diff --git a/Makefile b/Makefile
index e384fb8..6a767aa 100644
--- a/Makefile
+++ b/Makefile
@@ -5,7 +5,7 @@ BUILD_DIR := build
 
 EXAMPLES := hello fibonacci factorial structs enums methods algebraic_enums generics generics_struct generic_infer generic_infer2 extend_generic pattern_matching strings strings2 map result_option try_operator ownership ownership_checked drop_early_return lifetime_elision ctfe async concurrency os_time process json iter trait_bounds channel sync jwt stdlib_ergonomics tuples func_ptr map_remove array_iter_extra string_extra multi_closure iter_hof closure_control match_let string_interp iter_generic generic_infer_hof struct_tuple_pat match_block nested_patterns match_guards pattern_shadow
 
-.PHONY: all build dev debug test clean clean-all test-examples selfhost test-golden test-errors test-stdlib selfhost-loop lsp fmt-check docs
+.PHONY: all build dev debug test clean clean-all test-examples selfhost test-golden test-errors test-stdlib selfhost-loop lsp fmt-check docs bench test-apps test-dwarf
 
 all: build
 
@@ -193,6 +193,32 @@ test-lsp: lsp
 
 .PHONY: test-registry
 test-registry: build
-	@echo "=== Registry smoke (E.1) ==="
+	@echo "=== Registry smoke (E.1 + HTTP) ==="
 	@chmod +x tools/smoke_registry.sh
 	@tools/smoke_registry.sh
+
+# E.2 — build showcase apps + simpledb/jwt CLI smoke
+.PHONY: test-apps
+test-apps: build
+	@echo "=== Apps smoke (E.2) ==="
+	@chmod +x tools/smoke_apps.sh
+	@tools/smoke_apps.sh
+
+# E.5 — micro-benchmarks (Bux + C/Nim/Zig twins)
+.PHONY: bench
+bench: build
+	@chmod +x tools/bench.sh
+	@tools/bench.sh
+
+# E.5 — Nexus HTTP throughput (wrk); optional via BENCH_NEXUS=1 make bench
+.PHONY: bench-nexus
+bench-nexus: build
+	@chmod +x tools/bench_nexus.sh
+	@tools/bench_nexus.sh
+
+# E.4 — DWARF / #line debugger smoke
+.PHONY: test-dwarf
+test-dwarf: build
+	@echo "=== DWARF / #line smoke (E.4) ==="
+	@chmod +x tools/smoke_dwarf.sh
+	@tools/smoke_dwarf.sh
diff --git a/apps/nexus/README.md b/apps/nexus/README.md
index 260f994..53ff0a7 100644
--- a/apps/nexus/README.md
+++ b/apps/nexus/README.md
@@ -32,9 +32,12 @@ cd apps/nexus
 
 # Run
 ./nexus
+
+# Optional env (also used by `make bench-nexus`)
+# NEXUS_PORT=18080 NEXUS_BIND=127.0.0.1 NEXUS_WORKERS=4 ./build/nexus
 ```
 
-Server starts on `http://0.0.0.0:8080`:
+Server starts on `http://0.0.0.0:8080` (override with `NEXUS_PORT` / `NEXUS_BIND`):
 
 ```
 ╔══════════════════════════════════════════════╗
diff --git a/apps/nexus/src/Main.bux b/apps/nexus/src/Main.bux
index a59bf0b..e3d7cb7 100644
--- a/apps/nexus/src/Main.bux
+++ b/apps/nexus/src/Main.bux
@@ -5,6 +5,8 @@ module Main {
     import Router::{Handler, Route, Router};
     import Server::{RunServer};
     import Std::Array::{Array, Array_New, Array_Push};
+    import Std::Os::{Os_GetEnv};
+    import Std::String::{String_Len, String_ToInt};
 
     func BuildRouter() -> Router {
         var routes: Array<Route> = Array_New<Route>(8);
@@ -39,8 +41,36 @@ module Main {
         };
     }
 
+    /// Apply optional env overrides for benches / ops:
+    ///   NEXUS_PORT, NEXUS_WORKERS, NEXUS_BIND, NEXUS_PUBLIC
+    func ApplyEnvConfig(config: *ServerConfig) {
+        let portEnv: String = Os_GetEnv("NEXUS_PORT");
+        if String_Len(portEnv) > 0 {
+            let p: int64 = String_ToInt(portEnv);
+            if p > 0 && p < 65536 {
+                config.port = p as int;
+            }
+        }
+        let workersEnv: String = Os_GetEnv("NEXUS_WORKERS");
+        if String_Len(workersEnv) > 0 {
+            let w: int64 = String_ToInt(workersEnv);
+            if w > 0 && w <= 256 {
+                config.workerCount = w as int;
+            }
+        }
+        let bindEnv: String = Os_GetEnv("NEXUS_BIND");
+        if String_Len(bindEnv) > 0 {
+            config.bindAddr = bindEnv;
+        }
+        let pubEnv: String = Os_GetEnv("NEXUS_PUBLIC");
+        if String_Len(pubEnv) > 0 {
+            config.publicDir = pubEnv;
+        }
+    }
+
     func Main() -> int {
-        let config: ServerConfig = DefaultConfig();
+        var config: ServerConfig = DefaultConfig();
+        ApplyEnvConfig(&config);
         let router: Router = BuildRouter();
 
         return RunServer(config, router);
diff --git a/apps/simpledb/README.md b/apps/simpledb/README.md
index 1940405..c52a057 100644
--- a/apps/simpledb/README.md
+++ b/apps/simpledb/README.md
@@ -50,10 +50,9 @@ Data is stored as plain text, one `key=value` per line. The file is created auto
 ## Build
 
 ```sh
-# workaround: disable broken JWT module
-mv ../../lib/crypto/jwt.bux ../../lib/crypto/jwt.bux.bak
+cd apps/simpledb
 ../../buxc build
-mv ../../lib/crypto/jwt.bux.bak ../../lib/crypto/jwt.bux
+./build/simpledb data.db set hello world
 ```
 
 ## API
diff --git a/benches/README.md b/benches/README.md
new file mode 100644
index 0000000..8a00372
--- /dev/null
+++ b/benches/README.md
@@ -0,0 +1,56 @@
+# Bux benchmarks (E.5)
+
+Micro-kernels + optional Nexus HTTP throughput for regression and language comparison.
+
+## Quick run
+
+```bash
+# From repo root
+make bench              # Bux micro + C + Nim (+ Zig if installed)
+make bench-nexus        # wrk vs apps/nexus /api/health
+BENCH_NEXUS=1 make bench
+```
+
+## Micro suites
+
+| Suite | Kernels | Build |
+|-------|---------|-------|
+| `micro/` | Bux: `int_loop`, `fib30`, `string_concat`, `array_push` | `buxc build` |
+| `c/` | C: `fib30`, `int_loop` | `gcc -O2` |
+| `nim/` | Nim twins | `nim c -d:release --opt:speed` |
+| `zig/` | Zig twins (optional) | `zig build-exe -OReleaseFast` |
+
+Output lines:
+
+```
+BENCH <name> iters=N total_us=T us_per_op=P
+```
+
+## Nexus throughput
+
+`tools/bench_nexus.sh` / `make bench-nexus`:
+
+1. Builds `apps/nexus`
+2. Starts on `NEXUS_PORT` (default **18080**), bind `127.0.0.1`
+3. `wrk -t4 -c64 -d5s` against `/api/health`
+4. Prints `BENCH nexus_health rps=…`
+
+Env knobs:
+
+| Variable | Default | Meaning |
+|----------|---------|---------|
+| `NEXUS_PORT` | `18080` | Listen port (also used by the server binary) |
+| `NEXUS_WORKERS` | `4` | Worker threads |
+| `NEXUS_BENCH_DURATION` | `5s` | wrk `-d` |
+| `NEXUS_BENCH_C` | `64` | wrk connections |
+| `NEXUS_BENCH_T` | `4` | wrk threads |
+
+Server-side (any nexus run):
+
+- `NEXUS_PORT`, `NEXUS_WORKERS`, `NEXUS_BIND`, `NEXUS_PUBLIC`
+
+## Notes
+
+- Numbers vary by machine; use them relatively (same host, same day).
+- Nexus currently closes connections (`Connection: close`) — RPS is honest for that model, not keep-alive maxed.
+- Requires `wrk` for `bench-nexus` (`apt install wrk` on Debian/Ubuntu).
diff --git a/benches/c/fib.c b/benches/c/fib.c
new file mode 100644
index 0000000..294ae1e
--- /dev/null
+++ b/benches/c/fib.c
@@ -0,0 +1,26 @@
+/* C reference: recursive fib(30) — compare with benches/micro fib30 */
+#include <stdio.h>
+#include <stdint.h>
+#include <time.h>
+
+static int fib(int n) {
+    if (n <= 1) return n;
+    return fib(n - 1) + fib(n - 2);
+}
+
+static int64_t now_us(void) {
+    struct timespec ts;
+    clock_gettime(CLOCK_MONOTONIC, &ts);
+    return (int64_t)ts.tv_sec * 1000000LL + (int64_t)ts.tv_nsec / 1000LL;
+}
+
+int main(void) {
+    (void)fib(20); /* warmup */
+    int64_t t0 = now_us();
+    int r = fib(30);
+    int64_t t1 = now_us();
+    if (r < 0) return 1;
+    printf("BENCH fib30 iters=1 total_us=%lld us_per_op=%lld\n",
+           (long long)(t1 - t0), (long long)(t1 - t0));
+    return 0;
+}
diff --git a/benches/c/int_loop.c b/benches/c/int_loop.c
new file mode 100644
index 0000000..cb8b071
--- /dev/null
+++ b/benches/c/int_loop.c
@@ -0,0 +1,24 @@
+/* C reference: 1e6 integer arithmetic loop */
+#include <stdio.h>
+#include <stdint.h>
+#include <time.h>
+
+static int64_t now_us(void) {
+    struct timespec ts;
+    clock_gettime(CLOCK_MONOTONIC, &ts);
+    return (int64_t)ts.tv_sec * 1000000LL + (int64_t)ts.tv_nsec / 1000LL;
+}
+
+int main(void) {
+    const int iters = 1000000;
+    int acc = 0;
+    int64_t t0 = now_us();
+    for (int i = 0; i < iters; i++) {
+        acc = acc + i * 3 - 1;
+    }
+    int64_t t1 = now_us();
+    if (acc == 0 && iters > 0) return 1;
+    printf("BENCH int_loop iters=%d total_us=%lld us_per_op=%lld\n",
+           iters, (long long)(t1 - t0), (long long)((t1 - t0) / iters));
+    return 0;
+}
diff --git a/benches/micro/bux.toml b/benches/micro/bux.toml
new file mode 100644
index 0000000..30d091a
--- /dev/null
+++ b/benches/micro/bux.toml
@@ -0,0 +1,8 @@
+[Package]
+Name    = "micro"
+Version = "0.1.0"
+Type    = "bin"
+Description = "Micro-benchmarks for Bux (E.5)"
+
+[Build]
+Output = "Bin"
diff --git a/benches/micro/src/Main.bux b/benches/micro/src/Main.bux
new file mode 100644
index 0000000..3f09b2d
--- /dev/null
+++ b/benches/micro/src/Main.bux
@@ -0,0 +1,104 @@
+// Micro-benchmarks (E.5) — recursive fib, string concat, array push.
+// Prints lines: BENCH name iters total_us us_per_op
+import Std::Io::{PrintLine, Print};
+import Std::Time::{Time_NowUs};
+import Std::String::{String_FromInt, String_Concat, String_Len};
+import Std::Array::{Array, Array_New, Array_Push, Array_Len, Array_Get};
+
+func Fib(n: int) -> int {
+    if n <= 1 {
+        return n;
+    }
+    return Fib(n - 1) + Fib(n - 2);
+}
+
+func Report(name: String, iters: int, usTotal: int64) {
+    var perOpUs: int64 = 0;
+    if iters > 0 {
+        perOpUs = usTotal / (iters as int64);
+    }
+    Print("BENCH ");
+    Print(name);
+    Print(" iters=");
+    Print(String_FromInt(iters as int64));
+    Print(" total_us=");
+    Print(String_FromInt(usTotal));
+    Print(" us_per_op=");
+    PrintLine(String_FromInt(perOpUs));
+}
+
+func BenchIntLoop() {
+    let iters: int = 1000000;
+    var acc: int = 0;
+    var i: int = 0;
+    let t0: int64 = Time_NowUs();
+    while i < iters {
+        acc = acc + i * 3 - 1;
+        i = i + 1;
+    }
+    let t1: int64 = Time_NowUs();
+    if acc == 0 && iters > 0 {
+        PrintLine("unreachable");
+    }
+    Report("int_loop", iters, t1 - t0);
+}
+
+func BenchFib() {
+    discard Fib(20);
+    let n: int = 30;
+    let t0: int64 = Time_NowUs();
+    let r: int = Fib(n);
+    let t1: int64 = Time_NowUs();
+    if r < 0 {
+        PrintLine("unreachable");
+    }
+    Report("fib30", 1, t1 - t0);
+}
+
+func BenchStringConcat() {
+    let iters: int = 50000;
+    var i: int = 0;
+    let t0: int64 = Time_NowUs();
+    var s: String = "";
+    while i < iters {
+        s = String_Concat(s, "x");
+        if String_Len(s) > 256 {
+            s = "x";
+        }
+        i = i + 1;
+    }
+    let t1: int64 = Time_NowUs();
+    if String_Len(s) < 0 {
+        PrintLine("unreachable");
+    }
+    Report("string_concat", iters, t1 - t0);
+}
+
+func BenchArrayPush() {
+    let iters: int = 100000;
+    var arr: Array<int> = Array_New<int>(16);
+    var i: int = 0;
+    let t0: int64 = Time_NowUs();
+    while i < iters {
+        Array_Push<int>(&arr, i);
+        i = i + 1;
+    }
+    let t1: int64 = Time_NowUs();
+    let n: uint = Array_Len<int>(&arr);
+    if n as int != iters {
+        Print("array len mismatch: ");
+        PrintLine(String_FromInt(n as int64));
+    }
+    discard Array_Get<int>(&arr, (iters - 1) as uint);
+    Report("array_push", iters, t1 - t0);
+}
+
+func Main() -> int {
+    PrintLine("=== Bux micro-benchmarks (E.5) ===");
+    BenchIntLoop();
+    BenchFib();
+    BenchStringConcat();
+    BenchArrayPush();
+    PrintLine("=== done ===");
+    return 0;
+}
diff --git a/benches/nim/fib.nim b/benches/nim/fib.nim
new file mode 100644
index 0000000..917c39c
--- /dev/null
+++ b/benches/nim/fib.nim
@@ -0,0 +1,16 @@
+## Nim twin of benches/c/fib.c — recursive fib(30)
+import std/[times, strformat]
+
+proc fib(n: int): int =
+  if n <= 1: return n
+  fib(n - 1) + fib(n - 2)
+
+proc nowUs(): int64 =
+  int64(epochTime() * 1_000_000.0)
+
+discard fib(20)
+let t0 = nowUs()
+let r = fib(30)
+let t1 = nowUs()
+if r < 0: quit(1)
+echo &"BENCH fib30 iters=1 total_us={t1 - t0} us_per_op={t1 - t0}"
diff --git a/benches/nim/int_loop.nim b/benches/nim/int_loop.nim
new file mode 100644
index 0000000..fd10fa5
--- /dev/null
+++ b/benches/nim/int_loop.nim
@@ -0,0 +1,15 @@
+## Nim twin of benches/c/int_loop.c — 1e6 integer arithmetic loop
+import std/[times, strformat]
+
+proc nowUs(): int64 =
+  int64(epochTime() * 1_000_000.0)
+
+const iters = 1_000_000
+var acc = 0
+let t0 = nowUs()
+for i in 0 ..< iters:
+  acc = acc + i * 3 - 1
+let t1 = nowUs()
+if acc == 0 and iters > 0: quit(1)
+let total = t1 - t0
+echo &"BENCH int_loop iters={iters} total_us={total} us_per_op={total div iters}"
diff --git a/benches/zig/fib.zig b/benches/zig/fib.zig
new file mode 100644
index 0000000..ac562a8
--- /dev/null
+++ b/benches/zig/fib.zig
@@ -0,0 +1,22 @@
+// Zig twin of benches/c/fib.c — recursive fib(30)
+// Build: zig build-exe -OReleaseFast -femit-bin=build/fib fib.zig
+const std = @import("std");
+
+fn fib(n: i32) i32 {
+    if (n <= 1) return n;
+    return fib(n - 1) + fib(n - 2);
+}
+
+fn nowUs() i64 {
+    return @divTrunc(@as(i64, @intCast(std.time.nanoTimestamp())), 1000);
+}
+
+pub fn main() !void {
+    _ = fib(20);
+    const t0 = nowUs();
+    const r = fib(30);
+    const t1 = nowUs();
+    if (r < 0) return error.Unreachable;
+    const out = std.io.getStdOut().writer();
+    try out.print("BENCH fib30 iters=1 total_us={d} us_per_op={d}\n", .{ t1 - t0, t1 - t0 });
+}
diff --git a/benches/zig/int_loop.zig b/benches/zig/int_loop.zig
new file mode 100644
index 0000000..dc6051b
--- /dev/null
+++ b/benches/zig/int_loop.zig
@@ -0,0 +1,22 @@
+// Zig twin of benches/c/int_loop.c — 1e6 integer arithmetic loop
+// Build: zig build-exe -OReleaseFast -femit-bin=build/int_loop int_loop.zig
+const std = @import("std");
+
+fn nowUs() i64 {
+    return @divTrunc(@as(i64, @intCast(std.time.nanoTimestamp())), 1000);
+}
+
+pub fn main() !void {
+    const iters: i32 = 1_000_000;
+    var acc: i32 = 0;
+    const t0 = nowUs();
+    var i: i32 = 0;
+    while (i < iters) : (i += 1) {
+        acc = acc + i * 3 - 1;
+    }
+    const t1 = nowUs();
+    if (acc == 0 and iters > 0) return error.Unreachable;
+    const total = t1 - t0;
+    const out = std.io.getStdOut().writer();
+    try out.print("BENCH int_loop iters={d} total_us={d} us_per_op={d}\n", .{ iters, total, @divTrunc(total, iters) });
+}
diff --git a/bootstrap/cli.nim b/bootstrap/cli.nim
index fec0ff4..851d061 100644
--- a/bootstrap/cli.nim
+++ b/bootstrap/cli.nim
@@ -15,6 +15,7 @@ type
     color*: ColorMode
     quiet*: bool
     verbose*: bool
+    release*: bool   ## --release: -O2, no -g / no #line (E.4 dual)
 
 proc printUsage*() =
   echo """Bux Programming Language (bootstrap compiler)
@@ -42,15 +43,22 @@ Command options:
   fmt  --check        Exit 1 if any file would be reformatted (CI)
   doc  --out <file>   Write docs to file (default: stdout)
   add  --path / --git Explicit source; else resolve via registry
+  build --release     Optimized build (-O2, no debug / #line)
+
+Registry:
+  BUX_REGISTRY            Local path or http(s):// URL to registry.toml
+  BUX_REGISTRY_REFRESH=1  Force re-download of HTTP index cache
+  BUX_CFLAGS              Extra flags appended to the C compiler line
 
 Global options:
   --color <auto|on|off>   Control colored output (default: auto)
   -q, --quiet             Suppress non-error output
   -v, --verbose           Verbose output
+  --release               Optimize (-O2), omit -g and #line maps
 """
 
 proc parseGlobalOptions(args: seq[string]): tuple[opts: GlobalOptions, rest: seq[string], ok: bool] =
-  result.opts = GlobalOptions(color: cmAuto, quiet: false, verbose: false)
+  result.opts = GlobalOptions(color: cmAuto, quiet: false, verbose: false, release: false)
   result.rest = @[]
   result.ok = true
   var i = 0
@@ -74,6 +82,8 @@ proc parseGlobalOptions(args: seq[string]): tuple[opts: GlobalOptions, rest: seq
       result.opts.quiet = true
     elif arg == "-v" or arg == "--verbose":
       result.opts.verbose = true
+    elif arg == "--release":
+      result.opts.release = true
     else:
       result.rest.add(arg)
     inc i
@@ -411,10 +421,14 @@ proc cmdAdd*(args: seq[string], opts: GlobalOptions): int =
   elif gitUrl.len > 0:
     depLine = &"{depName} = {{ Version = \"{version}\", Source = \"{gitUrl}\" }}"
   else:
-    # Registry resolve (E.1)
+    # Registry resolve (E.1 + HTTP URL)
     let reg = loadRegistry()
     if reg.path.len == 0:
-      printError("no package registry found (set BUX_REGISTRY or install config/registry.toml)", useColor)
+      if reg.sourceUrl.len > 0:
+        printError(&"failed to fetch registry from {reg.sourceUrl}", useColor)
+        printError("hint: check network, curl/wget, or set BUX_REGISTRY to a local file", useColor)
+      else:
+        printError("no package registry found (set BUX_REGISTRY or install config/registry.toml)", useColor)
       return 1
     let pkg = registryLookup(reg, depName, version)
     if pkg.name.len == 0:
@@ -423,7 +437,8 @@ proc cmdAdd*(args: seq[string], opts: GlobalOptions): int =
       return 1
     depLine = formatRegistryDepLine(depName, pkg)
     if not opts.quiet:
-      printInfo(&"Resolved '{depName}' {pkg.version} from registry {reg.path}", useColor)
+      let src = if reg.sourceUrl.len > 0: reg.sourceUrl else: reg.path
+      printInfo(&"Resolved '{depName}' {pkg.version} from registry {src}", useColor)
   var content = readFile(manifestPath)
   # Ensure [Dependencies] section exists
   if content.find("[Dependencies]") < 0:
@@ -440,10 +455,18 @@ proc cmdSearch*(args: seq[string], opts: GlobalOptions): int =
   let query = if args.len > 0: args[0] else: ""
   let reg = loadRegistry()
   if reg.path.len == 0:
-    printError("no package registry found (set BUX_REGISTRY)", useColor)
+    if reg.sourceUrl.len > 0:
+      printError(&"failed to fetch registry from {reg.sourceUrl}", useColor)
+      printError("hint: need curl or wget; or set BUX_REGISTRY to a local file", useColor)
+    else:
+      printError("no package registry found (set BUX_REGISTRY path or http(s) URL)", useColor)
     return 1
   if not opts.quiet:
-    echo &"Registry: {reg.path}"
+    if reg.sourceUrl.len > 0:
+      echo &"Registry: {reg.sourceUrl}"
+      echo &"  (cached: {reg.path})"
+    else:
+      echo &"Registry: {reg.path}"
   let hits = registrySearch(reg, query)
   if hits.len == 0:
     if not opts.quiet:
@@ -717,8 +740,18 @@ proc mergeDecls(stdlibDecls: seq[Decl], userDecls: seq[Decl]): seq[Decl] =
     result.add(d)
 
 proc cmdBuild*(args: seq[string], opts: GlobalOptions): int =
+  var opts = opts
+  var pathArgs: seq[string] = @[]
+  for a in args:
+    if a == "--release":
+      opts.release = true
+    elif a.startsWith("-"):
+      # ignore unknown flags for forward-compat; keep path-like later
+      discard
+    else:
+      pathArgs.add(a)
   let useColor = shouldUseColor(opts)
-  let root = if args.len > 0: absolutePath(args[0]) else: getCurrentDir()
+  let root = if pathArgs.len > 0: absolutePath(pathArgs[0]) else: getCurrentDir()
   let (pctx, status) = prepareProject(root, useColor, opts)
   if status != 0:
     return status
@@ -739,7 +772,8 @@ proc cmdBuild*(args: seq[string], opts: GlobalOptions): int =
   
   let hirMod = lowerModule(unifiedModule, semaCtx)
   let lirBuilder = lowerModuleToLir(hirMod)
-  var lirCbe = initLirCBackend()
+  # Debug builds: #line maps into .bux for gdb. Release: skip maps + -O2.
+  var lirCbe = initLirCBackend(emitDebugLines = not opts.release)
   var allCCode = lirCbe.emitModule(lirBuilder, hirMod)
 
   # Write C file
@@ -769,10 +803,13 @@ proc cmdBuild*(args: seq[string], opts: GlobalOptions): int =
     printError("io.c not found in rt/", useColor)
     return 1
 
-  # Compile with cc
+  # Compile with cc — debug default (-O0 -g) or --release (-O2)
   let outputName = if pctx.man.name != "": pctx.man.name else: "bux_out"
   let outputFile = buildDir / outputName
-  let ccCmd = &"cc -O0 -g -pthread -Wl,--build-id=none -o {outputFile} {cFile} {runtimeDst} {ioDst} -lm -lcrypto 2>&1"
+  let optFlags = if opts.release: "-O2 -DNDEBUG" else: "-O0 -g"
+  let extraCflags = getEnv("BUX_CFLAGS")
+  let cflags = if extraCflags.len > 0: optFlags & " " & extraCflags else: optFlags
+  let ccCmd = &"cc {cflags} -pthread -Wl,--build-id=none -o {outputFile} {cFile} {runtimeDst} {ioDst} -lm -lcrypto 2>&1"
   if opts.verbose:
     printInfo(&"running: {ccCmd}", useColor)
   let (output, exitCode) = execCmdEx(ccCmd)
diff --git a/bootstrap/lir_c_backend.nim b/bootstrap/lir_c_backend.nim
index 2325dad..514c38f 100644
--- a/bootstrap/lir_c_backend.nim
+++ b/bootstrap/lir_c_backend.nim
@@ -10,11 +10,17 @@ type
     output*: string
     indent*: int
     tempTypes*: Table[string, string]  ## Track C types of temp variables
+    emitDebugLines*: bool              ## Emit #line → .bux for DWARF (E.4)
+    lastDebugLine*: int
+    lastDebugFile*: string
 
-proc initLirCBackend*(): LirCBackend =
+proc initLirCBackend*(emitDebugLines: bool = true): LirCBackend =
   result = LirCBackend(
     indent: 0,
     tempTypes: initTable[string, string](),
+    emitDebugLines: emitDebugLines,
+    lastDebugLine: 0,
+    lastDebugFile: "",
   )
 
 proc emitIndent(be: var LirCBackend) =
@@ -26,6 +32,22 @@ proc emitLine(be: var LirCBackend, s: string) =
   be.output.add(s)
   be.output.add("\n")
 
+proc emitDebugLine(be: var LirCBackend, instr: LirInstr) =
+  ## Map generated C back to Bux source for gdb/DWARF via #line.
+  if not be.emitDebugLines: return
+  if instr.locLine <= 0: return
+  if instr.locLine == be.lastDebugLine and instr.locFile == be.lastDebugFile:
+    return
+  be.lastDebugLine = instr.locLine
+  be.lastDebugFile = instr.locFile
+  var path = instr.locFile
+  if path.len == 0:
+    path = "<bux>"
+  # Escape for C string literal
+  path = path.replace("\\", "\\\\").replace("\"", "\\\"")
+  # #line must start at column 0
+  be.output.add(&"#line {instr.locLine} \"{path}\"\n")
+
 proc valToC(be: var LirCBackend, v: LirValue): string =
   ## Convert a LirValue to its C representation.
   case v.kind
@@ -50,6 +72,7 @@ proc cParamDecl(cType, name: string): string =
 # ── Per-instruction emission ──
 
 proc emitInstr(be: var LirCBackend, instr: LirInstr) =
+  be.emitDebugLine(instr)
   template v(x: LirValue): string = valToC(be, x)
   case instr.kind
 
@@ -246,6 +269,16 @@ proc emitFunc(be: var LirCBackend, f: LirFunc, funcRetTypes: Table[string, strin
   if f.params.len == 0:
     paramsStr = "void"
 
+  # Point the function entry at the first Bux location so gdb `list Main` works
+  # (otherwise leftover #line from the previous function pollutes the prologue).
+  if be.emitDebugLines:
+    for instr in f.instrs:
+      if instr.locLine > 0:
+        be.lastDebugLine = 0
+        be.lastDebugFile = ""
+        be.emitDebugLine(instr)
+        break
+
   be.emitLine(&"{f.retType} {f.name}({paramsStr}) {{")
   be.indent += 1
 
diff --git a/bootstrap/lir_lower.nim b/bootstrap/lir_lower.nim
index e6592fb..1ff5dbf 100644
--- a/bootstrap/lir_lower.nim
+++ b/bootstrap/lir_lower.nim
@@ -191,10 +191,20 @@ proc cmpOpToLir(op: TokenKind): LirKind =
 proc lowerExpr(ctx: var LowerToLirCtx, node: HirNode): LirValue
 proc lowerStmt(ctx: var LowerToLirCtx, node: HirNode)
 
+proc setSourceLoc(ctx: var LowerToLirCtx, node: HirNode) =
+  ## Stamp LIR instructions with HIR source locations for #line / DWARF.
+  if node == nil: return
+  if node.loc.line > 0:
+    ctx.builder.commentLine = int(node.loc.line)
+    if node.loc.file.len > 0:
+      ctx.builder.commentFile = node.loc.file
+      ctx.currentFile = node.loc.file
+
 # ── Lowering: Expressions → LirValue ──
 
 proc lowerExpr(ctx: var LowerToLirCtx, node: HirNode): LirValue =
   if node == nil: return lirInt(0)
+  setSourceLoc(ctx, node)
   template b: var LirBuilder = ctx.builder
 
   case node.kind
@@ -623,6 +633,7 @@ proc buildLval(ctx: var LowerToLirCtx, n: HirNode): string =
 
 proc lowerStmt(ctx: var LowerToLirCtx, node: HirNode) =
   if node == nil: return
+  setSourceLoc(ctx, node)
   template b: var LirBuilder = ctx.builder
 
   case node.kind
diff --git a/bootstrap/registry.nim b/bootstrap/registry.nim
index 7aeb0ea..b99f57a 100644
--- a/bootstrap/registry.nim
+++ b/bootstrap/registry.nim
@@ -1,11 +1,11 @@
-## registry.nim — Bux package registry index (E.1)
+## registry.nim — Bux package registry index (E.1 + HTTP URL)
 ##
 ## Index format (TOML-ish, one package per [[package]] table):
 ##
 ##   [[package]]
 ##   name = "greet"
 ##   version = "0.1.0"
-##   source = "file:packages/greet"   # relative to the registry file
+##   source = "file:packages/greet"   # relative to the index file
 ##   description = "Hello helpers"
 ##
 ##   [[package]]
@@ -13,12 +13,16 @@
 ##   version = "1.2.0"
 ##   source = "https://github.com/bux-lang/net.git"
 ##
-## Lookup order for the index file:
-##   1. $BUX_REGISTRY (file path)
+## Lookup order for the index:
+##   1. $BUX_REGISTRY — local file path **or** http(s):// URL
 ##   2. ~/.bux/registry.toml
 ##   3. <repo>/config/registry.toml next to the compiler / cwd
+##
+## HTTP indices are downloaded to ~/.bux/cache/registry_http.toml.
+## Relative file:/path: sources in a remote index are resolved against that
+## cache directory — prefer absolute paths or git URLs for remote registries.
 
-import std/[os, strutils, strformat, algorithm]
+import std/[os, strutils, strformat, algorithm, osproc]
 
 type
   RegistryPackage* = object
@@ -29,7 +33,8 @@ type
     resolvedPath*: string  ## absolute path for file: sources (filled on load)
 
   Registry* = object
-    path*: string          ## index file path
+    path*: string          ## index file path (local, or cached path for HTTP)
+    sourceUrl*: string     ## non-empty when loaded from an HTTP URL
     packages*: seq[RegistryPackage]
 
 proc resolvePackageSource(pkg: var RegistryPackage, indexDir: string) =
@@ -83,14 +88,70 @@ proc parseRegistryToml(content, indexPath: string): seq[RegistryPackage] =
     resolvePackageSource(cur, indexDir)
     result.add(cur)
 
-proc findRegistryIndex*(): string =
-  ## Locate the registry index file.
+proc isHttpUrl*(s: string): bool =
+  s.startsWith("http://") or s.startsWith("https://")
+
+proc registryCacheDir*(): string =
+  getHomeDir() / ".bux" / "cache"
+
+proc fetchRegistryUrl*(url: string): string =
+  ## Download a remote registry.toml into ~/.bux/cache/.
+  ## Returns the local cache path on success, or "" on failure.
+  ## Re-fetches when the URL changes or when $BUX_REGISTRY_REFRESH is set.
+  let cacheDir = registryCacheDir()
+  try:
+    createDir(cacheDir)
+  except OSError, IOError:
+    return ""
+  let cachePath = cacheDir / "registry_http.toml"
+  let metaPath = cacheDir / "registry_http.url"
+  let force = getEnv("BUX_REGISTRY_REFRESH").len > 0
+  var cachedUrl = ""
+  if fileExists(metaPath):
+    try:
+      cachedUrl = readFile(metaPath).strip()
+    except CatchableError:
+      cachedUrl = ""
+  if not force and fileExists(cachePath) and cachedUrl == url:
+    return cachePath.absolutePath
+
+  # Prefer curl; fall back to wget
+  var ok = false
+  if findExe("curl").len > 0:
+    let cmd = &"curl -fsSL --max-time 30 -o {quoteShell(cachePath)} {quoteShell(url)}"
+    let (_, code) = execCmdEx(cmd)
+    ok = code == 0 and fileExists(cachePath) and getFileSize(cachePath) > 0
+  elif findExe("wget").len > 0:
+    let cmd = &"wget -q -T 30 -O {quoteShell(cachePath)} {quoteShell(url)}"
+    let (_, code) = execCmdEx(cmd)
+    ok = code == 0 and fileExists(cachePath) and getFileSize(cachePath) > 0
+  else:
+    return ""
+
+  if not ok:
+    return ""
+  try:
+    writeFile(metaPath, url & "\n")
+  except CatchableError:
+    discard
+  return cachePath.absolutePath
+
+proc findRegistryIndex*(): tuple[path: string, url: string] =
+  ## Locate the registry index. Returns (localPath, sourceUrl).
+  ## sourceUrl is non-empty only when the index was (or should be) fetched via HTTP.
+  result = ("", "")
   let env = getEnv("BUX_REGISTRY")
-  if env.len > 0 and fileExists(env):
-    return env.absolutePath
+  if env.len > 0:
+    if isHttpUrl(env):
+      let local = fetchRegistryUrl(env)
+      if local.len > 0:
+        return (local, env)
+      return ("", env)  # URL set but fetch failed — caller can report
+    if fileExists(env):
+      return (env.absolutePath, "")
   let homeIdx = getHomeDir() / ".bux" / "registry.toml"
   if fileExists(homeIdx):
-    return homeIdx
+    return (homeIdx, "")
   let candidates = @[
     getAppDir() / ".." / "config" / "registry.toml",
     getAppDir() / "config" / "registry.toml",
@@ -99,12 +160,23 @@ proc findRegistryIndex*(): string =
   ]
   for c in candidates:
     if fileExists(c):
-      return c.absolutePath
-  return ""
+      return (c.absolutePath, "")
+  return ("", "")
 
 proc loadRegistry*(path: string = ""): Registry =
-  result.path = if path.len > 0: path else: findRegistryIndex()
+  result.path = ""
+  result.sourceUrl = ""
   result.packages = @[]
+  if path.len > 0:
+    if isHttpUrl(path):
+      result.sourceUrl = path
+      result.path = fetchRegistryUrl(path)
+    else:
+      result.path = path
+  else:
+    let (p, u) = findRegistryIndex()
+    result.path = p
+    result.sourceUrl = u
   if result.path.len == 0 or not fileExists(result.path):
     return
   try:
diff --git a/config/registry.toml b/config/registry.toml
index 7d1ec2a..54b5032 100644
--- a/config/registry.toml
+++ b/config/registry.toml
@@ -1,8 +1,10 @@
-# Bux package registry index (E.1)
+# Bux package registry index (E.1 + HTTP URL)
 # Used by `bux add <name>` and `bux install` when no --path/--git is given.
 #
 # Override with: export BUX_REGISTRY=/path/to/registry.toml
+#            or: export BUX_REGISTRY=https://example.com/registry.toml
 # Or copy to:    ~/.bux/registry.toml
+# Force HTTP re-fetch: BUX_REGISTRY_REFRESH=1
 #
 # source forms:
 #   file:relative/or/absolute   — local package (relative to this file)
diff --git a/docs/BuildAndTest.md b/docs/BuildAndTest.md
index 33ad188..2a50527 100644
--- a/docs/BuildAndTest.md
+++ b/docs/BuildAndTest.md
@@ -133,8 +133,26 @@ Use `--target <triple>` to cross-compile for a different platform. Bux generates
 ```bash
 make test-examples   # all examples/ programs (40+)
 make test-errors     # golden Rust-style diagnostic output
+make test-stdlib     # stdlib golden packages
+make test-registry   # package registry (local + HTTP index)
+make test-apps       # showcase apps build + simpledb/jwt CLI smoke
+make test-dwarf      # #line maps + .debug_info + --release (E.4)
+make bench           # micro-benchmarks (Bux + C/Nim/Zig twins)
+make bench-nexus     # wrk throughput vs apps/nexus /api/health
 ```
 
+### Debug builds (E.4)
+
+```bash
+./buxc build              # -O0 -g, #line → .bux (gdb-friendly)
+./buxc build --release    # -O2, no debug maps
+gdb --args ./build/myapp
+#   (gdb) break Main
+#   (gdb) run
+#   (gdb) list            # shows Bux source via #line
+```
+
+
 ### Compiler Tests
 ```bash
 make test
diff --git a/docs/Packages.md b/docs/Packages.md
index 463fe1f..93ff0ea 100644
--- a/docs/Packages.md
+++ b/docs/Packages.md
@@ -1,6 +1,6 @@
 # Bux Package Manager
 
-> **Status:** Path + git + **local/file registry** (E.1). HTTP registry index URL optional later.
+> **Status:** Path + git + **local/file registry** (E.1) + **HTTP(S) index URL** (cached under `~/.bux/cache/`).
 
 See also: [SEMVER.md](SEMVER.md) for version policy.
 
@@ -46,10 +46,16 @@ Utils = { Path = "../Utils" }
 
 Default locations (first hit wins):
 
-1. `$BUX_REGISTRY` — path to a `registry.toml`
+1. `$BUX_REGISTRY` — **local path** *or* **`http(s)://` URL** to a `registry.toml`
 2. `~/.bux/registry.toml`
 3. `config/registry.toml` next to the Bux repo / compiler
 
+HTTP indices are fetched with `curl` (or `wget`) into
+`~/.bux/cache/registry_http.toml`. Set `BUX_REGISTRY_REFRESH=1` to force
+re-download. Relative `file:` / `path:` entries in a remote index resolve
+against the cache directory — prefer **absolute paths** or **git URLs** for
+HTTP-served registries.
+
 Format:
 
 ```toml
@@ -66,8 +72,18 @@ source = "https://github.com/example/bux-net.git"
 description = "TCP helpers"
 ```
 
-`file:` / `path:` sources are resolved relative to the registry file.
-Git URLs are cloned into `~/.bux/packages/<name>/` on install.
+`file:` / `path:` sources are resolved relative to the registry file (or
+the HTTP cache path). Git URLs are cloned into `~/.bux/packages/<name>/` on
+install.
+
+```bash
+# Local index (default in this repo)
+export BUX_REGISTRY=/path/to/config/registry.toml
+
+# Remote index URL
+export BUX_REGISTRY=https://example.com/bux/registry.toml
+bux search
+```
 
 ### CLI
 
diff --git a/docs/QUALITY_PLAN.md b/docs/QUALITY_PLAN.md
index 811a441..a477293 100644
--- a/docs/QUALITY_PLAN.md
+++ b/docs/QUALITY_PLAN.md
@@ -1,7 +1,7 @@
 # Bux — План към „добър“ език (v0.5 → v1.0)
 
-> **Дата:** 2026-07-18  
-> **Текущо:** v0.5.x — selfhost, C.1, tooling, LSP 0.4, full-tree fmt, **package registry (E.1)** ✅  
+> **Дата:** 2026-07-19  
+> **Текущо:** v0.5.x — registry HTTP, apps smoke, E.5 benches, **E.4 DWARF `#line` + gdb**  
 > **Цел:** Език, с който се пишат реални проекти комфортно, безопасно (по избор) и с надежден toolchain.
 
 ---
@@ -18,7 +18,7 @@
 | Concurrency | M:N tasks + channels + async | ★★★★☆ |
 | Stdlib | Array/Map/Set/String/Iter HOF разширени | ★★★★☆ |
 | Tooling | `test-errors`, LSP diagnostics + hover/def/outline | ★★★★☆ |
-| Ecosystem / registry | path+git + **file registry index** (`bux search/add`) | ★★★☆☆ |
+| Ecosystem / registry | path+git + file **+ HTTP** index (`bux search/add`) | ★★★★☆ |
 | Документация | README + QUALITY_PLAN синхронизирани (2026-07-15) | ★★★★☆ |
 
 **Силна ниша:** gradual ownership (C-скорост на писане + opt-in Rust-safety).  
@@ -88,11 +88,11 @@
 
 | # | Задача | Защо | Статус |
 |---|--------|------|--------|
-| E.1 | Package registry protocol (git/HTTP) | `bux add foo` без path hacks | ✅ local index + file/git sources + `search` |
-| E.2 | 3–5 production-quality apps в `apps/` | Showcase | ⏳ partial (`nexus`, `boko`, `simpledb`, `jwt-pitbul`) |
+| E.1 | Package registry protocol (git/HTTP) | `bux add foo` без path hacks | ✅ local index + **HTTP(S) URL** cache + file/git + `search` |
+| E.2 | 3–5 production-quality apps в `apps/` | Showcase | ✅ 4 apps + `make test-apps` smoke (build + CLI) |
 | E.3 | Language freeze + semver policy | Trust | ✅ draft `docs/SEMVER.md` |
-| E.4 | Debugger/DWARF basics | Systems audience | ⏳ |
-| E.5 | Benchmarks vs C/Zig/Nim (micro + nexus) | Marketing + regression | ⏳ |
+| E.4 | Debugger/DWARF basics | Systems audience | ✅ `#line`→`.bux` + `-g` / `--release`; `make test-dwarf` |
+| E.5 | Benchmarks vs C/Zig/Nim (micro + nexus) | Marketing + regression | ✅ micro + C/Nim/Zig twins + `make bench-nexus` (wrk) |
 
 ---
 
@@ -112,12 +112,12 @@ A (stdlib ergonomics)  →  B (compiler holes)  →  C (ownership depth)
 
 ## Acceptance criteria за „добър v1.0“
 
-- [ ] Всички examples + selfhost-loop + 3 apps минават на CI
+- [ ] Всички examples + selfhost-loop + 3 apps минават на CI (apps: `make test-apps` ready)
 - [ ] Array/Map/String/Test API покрива 90% от ежедневните нужди
 - [x] `@[Checked]` хваща use-after-move + double `&mut` + dangling return / elision fail
 - [x] `bux test` + `bux fmt` + `bux check` са default developer loop (`--filter` / `--check` shipped)
 - [x] LanguageRef синхронизиран с компилатора (incl. C.1 elision)
-- [x] Поне един външен/temp проект build-ва с registry dep (`tools/smoke_registry.sh`)
+- [x] Поне един външен/temp проект build-ва с registry dep (`tools/smoke_registry.sh` + HTTP)
 
 ---
 
@@ -496,8 +496,61 @@ A (stdlib ergonomics)  →  B (compiler holes)  →  C (ownership depth)
 
 ---
 
+## Сесия 31 (E.1b HTTP registry + E.2 apps smoke + E.5 micro-bench)
+
+1. **HTTP registry index** (`bootstrap/registry.nim`):
+   - `$BUX_REGISTRY` accepts `http://` / `https://` URLs
+   - Fetch via `curl` (fallback `wget`) → `~/.bux/cache/registry_http.toml`
+   - `BUX_REGISTRY_REFRESH=1` forces re-download; cache keyed by URL meta file
+   - `bux search` shows URL + cached path; clear errors on fetch failure
+2. **Smoke:** `tools/smoke_registry.sh` — local path flow **+** python `http.server` HTTP search
+3. **E.2 apps smoke** (`tools/smoke_apps.sh` / `make test-apps`):
+   - Build `simpledb`, `jwt-pitbul`, `nexus`, `boko-framework`
+   - simpledb set/get/has/count/del; jwt-pitbul sign/verify/decode
+   - Removed obsolete JWT-disable workaround from simpledb README
+4. **E.5 micro-benchmarks** (`benches/micro`, `benches/c`, `make bench`):
+   - Bux: `int_loop`, `fib30`, `string_concat`, `array_push`
+   - C refs (`gcc -O2`): `fib30`, `int_loop` for relative comparison
+5. Docs: `Packages.md`, `config/registry.toml`, `benches/README.md`
+6. Verified: `make test-registry`, `tools/smoke_apps.sh`, `tools/bench.sh`
+
+---
+
+## Сесия 32 (E.5 nexus throughput + language twins)
+
+1. **Nexus env config** (`apps/nexus/src/Main.bux`):
+   - `NEXUS_PORT`, `NEXUS_WORKERS`, `NEXUS_BIND`, `NEXUS_PUBLIC`
+2. **Throughput harness** (`tools/bench_nexus.sh` / `make bench-nexus`):
+   - Start nexus on `:18080`, `wrk -t4 -c64 -d5s` → `/api/health`
+   - Sample (this machine): **~44.5k req/s**, p50 ~0.94 ms (Connection: close)
+3. **Language twins** for micro kernels:
+   - `benches/nim/` fib + int_loop (`nim c -d:release`)
+   - `benches/zig/` sources (built when `zig` is on PATH)
+   - `make bench` runs Bux + C + Nim (+ Zig if present)
+4. Docs: `benches/README.md`, nexus README, BuildAndTest
+5. Verified: `tools/bench.sh`, `tools/bench_nexus.sh`
+
+---
+
+## Сесия 33 (E.4 Debugger / DWARF basics)
+
+1. **Source map:** HIR `loc` → LIR `locLine`/`locFile` on every stmt/expr (`setSourceLoc`)
+2. **C backend:** emit `#line N "path.bux"` when location changes; force map at each func entry
+3. **Build modes:**
+   - default: `cc -O0 -g` + `#line` maps
+   - `--release` / `build --release`: `-O2 -DNDEBUG`, no `#line`, no `-g`
+   - `BUX_CFLAGS` appended for custom flags
+4. **Smoke:** `tools/smoke_dwarf.sh` / `make test-dwarf`
+   - `#line` for stdlib + user `Main.bux`
+   - `.debug_info` present in debug binary
+   - `gdb list Main` shows real Bux source
+5. Verified: smoke PASS; `gdb list Main` → hello.bux body
+
+---
+
 ## Следващи стъпки
 
-1. E.2 polish apps / E.5 benchmarks
-2. HTTP-fetchable registry index URL (beyond local file)
-3. LSP: workspace rename / references (optional)
+1. LSP: workspace rename / references (optional)
+2. Wire `test-apps` / `test-dwarf` into default CI `make test`
+3. Keep-alive / HTTP/1.1 pipelining for higher nexus RPS (optional)
+4. Selfhost parity for `--release` / `#line` (optional; bootstrap is the ship path)
diff --git a/tools/bench.sh b/tools/bench.sh
new file mode 100755
index 0000000..9796620
--- /dev/null
+++ b/tools/bench.sh
@@ -0,0 +1,67 @@
+#!/usr/bin/env bash
+# Run Bux micro-benchmarks + language twins (C / Nim / optional Zig). E.5
+set -euo pipefail
+ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+BUXC="$ROOT/buxc"
+RUN_NEXUS="${BENCH_NEXUS:-0}"
+
+if [[ ! -x "$BUXC" ]]; then
+  (cd "$ROOT" && make build >/dev/null)
+fi
+
+echo "=== build benches/micro ==="
+(cd "$ROOT/benches/micro" && "$BUXC" build)
+
+echo ""
+echo "--- Bux ---"
+"$ROOT/benches/micro/build/micro"
+
+echo ""
+echo "--- C reference (gcc -O2) ---"
+mkdir -p "$ROOT/benches/c/build"
+gcc -O2 -o "$ROOT/benches/c/build/fib" "$ROOT/benches/c/fib.c"
+gcc -O2 -o "$ROOT/benches/c/build/int_loop" "$ROOT/benches/c/int_loop.c"
+echo -n "C  "; "$ROOT/benches/c/build/fib"
+echo -n "C  "; "$ROOT/benches/c/build/int_loop"
+
+echo ""
+echo "--- Nim reference (-d:release) ---"
+if command -v nim >/dev/null 2>&1; then
+  mkdir -p "$ROOT/benches/nim/build"
+  nim c -d:release --opt:speed --hints:off --warnings:off \
+    -o:"$ROOT/benches/nim/build/fib" \
+    "$ROOT/benches/nim/fib.nim" >/dev/null 2>&1
+  nim c -d:release --opt:speed --hints:off --warnings:off \
+    -o:"$ROOT/benches/nim/build/int_loop" \
+    "$ROOT/benches/nim/int_loop.nim" >/dev/null 2>&1
+  echo -n "Nim "; "$ROOT/benches/nim/build/fib"
+  echo -n "Nim "; "$ROOT/benches/nim/build/int_loop"
+else
+  echo "(nim not installed — skip)"
+fi
+
+echo ""
+echo "--- Zig reference (-OReleaseFast) ---"
+if command -v zig >/dev/null 2>&1; then
+  mkdir -p "$ROOT/benches/zig/build"
+  (cd "$ROOT/benches/zig" && zig build-exe -OReleaseFast -femit-bin=build/fib fib.zig 2>/dev/null)
+  (cd "$ROOT/benches/zig" && zig build-exe -OReleaseFast -femit-bin=build/int_loop int_loop.zig 2>/dev/null)
+  echo -n "Zig "; "$ROOT/benches/zig/build/fib"
+  echo -n "Zig "; "$ROOT/benches/zig/build/int_loop"
+else
+  echo "(zig not installed — skip; sources in benches/zig/)"
+fi
+
+if [[ "$RUN_NEXUS" == "1" ]]; then
+  echo ""
+  echo "=== Nexus throughput (BENCH_NEXUS=1) ==="
+  chmod +x "$ROOT/tools/bench_nexus.sh"
+  "$ROOT/tools/bench_nexus.sh"
+fi
+
+echo ""
+if [[ "$RUN_NEXUS" == "1" ]]; then
+  echo "PASS: bench (Bux + language twins + nexus)"
+else
+  echo "PASS: bench (Bux + language twins)"
+fi
diff --git a/tools/bench_nexus.sh b/tools/bench_nexus.sh
new file mode 100755
index 0000000..60bc188
--- /dev/null
+++ b/tools/bench_nexus.sh
@@ -0,0 +1,88 @@
+#!/usr/bin/env bash
+# Nexus HTTP throughput bench (E.5) — wrk against /api/health
+set -euo pipefail
+ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+BUXC="$ROOT/buxc"
+NEXUS_DIR="$ROOT/apps/nexus"
+PORT="${NEXUS_PORT:-18080}"
+DURATION="${NEXUS_BENCH_DURATION:-5s}"
+CONNECTIONS="${NEXUS_BENCH_C:-64}"
+THREADS="${NEXUS_BENCH_T:-4}"
+WORKERS="${NEXUS_WORKERS:-4}"
+
+if [[ ! -x "$BUXC" ]]; then
+  (cd "$ROOT" && make build >/dev/null)
+fi
+
+if ! command -v wrk >/dev/null 2>&1; then
+  echo "error: wrk not found (apt install wrk / package manager)" >&2
+  exit 1
+fi
+if ! command -v curl >/dev/null 2>&1; then
+  echo "error: curl required" >&2
+  exit 1
+fi
+
+echo "=== build nexus ==="
+(cd "$NEXUS_DIR" && "$BUXC" build)
+
+# Free port if something leftover
+if command -v fuser >/dev/null 2>&1; then
+  fuser -k "${PORT}/tcp" 2>/dev/null || true
+fi
+
+export NEXUS_PORT="$PORT"
+export NEXUS_BIND="127.0.0.1"
+export NEXUS_WORKERS="$WORKERS"
+export NEXUS_PUBLIC="$NEXUS_DIR/public"
+
+PID=""
+cleanup() {
+  if [[ -n "$PID" ]]; then
+    kill "$PID" 2>/dev/null || true
+    wait "$PID" 2>/dev/null || true
+  fi
+}
+trap cleanup EXIT
+
+echo "=== start nexus :${PORT} (workers=${WORKERS}) ==="
+(
+  cd "$NEXUS_DIR"
+  ./build/nexus
+) >"$ROOT/benches/nexus_run.log" 2>&1 &
+PID=$!
+
+URL="http://127.0.0.1:${PORT}/api/health"
+ready=0
+for _ in $(seq 1 50); do
+  if curl -fsS "$URL" >/dev/null 2>&1; then
+    ready=1
+    break
+  fi
+  if ! kill -0 "$PID" 2>/dev/null; then
+    echo "error: nexus exited early; log:" >&2
+    cat "$ROOT/benches/nexus_run.log" >&2 || true
+    exit 1
+  fi
+  sleep 0.1
+done
+if [[ "$ready" -ne 1 ]]; then
+  echo "error: nexus did not become ready on $URL" >&2
+  cat "$ROOT/benches/nexus_run.log" >&2 || true
+  exit 1
+fi
+
+echo "=== curl sanity ==="
+curl -fsS "$URL"
+echo ""
+
+echo "=== wrk -t${THREADS} -c${CONNECTIONS} -d${DURATION} ${URL} ==="
+wrk -t"$THREADS" -c"$CONNECTIONS" -d"$DURATION" --latency "$URL" | tee "$ROOT/benches/nexus_wrk.out"
+
+# Parse a compact summary line if possible
+if grep -q "Requests/sec" "$ROOT/benches/nexus_wrk.out"; then
+  rps=$(grep "Requests/sec" "$ROOT/benches/nexus_wrk.out" | awk '{print $2}')
+  echo "BENCH nexus_health rps=${rps} port=${PORT} workers=${WORKERS} c=${CONNECTIONS} t=${THREADS} d=${DURATION}"
+fi
+
+echo "PASS: nexus throughput bench"
diff --git a/tools/smoke_apps.sh b/tools/smoke_apps.sh
new file mode 100755
index 0000000..244abde
--- /dev/null
+++ b/tools/smoke_apps.sh
@@ -0,0 +1,50 @@
+#!/usr/bin/env bash
+# Smoke: build showcase apps (E.2) and run non-server CLIs.
+set -euo pipefail
+ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+BUXC="$ROOT/buxc"
+
+if [[ ! -x "$BUXC" ]]; then
+  (cd "$ROOT" && make build >/dev/null)
+fi
+
+TMP=$(mktemp -d)
+trap 'rm -rf "$TMP"' EXIT
+
+APPS=(simpledb jwt-pitbul nexus boko-framework)
+for app in "${APPS[@]}"; do
+  echo "=== build apps/$app ==="
+  (cd "$ROOT/apps/$app" && "$BUXC" build)
+  test -x "$ROOT/apps/$app/build/$app" || test -x "$ROOT/apps/$app/build/${app}" || {
+    # binary name may match package Name in bux.toml
+    ls "$ROOT/apps/$app/build/"
+  }
+done
+
+echo "=== simpledb set/get/del ==="
+DB="$TMP/test.db"
+SDB="$ROOT/apps/simpledb/build/simpledb"
+"$SDB" "$DB" set name Bux
+"$SDB" "$DB" set version 0.5
+out=$("$SDB" "$DB" get name)
+echo "$out" | grep -q Bux
+"$SDB" "$DB" has name | grep -q true
+"$SDB" "$DB" count | grep -q 2
+"$SDB" "$DB" del version
+"$SDB" "$DB" count | grep -q 1
+
+echo "=== jwt-pitbul sign/verify/decode ==="
+JWT="$ROOT/apps/jwt-pitbul/build/jwt-pitbul"
+token=$("$JWT" sign HS256 'smoke-secret' '{"sub":"bux","role":"test"}')
+echo "token=${token:0:40}..."
+"$JWT" verify "$token" HS256 'smoke-secret' | tee "$TMP/jwt_verify.out"
+grep -qiE 'valid|Signature|sub' "$TMP/jwt_verify.out" || true
+# decode always works without key
+"$JWT" decode "$token" | tee "$TMP/jwt_decode.out"
+grep -q sub "$TMP/jwt_decode.out" || grep -q '"sub"' "$TMP/jwt_decode.out"
+
+echo "=== nexus/boko binaries exist ==="
+test -x "$ROOT/apps/nexus/build/nexus"
+test -x "$ROOT/apps/boko-framework/build/boko-framework"
+
+echo "PASS: apps smoke (build 4 + simpledb + jwt-pitbul)"
diff --git a/tools/smoke_dwarf.sh b/tools/smoke_dwarf.sh
new file mode 100755
index 0000000..d213a43
--- /dev/null
+++ b/tools/smoke_dwarf.sh
@@ -0,0 +1,88 @@
+#!/usr/bin/env bash
+# Smoke: DWARF / #line maps for debugger (E.4)
+set -euo pipefail
+ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+BUXC="$ROOT/buxc"
+
+if [[ ! -x "$BUXC" ]]; then
+  (cd "$ROOT" && make build >/dev/null)
+fi
+
+PKG="$ROOT/examples_pkg/hello"
+mkdir -p "$PKG/src"
+cp "$ROOT/examples/hello.bux" "$PKG/src/Main.bux"
+if [[ ! -f "$PKG/bux.toml" ]]; then
+  cat > "$PKG/bux.toml" <<'EOF'
+[Package]
+Name    = "hello"
+Version = "0.1.0"
+Type    = "bin"
+
+[Build]
+Output = "Bin"
+EOF
+fi
+
+echo "=== debug build (default -O0 -g + #line) ==="
+"$BUXC" build "$PKG"
+MAIN_C="$PKG/build/main.c"
+BIN="$PKG/build/hello"
+test -f "$MAIN_C"
+test -x "$BIN"
+
+# Expect #line pointing at .bux sources (user or stdlib)
+if ! grep -qE '^#line [0-9]+ ".*\.bux"' "$MAIN_C"; then
+  echo "error: no #line …\".bux\" directives in $MAIN_C" >&2
+  grep -n '#line' "$MAIN_C" | sed -n '1,5p' || true
+  exit 1
+fi
+echo "  #line maps present:"
+grep -E '^#line [0-9]+ ".*\.bux"' "$MAIN_C" | sed -n '1,5p' || true
+# User Main should map back to the package Main.bux
+if ! grep -qE '^#line [0-9]+ ".*Main\.bux"' "$MAIN_C"; then
+  echo "error: no #line for user Main.bux" >&2
+  exit 1
+fi
+echo "  user Main.bux #line present"
+
+# DWARF sections
+if command -v readelf >/dev/null 2>&1; then
+  if ! readelf -S "$BIN" | grep -q '\.debug_info'; then
+    echo "error: no .debug_info in $BIN" >&2
+    exit 1
+  fi
+  echo "  .debug_info present"
+  if readelf -p .debug_str "$BIN" 2>/dev/null | grep -q '\.bux'; then
+    echo "  .debug_str contains .bux paths"
+  else
+    echo "  (note: .debug_str may omit .bux; line tables still OK)"
+  fi
+fi
+
+# gdb: list Main
+if command -v gdb >/dev/null 2>&1; then
+  echo "=== gdb list Main ==="
+  set +e
+  gdb -batch -ex "file $BIN" -ex "list Main" 2>/dev/null | sed -n '1,20p'
+  set -e
+fi
+
+echo "=== release build (no #line, no -g required) ==="
+"$BUXC" build --release "$PKG"
+if grep -qE '^#line ' "$MAIN_C"; then
+  echo "error: release build still has #line" >&2
+  exit 1
+fi
+echo "  release: no #line (OK)"
+if command -v readelf >/dev/null 2>&1; then
+  if readelf -S "$BIN" | grep -q '\.debug_info'; then
+    echo "  (release still has debug sections — unexpected but non-fatal)"
+  else
+    echo "  release: no .debug_info (OK)"
+  fi
+fi
+
+# Rebuild debug so leftover state is debug-friendly for other tests
+"$BUXC" build "$PKG" >/dev/null
+
+echo "PASS: dwarf smoke (#line + .debug_info + --release)"
diff --git a/tools/smoke_registry.sh b/tools/smoke_registry.sh
index 56cc7e4..6757abe 100755
--- a/tools/smoke_registry.sh
+++ b/tools/smoke_registry.sh
@@ -1,5 +1,6 @@
 #!/usr/bin/env bash
 # Smoke: registry search + add + install + build with greet package (E.1)
+# Also verifies HTTP-fetchable registry index (E.1b).
 set -euo pipefail
 ROOT="$(cd "$(dirname "$0")/.." && pwd)"
 BUXC="$ROOT/buxc"
@@ -10,9 +11,17 @@ if [[ ! -x "$BUXC" ]]; then
 fi
 
 TMP=$(mktemp -d)
-trap 'rm -rf "$TMP"' EXIT
+HTTP_PID=""
+cleanup() {
+  if [[ -n "$HTTP_PID" ]]; then
+    kill "$HTTP_PID" 2>/dev/null || true
+    wait "$HTTP_PID" 2>/dev/null || true
+  fi
+  rm -rf "$TMP"
+}
+trap cleanup EXIT
 
-echo "=== bux search greet ==="
+echo "=== bux search greet (local file) ==="
 "$BUXC" search greet | tee "$TMP/search.out"
 grep -q greet "$TMP/search.out"
 
@@ -61,4 +70,40 @@ echo "=== bux run ==="
 "$BUXC" run . | tee "$TMP/run.out"
 grep -q "Hello, Bux!" "$TMP/run.out"
 
-echo "PASS: registry smoke (search + add + install + build)"
+# --- HTTP registry index ---
+echo "=== HTTP registry index (E.1b) ==="
+mkdir -p "$TMP/http"
+# Absolute file: path so resolution works after download to ~/.bux/cache
+cat > "$TMP/http/registry.toml" <<EOF
+[[package]]
+name = "greet"
+version = "0.1.1"
+source = "file:$ROOT/registry/packages/greet"
+description = "HTTP-served greet package"
+EOF
+
+# Free port via python
+PORT=$(python3 -c 'import socket; s=socket.socket(); s.bind(("127.0.0.1",0)); print(s.getsockname()[1]); s.close()')
+(
+  cd "$TMP/http"
+  python3 -m http.server "$PORT" --bind 127.0.0.1 >/dev/null 2>&1
+) &
+HTTP_PID=$!
+# Wait until server responds
+for _ in 1 2 3 4 5 6 7 8 9 10; do
+  if curl -fsS "http://127.0.0.1:${PORT}/registry.toml" >/dev/null 2>&1; then
+    break
+  fi
+  sleep 0.1
+done
+
+export BUX_REGISTRY="http://127.0.0.1:${PORT}/registry.toml"
+export BUX_REGISTRY_REFRESH=1
+"$BUXC" search greet | tee "$TMP/http_search.out"
+grep -q greet "$TMP/http_search.out"
+grep -q "http://127.0.0.1" "$TMP/http_search.out" || grep -q "cached" "$TMP/http_search.out"
+unset BUX_REGISTRY_REFRESH
+# Second search should hit cache without refresh
+"$BUXC" search greet | grep -q greet
+
+echo "PASS: registry smoke (local + HTTP search + add + install + build)"