fix(benchmark): use real FastSync flags and Release builds

The benchmark tool used stale rsync-style spellings that map to

different FastSync options, so it never enabled the features it

claimed to measure:

  -c -> --checksum (not compression)

  -m -> --prune-empty-dirs (not multithreading)

  -s -> --secluded-args, a no-op (not chunk serialization)

  -f -> --filter, needs an argument (not sendfile)

Replace them with the real flags (-z, -j, --chunk-serialization,

--sendfile), force CMAKE_BUILD_TYPE=Release, route informational

output to stderr so --output json emits valid JSON, surface

client/rsync failures instead of silently dropping them, and widen

the results table for the longer config names. Update the benchmark

skill to match (correct flags, server invocation, and replace the

nonexistent test.py --full with benchmark/bench.py).

.opencode/skills/benchmark/SKILL.md

@@ -38,50 +38,62 @@ dd if=/dev/urandom of=/tmp/fastsync_bench/src/large.bin bs=1M count=10 2>/dev/nu
 Test each configuration 3 times, record median:
 
 ```bash
+# Real FastSync flags: -z=compression, -j=multithreading,
+# --chunk-serialization, --sendfile (long form only).  The old rsync-style
+# spellings -c/-m/-s/-f are NOT the same options (-c=--checksum,
+# -m=--prune-empty-dirs, -s=--secluded-args, -f=--filter) and must not be used.
 CONFIGS=(
   "Standard|"
-  "Compression|-c"
-  "Multithreading|-m"
-  "MT+Compression|-m -c"
-  "Chunk Serialization|-s"
-  "MT+Compression+Chunk|-m -c -s"
-  "Sendfile|-f"
+  "Compression|-z"
+  "Multithreading|-j"
+  "MT+Compression|-j -z"
+  "Chunk Serialization|-j -z --chunk-serialization"
+  "Sendfile|--sendfile"
 )
 
+PORT=18080
 for config in "${CONFIGS[@]}"; do
   IFS='|' read -r name flags <<< "$config"
   echo "=== $name ==="
   for run in 1 2 3; do
     rm -rf /tmp/fastsync_bench/dst
     mkdir -p /tmp/fastsync_bench/dst
-    
-    ./build/server &
+
+    ./build/server -p "$PORT" --allow-unauthenticated &
     SERVER_PID=$!
     sleep 0.5
-    
+
     START=$(date +%s%N)
     ./build/client --source-dir /tmp/fastsync_bench/src \
       --dest-dir /tmp/fastsync_bench/dst \
+      --server-port "$PORT" \
       --save-to-disk $flags
     END=$(date +%s%N)
-    
+
     ELAPSED=$(( (END - START) / 1000000 ))
     echo "  Run $run: ${ELAPSED}ms"
-    
+
     kill $SERVER_PID 2>/dev/null
     wait $SERVER_PID 2>/dev/null
   done
 done
 ```
 
-### Step 4: Full Integration Benchmark (Optional)
+### Step 4: Full Benchmark Tool (Preferred)
+
+The maintained benchmark tool is `benchmark/bench.py`. It handles building,
+data generation, network shaping (LAN/WAN profiles or custom `--delay`/`--jitter`/
+`--throughput`/`--loss`), rsync comparison, and JSON/table reporting:
 
-For comprehensive benchmarking with network shaping:
 ```bash
-python3 test.py --full
+python3 benchmark/bench.py --help
+python3 benchmark/bench.py --runs 5 --profiles unlimited
+python3 benchmark/bench.py --size-mb 100 --random-ratio 0.5 --output json
+python3 benchmark/bench.py --delay 50ms --jitter 10ms --throughput 100mbit
 ```
 
-This tests LAN/WAN profiles, SSH, TLS, and compares against rsync.
+Network shaping needs root (`tc`/`netem` on `lo`). SSH and TLS coverage lives in
+the pytest integration suite, not the benchmark tool.
 
 ### Step 5: Report Results
 
@@ -92,13 +104,14 @@ Platform: <OS, CPU, network>
 
 Configuration          | Run 1   | Run 2   | Run 3   | Median
 -----------------------|---------|---------|---------|--------
-Standard               | 0.12s   | 0.11s   | 0.12s   | 0.12s
-Compression (-c)       | 0.09s   | 0.08s   | 0.09s   | 0.09s
-Multithreading (-m)    | 0.07s   | 0.07s   | 0.08s   | 0.07s
-MT+Compression (-m -c) | 0.05s   | 0.05s   | 0.06s   | 0.05s
-Sendfile (-f)          | 0.04s   | 0.04s   | 0.04s   | 0.04s
+Standard                            | 0.12s   | 0.11s   | 0.12s   | 0.12s
+Compression (-z)                    | 0.09s   | 0.08s   | 0.09s   | 0.09s
+Multithreading (-j)                 | 0.07s   | 0.07s   | 0.08s   | 0.07s
+MT+Compression (-j -z)              | 0.05s   | 0.05s   | 0.06s   | 0.05s
+Chunk Serialization (--chunk-serialization) | 0.05s | 0.04s | 0.05s | 0.05s
+Sendfile (--sendfile)               | 0.04s   | 0.04s   | 0.04s   | 0.04s
 
-Best configuration: MT+Compression (-m -c)
+Best configuration: Sendfile (--sendfile)
 Throughput: <X> MB/s
 ```