single query benchmark for Claude Code - don't pin model by default

Author: guredd

benchmark/README.md

@@ -67,7 +67,9 @@ retrieval measurably changes the answer's cost and quality.
 ./single-query-bench-claude.ps1 [-Model <id>] [-Prompt "your query"]
 ```
 
-- Default model is `claude-opus-4-8`. If the query is omitted, you're prompted for it.
+- By default no `--model` is passed, so Claude Code uses its own default model (your `/model`
+  setting). Pass `--model` / `-Model` to benchmark a specific one. If the query is omitted,
+  you're prompted for it.
 - Follow the on-screen steps. Before each Claude launch the script pauses for a keypress so
   you can read the instructions; the TUI then takes over the terminal.
 - **In the measured session, do exactly ONE turn** (paste query → wait → `/exit`), or the

benchmark/single-query-bench-claude.ps1

@@ -23,11 +23,14 @@
 [CmdletBinding()]
 param(
     [string]$Prompt,
-    [string]$Model = "claude-opus-4-8"
+    [string]$Model   # empty => Claude Code's default model
 )
 
 $ErrorActionPreference = "Stop"
 
+# Only pass --model when one was given, so the default follows the user's Claude Code config.
+$modelArgs = @(if ($Model) { '--model', $Model })
+
 # --- Environment we will toggle. Capture originals so we can restore them. -----------------
 $cacheVars = @{
     "DISABLE_PROMPT_CACHING"   = $null   # keep caching ON ($null => remove if set in env)
@@ -183,14 +186,14 @@ function Invoke-ClaudeRun([string]$label, [string]$query) {
     # --- Turn 1: warm-up (writes the TUI prefix into cache) --------------------------------
     Write-Host "WARM-UP: in Claude, type  hi  and press Enter; wait for the reply, then /exit." -ForegroundColor Yellow
     Wait-Key "  Press any key to start the WARM-UP session..."
-    Start-Process -FilePath $ClaudeExe -ArgumentList '--model', $Model, '--append-system-prompt', $nonce -WorkingDirectory $WorkingDir -NoNewWindow -Wait
+    Start-Process -FilePath $ClaudeExe -ArgumentList ($modelArgs + '--append-system-prompt', $nonce) -WorkingDirectory $WorkingDir -NoNewWindow -Wait
 
     # --- Turn 2: measured (reads the prefix warm; keep it to ONE turn) ---------------------
     Set-Clipboard -Value $query
     Write-Host "MEASURED: the query is on your clipboard. Paste it (Ctrl+V), press Enter, wait, then /exit." -ForegroundColor Yellow
     Write-Host "          Do exactly ONE turn so the cost is just the query." -ForegroundColor DarkGray
     Wait-Key "  Press any key to start the MEASURED session..."
-    Start-Process -FilePath $ClaudeExe -ArgumentList '--model', $Model, '--append-system-prompt', $nonce -WorkingDirectory $WorkingDir -NoNewWindow -Wait
+    Start-Process -FilePath $ClaudeExe -ArgumentList ($modelArgs + '--append-system-prompt', $nonce) -WorkingDirectory $WorkingDir -NoNewWindow -Wait
 
     # Read official metrics; retry in case the config write lags process exit.
     $r = $null

benchmark/single-query-bench-claude.sh

@@ -32,6 +32,10 @@ while [ $# -gt 0 ]; do
     esac
 done
 
+# Only pass --model when one was given, so the default follows the user's Claude Code config.
+MODEL_ARGS=()
+[ -n "$MODEL" ] && MODEL_ARGS=(--model "$MODEL")
+
 CACHE_VARS="DISABLE_PROMPT_CACHING DISABLE_AUTOUPDATER ENABLE_PROMPT_CACHING_1H"
 
 # Indexed arrays are fine on bash 3.2 (macOS); associative arrays are not, so we avoid them.
@@ -173,7 +177,7 @@ invoke_run() {
     # --- Turn 1: warm-up (writes the TUI prefix into cache) --------------------------------
     echo "WARM-UP: in Claude, type  hi  and press Enter; wait for the reply, then /exit."
     pause "  Press any key to start the WARM-UP session..."
-    "$CLAUDE_BIN" --model "$MODEL" --append-system-prompt "$nonce" || true
+    "$CLAUDE_BIN" ${MODEL_ARGS[@]+"${MODEL_ARGS[@]}"} --append-system-prompt "$nonce" || true
 
     # --- Turn 2: measured (reads the prefix warm; keep it to ONE turn) ---------------------
     if copy_clip "$PROMPT"; then
@@ -185,7 +189,7 @@ invoke_run() {
         echo "Do exactly ONE turn, then /exit."
     fi
     pause "  Press any key to start the MEASURED session..."
-    "$CLAUDE_BIN" --model "$MODEL" --append-system-prompt "$nonce" || true
+    "$CLAUDE_BIN" ${MODEL_ARGS[@]+"${MODEL_ARGS[@]}"} --append-system-prompt "$nonce" || true
 
     # Read official metrics; retry in case the config write lags process exit.
     local out="" i