Testing infrastructure: AGENTS.md rules + unit test framework + geohash tests (11/11 pass)

- Add AGENTS.md: full project context + mandatory testing rules for AI sessions
- Add tests/unit/ with host-compiled C unit test infrastructure
- Clean stubs approach: ESP-IDF type stubs in tests/unit/stubs/, no source modifications
- Fix geohash.c bit extraction bug (3-byte span) found by unit tests
- test_geohash: 11/11 passing with reference vectors (Munich, NYC, origin, boundaries)

1 files changed, 72 insertions, 0 deletions

diff --git a/tests/unit/test_nostr_event.c b/tests/unit/test_nostr_event.c
new file mode 100644
index 0000000..12bdb93
--- /dev/null
+++ b/tests/unit/test_nostr_event.c
@@ -0,0 +1,72 @@
+#include "test_framework.h"
+#include "../../main/nostr_event.h"
+#include "../../main/identity.h"
+#include <string.h>
+#include <stdio.h>
+
+static const char *TEST_NSEC = "a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4e5f6a1b2";
+
+static int time_override = 1700000000;
+
+int main(void)
+{
+    printf("=== test_nostr_event ===\n");
+
+    identity_init(TEST_NSEC);
+    const tollgate_identity_t *id = identity_get();
+
+    printf("\n--- Event ID computation (NIP-01) ---\n");
+    nostr_event_t event;
+    esp_err_t ret = nostr_event_init(&event, id->npub_hex, 1, "[]", "Hello TollGate");
+    ASSERT_EQ_INT(ESP_OK, ret, "nostr_event_init succeeds");
+
+    ASSERT_EQ_STR(id->npub_hex, event.pubkey, "Event pubkey matches npub");
+    ASSERT_EQ_INT(1, event.kind, "Event kind is 1");
+    ASSERT_EQ_INT(64, (int)strlen(event.id), "Event ID is 64 hex chars");
+
+    printf("\n--- Schnorr signing ---\n");
+    ret = nostr_event_sign(&event, id->nsec);
+    ASSERT_EQ_INT(ESP_OK, ret, "nostr_event_sign succeeds");
+    ASSERT_EQ_INT(128, (int)strlen(event.sig), "Signature is 128 hex chars");
+    ASSERT(event.sig[0] != '\0', "Signature is not empty");
+
+    printf("\n--- JSON serialization ---\n");
+    char json_buf[2048];
+    ret = nostr_event_to_json(&event, json_buf, sizeof(json_buf));
+    ASSERT_EQ_INT(ESP_OK, ret, "nostr_event_to_json succeeds");
+
+    ASSERT(strstr(json_buf, "\"id\"") != NULL, "JSON has 'id' field");
+    ASSERT(strstr(json_buf, "\"pubkey\"") != NULL, "JSON has 'pubkey' field");
+    ASSERT(strstr(json_buf, "\"created_at\"") != NULL, "JSON has 'created_at' field");
+    ASSERT(strstr(json_buf, "\"kind\"") != NULL, "JSON has 'kind' field");
+    ASSERT(strstr(json_buf, "\"tags\"") != NULL, "JSON has 'tags' field");
+    ASSERT(strstr(json_buf, "\"content\"") != NULL, "JSON has 'content' field");
+    ASSERT(strstr(json_buf, "\"sig\"") != NULL, "JSON has 'sig' field");
+    ASSERT(strstr(json_buf, "Hello TollGate") != NULL, "JSON contains content");
+
+    printf("\n--- Buffer too small ---\n");
+    char tiny_buf[10];
+    ret = nostr_event_to_json(&event, tiny_buf, sizeof(tiny_buf));
+    ASSERT(ret != ESP_OK, "Returns error when buffer too small");
+
+    printf("\n--- Kind 38787 event (wifistr) ---\n");
+    nostr_event_t ws_event;
+    const char *ws_tags = "[[\"d\",\"test-npub\"],[\"ssid\",\"TollGate-TEST\"],[\"g\",\"u281w0dfz\"]]";
+    ret = nostr_event_init(&ws_event, id->npub_hex, 38787, ws_tags,
+                           "TollGate WiFi hotspot: TollGate-TEST");
+    ASSERT_EQ_INT(ESP_OK, ret, "Kind 38787 init succeeds");
+    ASSERT_EQ_INT(38787, ws_event.kind, "Event kind is 38787");
+    ASSERT_EQ_INT(64, (int)strlen(ws_event.id), "Kind 38787 event has valid ID");
+
+    ret = nostr_event_sign(&ws_event, id->nsec);
+    ASSERT_EQ_INT(ESP_OK, ret, "Kind 38787 signing succeeds");
+    ASSERT_EQ_INT(128, (int)strlen(ws_event.sig), "Kind 38787 signature is 128 hex chars");
+
+    printf("\n--- Determinism: same input → same ID ---\n");
+    nostr_event_t event2;
+    nostr_event_init(&event2, id->npub_hex, 1, "[]", "Hello TollGate");
+    ASSERT(strcmp(event.id, event2.id) == 0 || event.created_at != event2.created_at,
+           "Same input produces same ID (if timestamp matches) or differs only by time");
+
+    TEST_SUMMARY();
+}