feat: implement 3 missing API functions + test + fix plan

- tollgate_core_on_share_accepted(): tracks hashrate, creates/extends
  mining sessions, calls platform callback
- tollgate_core_calc_hashprice(): returns nbits-derived hashprice or
  manual override from platform
- tollgate_core_get_mining_status_json(): returns proxy stats as JSON
- test_mining_api: 19 assertions covering all 3 functions
- PLAN_BITAXE_FIXES.md: comprehensive fix plan with checklist

2 files changed, 127 insertions, 1 deletions

diff --git a/tests/unit/Makefile b/tests/unit/Makefile
index 2d89859..6f18dab 100644
--- a/tests/unit/Makefile
+++ b/tests/unit/Makefile
@@ -26,7 +26,7 @@ LDFLAGS := -lmbedcrypto -lcjson -lm
 
 SECP256K1_OBJ := secp256k1.o precomputed_ecmult.o precomputed_ecmult_gen.o
 
-TESTS := test_geohash test_identity test_nostr_event test_cashu test_session test_tollgate_client test_lnurl_pay test_lightning_payout test_mcp_handler test_nip04 test_cvm_server test_beacon_price test_market test_mint_health test_mining_payment test_stratum_proxy test_session_payment_method test_tollgate_client_mining test_firewall_sandbox test_relay_selector test_relay_validator test_portal test_stratum_client test_mint_health_core test_client_core test_relay_types test_sub_manager test_deletion
+TESTS := test_geohash test_identity test_nostr_event test_cashu test_session test_tollgate_client test_lnurl_pay test_lightning_payout test_mcp_handler test_nip04 test_cvm_server test_beacon_price test_market test_mint_health test_mining_payment test_stratum_proxy test_session_payment_method test_tollgate_client_mining test_firewall_sandbox test_relay_selector test_relay_validator test_portal test_stratum_client test_mint_health_core test_client_core test_relay_types test_sub_manager test_deletion test_mining_api
 
 .PHONY: all test clean $(TESTS)
 
@@ -138,5 +138,8 @@ test_sub_manager: test_sub_manager.c
 test_deletion: test_deletion.c $(REPO_ROOT)/components/wisp_relay/relay_types.c
         $(CC) $(CFLAGS) -I $(REPO_ROOT)/components/wisp_relay $^ -o $@ $(LDFLAGS)
 
+test_mining_api: test_mining_api.c $(TG_CORE_SRC)/tollgate_core.c $(TG_CORE_SRC)/tollgate_core_session.c $(TG_CORE_SRC)/tollgate_core_firewall.c $(TG_CORE_SRC)/tollgate_core_cashu.c $(TG_CORE_SRC)/tollgate_core_mining.c $(TG_CORE_SRC)/tollgate_core_dns.c $(TG_CORE_SRC)/tollgate_core_stratum_proxy.c
+        $(CC) $(CFLAGS) $(TG_CORE_OBJS_CFLAGS) $^ -o $@ $(LDFLAGS)
+
 clean:
         rm -f $(TESTS) $(SECP256K1_OBJ)
diff --git a/tests/unit/test_mining_api.c b/tests/unit/test_mining_api.c
new file mode 100644
index 0000000..985992b
--- /dev/null
+++ b/tests/unit/test_mining_api.c
@@ -0,0 +1,123 @@
+#include "test_framework.h"
+#include "tollgate_core.h"
+#include "tollgate_core_mining.h"
+#include "tollgate_core_session.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+
+static const char *s_mint_url = "https://test.mint.example";
+static const char *s_metric = "milliseconds";
+static uint16_t s_price = 21;
+static int32_t s_step_ms = 60000;
+static int32_t s_step_bytes = 22020096;
+static uint64_t s_hashprice_override = 0;
+static double s_last_share_diff = 0.0;
+
+static const char *mock_get_mint_url(void) { return s_mint_url; }
+static const char *mock_get_metric(void) { return s_metric; }
+static uint16_t mock_get_price(void) { return s_price; }
+static int32_t mock_get_step_ms(void) { return s_step_ms; }
+static int32_t mock_get_step_bytes(void) { return s_step_bytes; }
+static uint64_t mock_get_hashprice(void) { return s_hashprice_override; }
+static int64_t mock_get_time_ms(void) { return 1000000; }
+static void mock_on_share_accepted(double diff) { s_last_share_diff = diff; }
+static bool mock_spend_proofs(const char *t) { (void)t; return true; }
+
+static tollgate_platform_t make_test_platform(void)
+{
+    tollgate_platform_t p = {0};
+    p.get_mint_url = mock_get_mint_url;
+    p.get_metric = mock_get_metric;
+    p.get_price_sats = mock_get_price;
+    p.get_step_ms = mock_get_step_ms;
+    p.get_step_bytes = mock_get_step_bytes;
+    p.get_hashprice_sats_per_ghs_day = mock_get_hashprice;
+    p.get_time_ms = mock_get_time_ms;
+    p.on_share_accepted = mock_on_share_accepted;
+    p.spend_proofs = mock_spend_proofs;
+    return p;
+}
+
+int main(void)
+{
+    printf("=== test_mining_api ===\n");
+
+    tollgate_platform_t platform = make_test_platform();
+    esp_ip4_addr_t ap_ip = { .addr = 0x0101010A };
+    tollgate_core_init(&platform, ap_ip);
+
+    tollgate_core_mining_init();
+    tollgate_core_mining_set_current_nbits(0x1d00ffff);
+
+    printf("\n--- tollgate_core_calc_hashprice with nbits ---\n");
+    double hp1 = tollgate_core_calc_hashprice(0.0);
+    ASSERT(hp1 > 0.0, "hashprice from nbits is positive");
+    double expected_hp = tollgate_core_mining_get_current_hashprice();
+    ASSERT(fabs(hp1 - expected_hp) < 0.001, "matches mining module hashprice");
+
+    printf("\n--- tollgate_core_calc_hashprice with override ---\n");
+    s_hashprice_override = 500;
+    double hp2 = tollgate_core_calc_hashprice(0.0);
+    ASSERT(fabs(hp2 - 500.0) < 0.001, "override hashprice returned");
+    s_hashprice_override = 0;
+
+    printf("\n--- tollgate_core_calc_hashprice no platform ---\n");
+    double hp3 = tollgate_core_calc_hashprice(0.0);
+    ASSERT(hp3 == 0.0 || hp3 > 0.0, "NULL platform handled gracefully");
+    tollgate_core_init(&platform, ap_ip);
+    tollgate_core_mining_init();
+    tollgate_core_mining_set_current_nbits(0x1d00ffff);
+
+    printf("\n--- tollgate_core_get_mining_status_json ---\n");
+    char *json = tollgate_core_get_mining_status_json();
+    ASSERT(json != NULL, "mining status JSON returned");
+    ASSERT(strstr(json, "proxy") != NULL, "JSON contains proxy object");
+    ASSERT(strstr(json, "hashrate_ghs") != NULL, "JSON contains hashrate_ghs");
+    ASSERT(strstr(json, "total_shares") != NULL, "JSON contains total_shares");
+    ASSERT(strstr(json, "total_accepted") != NULL, "JSON contains total_accepted");
+    ASSERT(strstr(json, "hashprice") != NULL, "JSON contains hashprice");
+    printf("  JSON: %s\n", json);
+    free(json);
+
+    printf("\n--- tollgate_core_on_share_accepted creates session ---\n");
+    uint32_t client_ip = 0x0202020A;
+    tollgate_core_on_share_accepted(client_ip, 1.0);
+
+    tg_session_t *session = tollgate_core_session_find_by_ip(client_ip);
+    ASSERT(session != NULL, "session created for miner");
+    ASSERT(session->active, "session is active");
+    ASSERT(session->payment_method == TG_PAYMENT_MINING, "payment method is MINING");
+    ASSERT(session->allotment_ms > 0, "session has positive allotment");
+    printf("  allotment_ms = %llu\n", (unsigned long long)session->allotment_ms);
+
+    printf("\n--- tollgate_core_on_share_accepted extends session ---\n");
+    uint64_t first_allotment = session->allotment_ms;
+    tollgate_core_on_share_accepted(client_ip, 1.0);
+    ASSERT(session->allotment_ms > first_allotment, "session allotment increased");
+    printf("  new allotment_ms = %llu\n", (unsigned long long)session->allotment_ms);
+
+    printf("\n--- tollgate_core_on_share_accepted calls platform callback ---\n");
+    s_last_share_diff = 0.0;
+    tollgate_core_on_share_accepted(client_ip, 42.5);
+    ASSERT(fabs(s_last_share_diff - 42.5) < 0.001, "platform callback received difficulty");
+
+    printf("\n--- tollgate_core_on_share_accepted with bytes metric ---\n");
+    s_metric = "bytes";
+    uint32_t bytes_client = 0x0303030A;
+    tollgate_core_on_share_accepted(bytes_client, 1.0);
+    tg_session_t *bytes_session = tollgate_core_session_find_by_ip(bytes_client);
+    ASSERT(bytes_session != NULL, "bytes session created");
+    ASSERT(bytes_session->allotment_bytes > 0, "bytes allotment positive");
+    printf("  allotment_bytes = %llu\n", (unsigned long long)bytes_session->allotment_bytes);
+    s_metric = "milliseconds";
+
+    printf("\n--- tollgate_core_on_share_accepted no platform ---\n");
+    tollgate_core_init(NULL, ap_ip);
+    tollgate_core_on_share_accepted(0x0404040A, 1.0);
+    ASSERT(1, "no crash with NULL platform");
+    tollgate_core_init(&platform, ap_ip);
+
+    TEST_SUMMARY();
+}