIC_KEY, principal);
                 *authorized = true;
                 break;
diff --git a/src/user_database.h b/src/user_database.h
index 0d21692..b061ebe 100644
--- a/src/user_database.h
+++ b/src/user_database.h
@@ -41,6 +41,8 @@ typedef enum {
     USER_DATABASE_LOAD_EMPTY,
 } user_database_load_result_t;
 
+/* Secret-free identity copy, not a permanent authorization grant. Recheck
+ * principal currentness at protected boundaries after account changes. */
 typedef struct {
     uint32_t user_id;
     uint32_t auth_generation;
@@ -50,6 +52,8 @@ typedef struct {
     char username[USER_DATABASE_USERNAME_CAPACITY + 1U];
 } user_principal_t;
 
+/* Caller-owned plaintext secret; keep out of routine status/logs and wipe
+ * the entire structure after the intended credential handoff. */
 typedef struct {
     size_t password_length;
     uint8_t password[USER_DATABASE_PASSWORD_CAPACITY + 1U];
@@ -122,15 +126,21 @@ esp_err_t user_database_set_password_current(const user_database_account_t *expe
  * owns/wipes successful output; failures clear it. Same generator as CLI. */
 esp_err_t user_database_generate_password_value(user_database_generated_password_t *generated);
 
+/* ESP_OK alone is not authentication: require authenticated == true before
+ * using principal. Credential rejection normally returns ESP_OK with false. */
 esp_err_t user_database_authenticate_password(
     const uint8_t *username, size_t username_length,
     const uint8_t *password, size_t password_length,
     user_principal_t *principal, bool *authenticated);
+/* Likewise require authorized == true. This checks key membership only;
+ * the SSH layer must verify proof of private-key possession separately. */
 esp_err_t user_database_authorize_ssh_public_key(
     const uint8_t *username, size_t username_length,
     const uint8_t *key_type, size_t key_type_length,
     const uint8_t *key_blob, size_t key_blob_length,
     user_principal_t *principal, bool *authorized);
+/* Account identity/generation/role check only, not transport-session liveness.
+ * ESP_OK reports a completed check; inspect current for the decision. */
 esp_err_t user_database_principal_is_current(const user_principal_t *principal,
                                              bool *current);
 
diff --git a/src/web_account_settings.h b/src/web_account_settings.h
index 0863bbc..6d6af42 100644
--- a/src/web_account_settings.h
+++ b/src/web_account_settings.h
@@ -3,8 +3,14 @@
 #include <stdint.h>
 #include "esp_http_server.h"
 
-/* One session-bound pending/result slot. Dispatcher execution only; completed
- * results are replaceable, not durable history or an idempotent retry API. */
+/* HTTPD authenticates/admin-checks and copies input; only an ID is queued to
+ * the existing dispatcher. HTTP 202 means admission, not mutation success.
+ * One global pending/result slot; only the original login can read its result
+ * (logging in again as the same account does not recover it). Completed results
+ * are replaceable, not durable history or an idempotent retry API.
+ * Execution rechecks the login and 30-second admission deadline; admitted DB
+ * work may finish after session loss. Pending create/password input also has
+ * periodic expiry; executing input is wiped on return, not by that timer. */
 esp_err_t web_account_settings_handler(httpd_req_t *request);
 void web_account_settings_execute(uint32_t id);
 /* POST /api/settings/accounts/keys: admin cookie + Origin/CSRF, JSON exactly
diff --git a/src/web_broker_settings.h b/src/web_broker_settings.h
index 3a7e856..39c23ff 100644
--- a/src/web_broker_settings.h
+++ b/src/web_broker_settings.h
@@ -3,7 +3,13 @@
 #include <stdint.h>
 #include "esp_http_server.h"
 
-/* Optional admin-only snapshot and login-isolated typed assignment/results. */
+/* HTTPD handlers enforce admin admission; POST also requires Origin/CSRF/JSON.
+ * HTTP 202 admits a copied assignment, not a completed writer transfer. One
+ * global slot stays busy through execution; its replaceable result is visible
+ * only to the original login, not a later login by the same account. */
 esp_err_t web_broker_settings_handler(httpd_req_t *request);
 esp_err_t web_broker_operation_handler(httpd_req_t *request);
+/* Existing dispatcher only. Rechecks login and 30-second admission deadline;
+ * broker compares target ID and lease generation atomically. Expiry is checked
+ * on dequeue, not by a slot-release timer; admitted work is not revoked. */
 void web_broker_settings_execute(uint32_t id);
diff --git a/src/web_console.h b/src/web_console.h
index f0a9874..04df064 100644
--- a/src/web_console.h
+++ b/src/web_console.h
@@ -5,4 +5,6 @@
 
 #include "esp_err.h"
 
+/* Register during console setup, before admitting commands. Registration does
+ * not start HTTPS or require it to be running; recovery must work while offline. */
 esp_err_t web_console_register_commands(void);
diff --git a/src/web_cookie_auth.c b/src/web_cookie_auth.c
index 5c9dbb1..3e8e7ee 100644
--- a/src/web_cookie_auth.c
+++ b/src/web_cookie_auth.c
@@ -177,6 +177,7 @@ static esp_err_t require(httpd_req_t *r, bool mutation, bool upgrade, size_t bod
                          web_session_view_t *view, bool *allowed)
 {
     char canonical[129] = {0}, token[65] = {0}, csrf[65] = {0};
+    /* A denial response can return ESP_OK; only allowed grants admission. */
     *allowed = false;
     memset(view, 0, sizeof(*view));
     if (!web_httpd_headers_valid(r) || !cookies_valid(r) || (!upgrade && strchr(r->uri, '?')) ||
@@ -324,6 +325,8 @@ esp_err_t web_cookie_auth_handler(httpd_req_t *r)
             status = "403 Forbidden"; code = "csrf"; goto deny;
         }
     }
+    /* Consume a matching login challenge before body IO or password work;
+     * later failures require a new challenge rather than permitting replay. */
     bool has_cookie = cookie(r, PRELOGIN_COOKIE, token);
     if (has_cookie && mbedtls_sha256((const uint8_t *)token, 64, digest, 0)) goto deny;
     taskENTER_CRITICAL(&s_lock);
@@ -375,6 +378,7 @@ esp_err_t web_cookie_auth_handler(httpd_req_t *r)
         received += (size_t)count;
     }
     if (received != r->content_len || !web_auth_parse_login(body, received, &credentials)) goto deny;
+    /* Charge the shared attempt budget before entering password verification. */
     now = esp_timer_get_time();
     unsigned attempts;
     int64_t retry;
@@ -415,6 +419,7 @@ esp_err_t web_cookie_auth_handler(httpd_req_t *r)
 deny:
     result = failure(r, status, code);
 cleanup:
+    /* Roll back only this response's new challenge, not a reused/replaced one. */
     if (challenge_published && result != ESP_OK) {
         taskENTER_CRITICAL(&s_lock);
         if (epoch == s_epoch && selected >= 0 &&
diff --git a/src/web_cookie_auth.h b/src/web_cookie_auth.h
index 788ee23..c98a235 100644
--- a/src/web_cookie_auth.h
+++ b/src/web_cookie_auth.h
@@ -12,7 +12,11 @@ typedef struct {
 } web_cookie_auth_snapshot_t;
 void web_cookie_auth_get_snapshot(web_cookie_auth_snapshot_t *snapshot);
 void web_cookie_auth_clear_counters(void);
-/* Sends an error on denial, with allowed=false. View is caller-wiped. */
+/* HTTPD handler context, before body reads/responses; all pointers required.
+ * Admission requires ESP_OK AND allowed=true: a sent denial can return ESP_OK.
+ * mutation selects POST plus CSRF; otherwise GET. mutation/upgrade require Origin.
+ * This variant rejects bodies. Role checks remain with the caller; a successful
+ * view is not a lease for later actions. Wipe the view after use, even on denial. */
 esp_err_t web_cookie_auth_require(httpd_req_t *request, bool mutation,
                                   bool upgrade, web_session_view_t *view,
                                   bool *allowed);
diff --git a/src/web_display_settings.h b/src/web_display_settings.h
index 2516dba..3260ec1 100644
--- a/src/web_display_settings.h
+++ b/src/web_display_settings.h
@@ -3,7 +3,13 @@
 #include <stdint.h>
 #include "esp_http_server.h"
 
-/* Optional admin-only RAM snapshot and typed dispatcher admission/results. */
+/* HTTPD handlers enforce admin admission; POST also requires Origin/CSRF/JSON.
+ * HTTP 202 means queued, not applied or persisted. One global slot stays busy
+ * through execution; completed results are replaceable and readable only by
+ * the original login, not a later login by the same account. */
 esp_err_t web_display_settings_handler(httpd_req_t *request);
 esp_err_t web_display_operation_handler(httpd_req_t *request);
+/* Existing dispatcher only. Rechecks login and 30-second admission deadline;
+ * the UI owner compares the configuration generation before mutation. This is
+ * not a completion timeout: admitted RAM/NVS work can outlive the login. */
 void web_display_settings_execute(uint32_t id);
diff --git a/src/web_firmware_update.c b/src/web_firmware_update.c
index b6d30b4..e918ad0 100644
--- a/src/web_firmware_update.c
+++ b/src/web_firmware_update.c
@@ -133,6 +133,8 @@ esp_err_t web_firmware_update_handler(httpd_req_t *request)
         REJECT("400 Bad Request", "invalid_request");
     if (request->content_len < PREFIX_SIZE)
         REJECT("400 Bad Request", "invalid_firmware");
+    /* Acquire reboot, service and identity exclusion before allocating upload
+     * resources or touching flash; cleanup releases only acquired ownership. */
     if (web_firmware_update_reserve_reboot() != ESP_OK)
         REJECT("503 Service Unavailable", "busy");
     gate_owned = true;
@@ -193,6 +195,8 @@ esp_err_t web_firmware_update_handler(httpd_req_t *request)
     esp_partition_pos_t position = {.offset = target->address, .size = target->size};
     if (esp_image_get_metadata(&position, metadata) != ESP_OK || metadata->image_len != received)
         REJECT("400 Bad Request", "invalid_firmware");
+    /* Streaming may outlive login authority. Reauthorize after validation and
+     * before changing the boot target, even though flash was already written. */
     bool current = false;
     if (web_session_store_check_principal(view.id, &view.principal, &current) != ESP_OK || !current)
         REJECT("401 Unauthorized", "authentication_required");
diff --git a/src/web_firmware_update.h b/src/web_firmware_update.h
index 1dcdec6..3fe0a9b 100644
--- a/src/web_firmware_update.h
+++ b/src/web_firmware_update.h
@@ -4,6 +4,11 @@
 
 #define WEB_FIRMWARE_UPDATE_URI "/api/firmware"
 
+/* Synchronous HTTPD POST handler; enforces admin cookie/Origin/CSRF itself.
+ * Streams a raw application/octet-stream image into the inactive OTA slot and
+ * rechecks session authority before boot selection. ESP_OK can mean a sent error
+ * response, not a committed update. Selection survives a failed success response:
+ * never blindly retry; further uploads require reboot. A sent success schedules it. */
 esp_err_t web_firmware_update_handler(httpd_req_t *request);
 
 /* Atomically exclude uploads until reset. Call immediately before an ordinary
diff --git a/src/web_httpd_adapter.h b/src/web_httpd_adapter.h
index d7aef9e..b8b4781 100644
--- a/src/web_httpd_adapter.h
+++ b/src/web_httpd_adapter.h
@@ -23,6 +23,8 @@ bool web_httpd_unread_body(httpd_req_t *request);
 /* After the final response/lookup: preserve only unread pipelined data on a
  * keepalive connection. Closing requests may discard pending data entirely. */
 void web_httpd_wipe_request(httpd_req_t *request, bool closing);
+/* Caller must complete authorization/admission first; this only validates the
+ * handshake, sends 101 and installs the frame callback on success. HTTPD-owner only. */
 esp_err_t web_httpd_upgrade(httpd_req_t *request,
                             esp_err_t (*handler)(httpd_req_t *));
 
diff --git a/src/web_lifecycle_settings.h b/src/web_lifecycle_settings.h
index d6f84e9..babcb3a 100644
--- a/src/web_lifecycle_settings.h
+++ b/src/web_lifecycle_settings.h
@@ -3,9 +3,19 @@
 #include <stdint.h>
 #include "esp_http_server.h"
 
+/* HTTPD handlers enforce admin admission; POST also requires Origin/CSRF/JSON.
+ * One global slot remains reserved through execution. HTTP 202 is not completion:
+ * only successful response send followed by HTTPD handoff can queue the ID;
+ * send success does not prove peer receipt. Handoff has a two-second deadline,
+ * and execution rechecks the original login and 30-second admission deadline.
+ * Results are replaceable and original-login-only, never recoverable by logging
+ * in again. Stop/restart may invalidate that login; lost responses or failed
+ * results do not prove absence of side effects. Do not automatically retry. */
 esp_err_t web_lifecycle_settings_handler(httpd_req_t *request);
 esp_err_t web_lifecycle_operation_handler(httpd_req_t *request);
 /* Existing dispatcher only; callbacks submit IDs, never execute lifecycle work. */
 void web_lifecycle_settings_execute(uint32_t id);
-/* Only after successful HTTPD destruction, before another server can start. */
+/* Only after successful HTTPD destruction, before another server can start.
+ * server is an identity for comparison, not dereferenced here. Retires its ACK
+ * handoff and cancels pending work; executing work retains its slot. */
 void web_lifecycle_settings_stopped(httpd_handle_t server);
diff --git a/src/web_login_ui.h b/src/web_login_ui.h
index 062c2ce..59af786 100644
--- a/src/web_login_ui.h
+++ b/src/web_login_ui.h
@@ -5,5 +5,7 @@
 #include "esp_http_server.h"
 
 /* Standalone public login document. Rendering only: authentication, route
- * registration and bounded challenge allocation belong to web_cookie_auth. */
+ * registration and bounded challenge allocation belong to web_cookie_auth.
+ * Call with a live HTTPD request; sends synchronously without retaining it.
+ * Success reports response submission, not a successful login. */
 esp_err_t web_login_ui_send_response(httpd_req_t *request);
diff --git a/src/web_network_settings.h b/src/web_network_settings.h
index 507cfc9..4e7be93 100644
--- a/src/web_network_settings.h
+++ b/src/web_network_settings.h
@@ -15,6 +15,8 @@
  * ID enters the existing dispatcher. A periodic one-second ESP timer wipes and
  * cancels non-executing input at 30 seconds plus scheduling latency. Executing
  * locals wipe on return; already-admitted work can finish after session loss.
+ * HTTP 202 means dispatcher admission, not the final operation result. Polling
+ * is restricted to the original login; logging in again cannot recover it.
  * 'accepted' means RAM/owner queue admission, NEVER association or DHCP success.
  *
  * SSID JSON is a BYTE string: raw printable ASCII, standard single-character
@@ -31,4 +33,5 @@
  */
 esp_err_t web_network_snapshot_handler(httpd_req_t *request);
 esp_err_t web_network_operation_handler(httpd_req_t *request);
+/* Existing admin dispatcher only; no request pointer survives HTTPD admission. */
 void web_network_settings_execute(uint32_t id);
diff --git a/src/web_security.h b/src/web_security.h
index 688451f..33e6748 100644
--- a/src/web_security.h
+++ b/src/web_security.h
@@ -59,6 +59,9 @@ esp_err_t web_security_init(web_security_load_result_t *load_result);
 /*
  * Query with both outputs NULL/capacities zero. Certificate and key are copied
  * under one lock so a concurrent rotation can never produce a mismatched pair.
+ * Both length pointers are required; ready material reports required lengths even
+ * on INVALID_SIZE, without copying either buffer. Caller owns the copies and
+ * must wipe private-key storage after its consumer has finished with it.
  */
 esp_err_t web_security_copy_tls_material(
     uint8_t *certificate, size_t certificate_capacity,
diff --git a/src/web_serial_settings.h b/src/web_serial_settings.h
index 8ac12c6..0a0d7de 100644
--- a/src/web_serial_settings.h
+++ b/src/web_serial_settings.h
@@ -7,6 +7,8 @@
  * One global slot rejects mutations while pending (including execution). GET
  * exposes only the caller's session result; a later admitted operation replaces
  * that result, so this is not a durable history or an idempotent retry API.
+ * A new login by the same account cannot retrieve it. HTTP 202 means queued,
+ * not applied/persisted; response loss does not cancel an admitted operation.
  * The 30-second deadline is checked when dequeued, not a completion deadline or
  * a timer that frees the slot. Revocation/expiry cancels before operation
  * admission; admitted serial/NVS work may finish after the session is gone. */
diff --git a/src/web_serial_transport.c b/src/web_serial_transport.c
index 0c1dfa8..b17d3cc 100644
--- a/src/web_serial_transport.c
+++ b/src/web_serial_transport.c
@@ -709,6 +709,8 @@ static esp_err_t connect_websocket(httpd_req_t *request, int socket_fd,
         goto cleanup;
     }
 
+    /* Broker creation ran outside the slot lock; recheck authority before
+     * requesting a writer lease and retire the unpublished client on failure. */
     principal_current = false;
     result = identity_is_current(&principal, web_session_id, &principal_current);
     if (result != ESP_OK || !principal_current) {
@@ -1011,6 +1013,8 @@ static void web_serial_send_work(void *argument)
     bool retired = false;
 
     taskENTER_CRITICAL(&s_lock);
+    /* Retire canceled work only when it still owns this slot incarnation;
+     * an old callback must not clear another session's pending frame. */
     bool owned_work = slot->work_pending && work == &slot->work &&
                       work->generation == slot->generation &&
                       work->server == slot->server &&
@@ -1047,6 +1051,8 @@ static void web_serial_send_work(void *argument)
     esp_err_t result = ESP_FAIL;
     int64_t send_start = 0, send_end = 0;
     bool send_called = false;
+    /* In HTTPD context, verify socket ownership as well as the captured slot
+     * generation before sending: a file descriptor alone is reusable. */
     void *current_context = httpd_sess_get_ctx(server, socket_fd);
     if (current_context == slot &&
         httpd_ws_get_fd_info(server, socket_fd) ==
@@ -1149,6 +1155,8 @@ static esp_err_t queue_slot_frame(web_serial_slot_t *slot, uint32_t generation,
     esp_err_t result = httpd_queue_work(server, web_serial_send_work,
                                         &slot->work);
 #endif
+    /* Failed submission has no callback to release the frame; close only
+     * this session rather than retrying data already drained from the broker. */
     if (result != ESP_OK) {
         taskENTER_CRITICAL(&s_lock);
         if (slot->work_pending && slot->generation == generation) {
diff --git a/src/web_serial_transport.h b/src/web_serial_transport.h
index 96a1c11..64c909a 100644
--- a/src/web_serial_transport.h
+++ b/src/web_serial_transport.h
@@ -132,6 +132,8 @@ esp_err_t web_serial_transport_session_ws_handler(httpd_req_t *request,
  * cleanup. Safe to repeat after either store or transport slot reuse. */
 esp_err_t web_serial_transport_revoke_web_session(web_session_id_t id);
 
+/* Copied transport state only: principal_valid marks an active slot, not a fresh
+ * database/session check; writer is cached, not an authoritative broker lease. */
 esp_err_t web_serial_transport_get_snapshot(
     web_serial_transport_snapshot_t *snapshot);
 
diff --git a/src/web_server.c b/src/web_server.c
index c9d25c4..83daee0 100644
--- a/src/web_server.c
+++ b/src/web_server.c
@@ -663,6 +663,7 @@ static esp_err_t start_server(bool reserved)
         xSemaphoreGive(s_server_mutex);
         return ESP_ERR_INVALID_STATE;
     }
+    /* Reserve lifecycle ownership before releasing the mutex for slow startup. */
     s_transitioning = true;
     if (s_generation != UINT32_MAX) ++s_generation;
     serial_transport_ready = s_serial_transport_initialized;
@@ -833,6 +834,7 @@ static esp_err_t stop_server(uint32_t expected_generation, bool restart, bool re
     mdns_service_set_https_available(false);
     xSemaphoreGive(s_server_mutex);
 
+    /* Revoke admission first; teardown failures must not leave usable logins. */
     web_cookie_auth_stop();
     esp_err_t idle_error = web_httpd_idle_detach(server);
     if (idle_error != ESP_OK) {
@@ -924,6 +926,7 @@ esp_err_t web_server_replace_identity(uint32_t expected_service_generation,
         error = web_security_replace_reserved(token);
     }
     if (error == ESP_OK) {
+        /* Report identity commit independently of the subsequent restart result. */
         *committed = true;
         if (running) error = stop_server(0, true, true);
         else if (reset) error = start_server(true);
diff --git a/src/web_session_store.c b/src/web_session_store.c
index a1c7318..197c08e 100644
--- a/src/web_session_store.c
+++ b/src/web_session_store.c
@@ -134,6 +134,8 @@ esp_err_t web_session_store_init(void)
     uint64_t epoch = s_state.epoch;
     taskEXIT_CRITICAL(&s_lock);
 
+    /* Probe RNG outside the lock; the epoch check prevents a concurrent stop
+     * from being undone when initialization returns. */
     uint8_t probe[WEB_SESSION_STORE_SECRET_BYTES] = {0};
     esp_err_t error = secure_random_fill(probe, sizeof(probe));
     secure_wipe(probe, sizeof(probe));
@@ -296,6 +298,8 @@ esp_err_t web_session_store_issue(
                 duplicate = true;
             }
         }
+        /* Publish only into free capacity under the captured revocation epoch;
+         * never evict a live login or recycle an exhausted session identity. */
         if (!s_state.ready || epoch != s_state.epoch ||
             s_state.next_id == UINT64_MAX || now < 0 ||
             now > INT64_MAX - WEB_SESSION_STORE_LIFETIME_US) {
@@ -358,6 +362,8 @@ esp_err_t web_session_store_lookup(
             }
         }
         taskEXIT_CRITICAL(&s_lock);
+        /* Digest matching identifies a candidate, not admission: resolve must
+         * still enforce expiry, store readiness and current account authority. */
         error = resolve(id, view, NULL);
     }
     secure_wipe(token_hash, sizeof(token_hash));
diff --git a/src/web_session_store.h b/src/web_session_store.h
index 3753cb2..45c52be 100644
--- a/src/web_session_store.h
+++ b/src/web_session_store.h
@@ -52,13 +52,18 @@ void web_session_store_stop(void);
 esp_err_t web_session_store_issue(
     const user_principal_t *principal, const char *origin, size_t origin_length,
     char token[WEB_SESSION_STORE_TOKEN_LENGTH + 1U], web_session_view_t *view);
+/* Exact lowercase-hex token span and the same canonical origin used at issue.
+ * Does not refresh the absolute expiry. Clears view on failure; caller wipes it
+ * after success. NOT_FOUND covers absent, expired or stale/mismatched sessions. */
 esp_err_t web_session_store_lookup(
     const char *token, size_t token_length, const char *origin,
     size_t origin_length, web_session_view_t *view);
 
 /* Trusted transport identity check, not a replacement for HTTP cookie/origin
  * authorization. Every successful lookup/check revalidates the principal.
- * No API result is a lease: recheck at later sensitive boundaries. */
+ * No API result is a lease: recheck at later sensitive boundaries.
+ * current is required and set false on failure; ESP_OK means true. NOT_FOUND
+ * means no current match; store/database errors also deny authority. */
 esp_err_t web_session_store_is_current(web_session_id_t id, bool *current);
 /* Also verifies that the transport's copied principal belongs to this ID. */
 esp_err_t web_session_store_check_principal(web_session_id_t id,
diff --git a/src/web_ssh_settings.h b/src/web_ssh_settings.h
index e9316fb..4d019e3 100644
--- a/src/web_ssh_settings.h
+++ b/src/web_ssh_settings.h
@@ -3,7 +3,13 @@
 #include <stdint.h>
 #include "esp_http_server.h"
 
-/* Optional admin-only SSH status and login-isolated ordinary controls. */
+/* HTTPD handlers enforce admin admission; POST also requires Origin/CSRF/JSON.
+ * HTTP 202 means queued, not completed. One global slot stays busy through
+ * execution; its replaceable result belongs to the original login, not the
+ * account across logins. A lost response is not grounds for automatic retry. */
 esp_err_t web_ssh_settings_handler(httpd_req_t *request);
 esp_err_t web_ssh_operation_handler(httpd_req_t *request);
+/* Existing dispatcher only. Rechecks login and 30-second admission deadline
+ * before generation-checked owner calls; admitted work may outlive the login.
+ * Rotation failure does not imply that the new identity was not committed. */
 void web_ssh_settings_execute(uint32_t id);
diff --git a/src/web_ui.h b/src/web_ui.h
index 62f17eb..496e0b8 100644
--- a/src/web_ui.h
+++ b/src/web_ui.h
@@ -22,6 +22,9 @@ typedef enum {
 /*
  * Send one UI resource after the caller has authenticated the request.
  * This module deliberately performs no authentication or URI dispatch.
+ * Call within the HTTPD handler: the request is borrowed only for this
+ * synchronous send; resource storage remains module-owned. Send success does
+ * not establish a browser session or confirm that the browser loaded the UI.
  */
 esp_err_t web_ui_send_response(httpd_req_t *request,
                                web_ui_resource_t resource);
diff --git a/src/wifi_config.h b/src/wifi_config.h
index 0a54d7a..6f70eee 100644
--- a/src/wifi_config.h
+++ b/src/wifi_config.h
@@ -5,6 +5,8 @@
  * The public structures below are also the version-1 NVS wire format. Keep
  * every field fixed-width and introduce a new schema version for layout
  * changes; do not silently reinterpret an existing blob.
+ * Config copies contain plaintext PSKs: never use them for routine status/logs,
+ * and wipe transient copies with wifi_config_secure_wipe() when finished.
  */
 
 #pragma once
@@ -77,6 +79,7 @@ typedef struct {
     uint8_t ap_channel;
     uint8_t reserved[5];
 
+    /* As for station profiles, lengths are authoritative; no NUL is required. */
     uint8_t ap_ssid[WIFI_CONFIG_SSID_MAX_LEN];
     uint8_t ap_psk[WIFI_CONFIG_PSK_MAX_LEN];
     uint8_t reserved_tail[1];
diff --git a/src/wifi_console.h b/src/wifi_console.h
index cef6730..5eb3d6a 100644
--- a/src/wifi_console.h
+++ b/src/wifi_console.h
@@ -4,5 +4,6 @@
 
 #include "esp_err.h"
 
-/* Register Wi-Fi configuration, lifecycle, and diagnostic commands on UART0. */
+/* Register Wi-Fi configuration, lifecycle, and diagnostics in the shared
+ * administration registry; frontend policy controls remote command access. */
 esp_err_t wifi_console_register_commands(void);
diff --git a/src/wifi_manager.c b/src/wifi_manager.c
index abcaaf6..0d8b9b8 100644
--- a/src/wifi_manager.c
+++ b/src/wifi_manager.c
@@ -547,6 +547,7 @@ static void schedule_cycle_retry(manager_runtime_t *runtime)
         }
     }
 
+    /* Back off between whole profile cycles, after attempting fallback AP recovery. */
     uint32_t delay_seconds = runtime->next_backoff_seconds;
     if (delay_seconds < WIFI_MANAGER_INITIAL_BACKOFF_SECONDS) {
         delay_seconds = WIFI_MANAGER_INITIAL_BACKOFF_SECONDS;
@@ -582,6 +583,8 @@ static void start_next_profile(manager_runtime_t *runtime)
     wifi_app_config_t config;
     copy_working_config(&config);
 
+    /* Immediate setup failures advance here; an accepted connect hands progress
+     * to events and the attempt deadline before another profile is configured. */
     while (runtime->next_profile < runtime->profile_count) {
         uint8_t slot = runtime->profile_order[runtime->next_profile++];
         const wifi_config_sta_profile_t *profile = &config.profiles[slot];
@@ -644,6 +647,8 @@ static void start_next_profile_after_current(manager_runtime_t *runtime)
             break;
         }
     }
+    /* Rotate the cycle rather than omit the current profile: it becomes the
+     * final candidate if every alternative fails. */
     for (uint8_t index = 0U; index < count; ++index) {
         uint8_t source = found_active ? (uint8_t)((active_index + 1U + index) % count)
                                       : index;
@@ -1301,6 +1306,8 @@ static void handle_expired_deadlines(manager_runtime_t *runtime)
 static void manager_task(void *context)
 {
     (void)context;
+    /* Event callbacks and command callers feed the queue; policy deadlines and
+     * transition bookkeeping remain private to this task. */
     manager_runtime_t runtime;
     memset(&runtime, 0, sizeof(runtime));
     runtime.next_backoff_seconds = WIFI_MANAGER_INITIAL_BACKOFF_SECONDS;
diff --git a/src/wifi_manager.h b/src/wifi_manager.h
index fe9bc92..050ddf5 100644
--- a/src/wifi_manager.h
+++ b/src/wifi_manager.h
@@ -94,13 +94,15 @@ typedef struct {
  */
 esp_err_t wifi_manager_init(const wifi_app_config_t *config);
 
-/* Returns a copy of the RAM working configuration, including credentials. */
+/* Returns a caller-owned copy of the RAM configuration, including plaintext
+ * credentials. Do not log it; wipe the copy on every exit path after use. */
 esp_err_t wifi_manager_get_working_config(wifi_app_config_t *config);
 
 /*
  * Replaces the RAM working configuration. Disabled-profile-only edits do not
  * interrupt a running radio; changes to effective station/AP policy are
- * applied asynchronously by restarting with the newest generation.
+ * applied asynchronously by restarting with the newest generation. Input is
+ * copied, not retained; success is not radio readiness and does not persist NVS.
  */
 esp_err_t wifi_manager_apply_working_config(const wifi_app_config_t *config);
 
@@ -150,7 +152,10 @@ esp_err_t wifi_manager_save_current(uint32_t generation);
 /* Stored-only load: never generates or installs unknown default credentials. */
 esp_err_t wifi_manager_load_current(uint32_t generation);
 
-/* Lifecycle requests are asynchronous and serialized by the manager task. */
+/* Lifecycle requests are asynchronous and serialized by the manager task.
+ * ESP_OK means queue admission, not completion; observe runtime via snapshots.
+ * Queue-full returns ESP_ERR_TIMEOUT. Accepted start/stop also set the RAM
+ * enabled_at_boot flag to 1/0 respectively; persistence still requires save. */
 esp_err_t wifi_manager_start(void);
 esp_err_t wifi_manager_stop(void);
 esp_err_t wifi_manager_reconnect(void);