Update library usage documentation

- Added BUILD_DIR=/home/teknari/Sync/Programming/VibeCoding/nostr_core_lib to capture absolute build directory
- Changed relative paths to absolute paths in archive extraction
- Fixes 'No such file or directory' error when build.sh is called from customer Makefiles
- Maintains backward compatibility for all existing use cases

LIBRARY_USAGE.md

@@ -88,6 +88,59 @@ Simply include the source files directly in your project:
    gcc your_project.c -lnostr_core -lm
    ```
 
+## Building the Library
+
+### Using the Provided Build Script
+
+The library includes an automated build script that handles all dependencies and creates a self-contained static library.
+
+**IMPORTANT**: The build script must be run from within the `nostr_core_lib` directory:
+
+```bash
+# Correct usage:
+cd nostr_core_lib
+./build.sh
+
+# If you need to use it from your project directory:
+cd nostr_core_lib
+./build.sh
+cd ..
+gcc your_app.c nostr_core_lib/libnostr_core_x64.a -lz -ldl -lpthread -lm -o your_app
+```
+
+**Common Error**: Running `./nostr_core_lib/build.sh` from outside the library directory will fail with:
+```
+[ERROR] Build script must be run from the nostr_core_lib directory
+```
+
+### Build Script Options
+
+```bash
+# Auto-detect NIPs from your source code
+./build.sh
+
+# Force specific NIPs
+./build.sh --nips=1,6,19
+
+# Build all available NIPs
+./build.sh --nips=all
+
+# Build for specific architecture
+./build.sh arm64
+
+# Build with tests
+./build.sh --tests
+
+# Get help
+./build.sh --help
+```
+
+The build script automatically:
+- Scans your `.c` files for `#include "nip*.h"` statements
+- Compiles only the needed NIPs
+- Creates a self-contained static library (`libnostr_core_x64.a`)
+- Includes all dependencies (OpenSSL, curl, secp256k1, cJSON)
+
 ## Basic Usage Example
 
 ```c

build.sh

@@ -146,6 +146,27 @@ if [ "$HELP" = true ]; then
 fi
 
 print_info "NOSTR Core Library - Customer Build Script"
+
+# Check if we're running from the correct directory
+if [ ! -d "nostr_core" ] || [ ! -f "nostr_core/utils.c" ] || [ ! -d "secp256k1" ]; then
+    print_error "Build script must be run from the nostr_core_lib directory"
+    echo ""
+    echo "It looks like you're trying to run this script from your project directory."
+    echo "Please change to the nostr_core_lib directory first, then run the build script."
+    echo ""
+    echo "Correct usage:"
+    echo "  cd nostr_core_lib"
+    echo "  ./build.sh"
+    echo ""
+    echo "Or if nostr_core_lib is in your project directory:"
+    echo "  cd nostr_core_lib"
+    echo "  ./build.sh"
+    echo "  cd .."
+    echo "  gcc your_app.c nostr_core_lib/libnostr_core_x64.a -lz -ldl -lpthread -lm -o your_app"
+    echo ""
+    exit 1
+fi
+
 print_info "Auto-detecting needed NIPs from your source code..."
 
 
@@ -367,6 +388,9 @@ done
 ###########################################################################################
 print_info "Creating self-contained static library: $OUTPUT"
 
+# Store the build directory to ensure correct paths when extracting from subdirectories
+BUILD_DIR=$(pwd)
+
 # Create temporary directories for extracting objects
 TMP_SECP256K1=".tmp_secp256k1_$$"
 TMP_OPENSSL=".tmp_openssl_$$"
@@ -379,21 +403,21 @@ if [ -f "$SECP256K1_LIB" ]; then
     if [ "$VERBOSE" = true ]; then
         print_info "Extracting secp256k1 objects..."
     fi
-    (cd "$TMP_SECP256K1" && ar x "../$SECP256K1_LIB")
+    (cd "$TMP_SECP256K1" && ar x "$BUILD_DIR/$SECP256K1_LIB")
 fi
 
 # Extract OpenSSL objects
 if [ "$VERBOSE" = true ]; then
     print_info "Extracting OpenSSL objects..."
 fi
-(cd "$TMP_OPENSSL" && ar x "../openssl-install/lib64/libssl.a")
-(cd "$TMP_OPENSSL" && ar x "../openssl-install/lib64/libcrypto.a")
+(cd "$TMP_OPENSSL" && ar x "$BUILD_DIR/openssl-install/lib64/libssl.a")
+(cd "$TMP_OPENSSL" && ar x "$BUILD_DIR/openssl-install/lib64/libcrypto.a")
 
 # Extract curl objects
 if [ "$VERBOSE" = true ]; then
     print_info "Extracting curl objects..."
 fi
-(cd "$TMP_CURL" && ar x "../curl-install/lib/libcurl.a")
+(cd "$TMP_CURL" && ar x "$BUILD_DIR/curl-install/lib/libcurl.a")
 
 # Combine all objects into final library
 if [ "$VERBOSE" = true ]; then