remove strategy field from config

Author: ChristianPavilonis

TESTING.md

@@ -62,9 +62,8 @@ Edit `trusted-server.toml` to customize the auction:
 # Enable/disable orchestrator
 [auction]
 enabled = true
-strategy = "parallel_mediation"  # or "parallel_only"
 bidders = ["prebid", "aps"]
-mediator = "gam"
+mediator = "gam"  # If set: mediation, if omitted: highest bid wins
 timeout_ms = 2000
 
 # Mock provider configs
@@ -87,9 +86,8 @@ gam_win_rate = 30  # GAM wins 30% of the time
 ```toml
 [auction]
 enabled = true
-strategy = "parallel_mediation"
 bidders = ["prebid", "aps"]
-mediator = "gam"
+mediator = "gam"  # Mediator configured = parallel mediation strategy
 ```
 
 **Expected Flow:**
@@ -103,9 +101,8 @@ mediator = "gam"
 ```toml
 [auction]
 enabled = true
-strategy = "parallel_only"
 bidders = ["prebid", "aps"]
-# No mediator
+# No mediator = parallel only strategy
 ```
 
 **Expected Flow:**

crates/common/src/auction/README.md

@@ -402,9 +402,8 @@ Manages the execution of an auction flow, coordinates providers, and collects re
 ```toml
 [auction]
 enabled = true
-strategy = "parallel_mediation"
 bidders = ["prebid", "aps"]
-mediator = "gam"
+mediator = "gam"  # Setting mediator enables parallel mediation strategy
 timeout_ms = 2000
 ```
 
@@ -420,8 +419,8 @@ timeout_ms = 2000
 ```toml
 [auction]
 enabled = true
-strategy = "parallel_only"
 bidders = ["prebid", "aps"]
+# No mediator = parallel only strategy (highest CPM wins)
 timeout_ms = 2000
 ```
 
@@ -439,12 +438,15 @@ All auction settings are configured directly under `[auction]`:
 ```toml
 [auction]
 enabled = true                      # Enable/disable auction orchestration
-strategy = "parallel_mediation"     # Auction strategy
 bidders = ["prebid", "aps"]        # List of bidder providers
-mediator = "gam"                    # Optional mediator (only for parallel_mediation)
+mediator = "gam"                    # Optional: if set, uses mediation; if omitted, highest bid wins
 timeout_ms = 2000                   # Overall auction timeout
 ```
 
+**Strategy Auto-Detection:**
+- When `mediator` is configured → Runs **parallel mediation** (bidders in parallel, mediator decides winner)
+- When `mediator` is omitted → Runs **parallel only** (bidders in parallel, highest CPM wins)
+
 ### Provider Configuration
 
 Each provider has its own configuration section:

crates/common/src/auction/mod.rs

@@ -385,12 +385,19 @@ fn convert_to_openrtb_response(
         }));
     }
 
+    // Determine strategy name for response metadata
+    let strategy_name = if settings.auction.has_mediator() {
+        "parallel_mediation"
+    } else {
+        "parallel_only"
+    };
+
     let response_body = json!({
         "id": auction_id,
         "seatbid": seatbids,
         "ext": {
             "orchestrator": {
-                "strategy": settings.auction.strategy,
+                "strategy": strategy_name,
                 "bidders": result.bidder_responses.len(),
                 "total_bids": result.total_bids(),
                 "time_ms": result.total_time_ms

crates/common/src/auction/orchestrator.rs

@@ -38,26 +38,35 @@ impl AuctionOrchestrator {
         self.providers.len()
     }
 
-    /// Execute an auction using the configured strategy.
+    /// Execute an auction using the auto-detected strategy.
+    ///
+    /// Strategy is determined by mediator configuration:
+    /// - If mediator is configured: runs parallel mediation (bidders → mediator decides)
+    /// - If no mediator: runs parallel only (bidders → highest CPM wins)
     pub async fn run_auction(
         &self,
         request: &AuctionRequest,
         context: &AuctionContext<'_>,
     ) -> Result<OrchestrationResult, Report<TrustedServerError>> {
         let start_time = Instant::now();
 
-        log::info!("Running auction with strategy: {}", self.config.strategy);
+        // Auto-detect strategy based on mediator configuration
+        let (strategy_name, result) = if self.config.has_mediator() {
+            (
+                "parallel_mediation",
+                self.run_parallel_mediation(request, context).await?,
+            )
+        } else {
+            (
+                "parallel_only",
+                self.run_parallel_only(request, context).await?,
+            )
+        };
 
-        let result = match self.config.strategy.as_str() {
-            "parallel_mediation" => self.run_parallel_mediation(request, context).await,
-            "parallel_only" => self.run_parallel_only(request, context).await,
-            strategy => Err(Report::new(TrustedServerError::Auction {
-                message: format!(
-                    "Unknown auction strategy '{}'. Valid strategies: parallel_mediation, parallel_only",
-                    strategy
-                ),
-            })),
-        }?;
+        log::info!(
+            "Running auction with strategy: {} (auto-detected from mediator config)",
+            strategy_name
+        );
 
         Ok(OrchestrationResult {
             total_time_ms: start_time.elapsed().as_millis() as u64,
@@ -429,7 +438,6 @@ mod tests {
     async fn test_no_bidders_configured() {
         let config = AuctionConfig {
             enabled: true,
-            strategy: "parallel_only".to_string(),
             bidders: vec![],
             mediator: None,
             timeout_ms: 2000,

crates/common/src/auction_config_types.rs

@@ -9,16 +9,14 @@ pub struct AuctionConfig {
     #[serde(default)]
     pub enabled: bool,
 
-    /// Auction strategy: "parallel_mediation", "parallel_only"
-    #[serde(default = "default_strategy")]
-    pub strategy: String,
-
     /// Provider names that participate in bidding
     /// Simply list the provider names (e.g., ["prebid", "aps"])
     #[serde(default)]
     pub bidders: Vec<String>,
 
     /// Optional mediator provider name (e.g., "gam")
+    /// When set, runs parallel mediation strategy (bidders in parallel, then mediator decides)
+    /// When omitted, runs parallel only strategy (bidders in parallel, highest CPM wins)
     pub mediator: Option<String>,
 
     /// Timeout in milliseconds
@@ -30,10 +28,6 @@ pub struct AuctionConfig {
     pub creative_store: String,
 }
 
-fn default_strategy() -> String {
-    "parallel_mediation".to_string()
-}
-
 fn default_timeout() -> u32 {
     2000
 }

crates/common/src/integrations/aps_readme.md

@@ -60,9 +60,9 @@ Run APS alongside other bidders:
 ```toml
 [auction]
 enabled = true
-strategy = "parallel_only"
 bidders = ["aps", "prebid"]
 timeout_ms = 2000
+# No mediator = parallel only (highest CPM wins)
 ```
 
 **Benefits:**
@@ -77,9 +77,8 @@ Use GAM to mediate all bids:
 ```toml
 [auction]
 enabled = true
-strategy = "parallel_mediation"
 bidders = ["aps", "prebid"]
-mediator = "gam"
+mediator = "gam"  # Enables parallel mediation (GAM decides winner)
 timeout_ms = 2000
 ```
 

docs/APS_QUICKSTART.md

@@ -87,8 +87,8 @@ INFO APS returned 2 bids in 150ms
 ```toml
 [auction]
 enabled = true
-strategy = "parallel_only"
 bidders = ["aps"]
+# No mediator = parallel only (highest CPM wins)
 ```
 
 ### APS + Prebid (Parallel)
@@ -98,9 +98,9 @@ Best for maximum revenue:
 ```toml
 [auction]
 enabled = true
-strategy = "parallel_only"
 bidders = ["aps", "prebid"]
 timeout_ms = 2000
+# No mediator = all bidders compete, highest CPM wins
 
 [integrations.aps]
 enabled = true
@@ -120,9 +120,8 @@ Let GAM decide winners:
 ```toml
 [auction]
 enabled = true
-strategy = "parallel_mediation"
 bidders = ["aps", "prebid"]
-mediator = "gam"
+mediator = "gam"  # Setting mediator enables parallel mediation
 ```
 
 ## Testing Without Live Credentials

trusted-server.toml

@@ -72,9 +72,8 @@ rewrite_sdk = true
 # Auction orchestration configuration
 [auction]
 enabled = true
-strategy = "parallel_mediation"  # Options: "parallel_mediation", "parallel_only"
 bidders = ["prebid", "aps_mock"]  # Use mock providers for testing
-mediator = "gam_mock"
+mediator = "gam_mock"             # When set: parallel mediation, when omitted: parallel only
 timeout_ms = 2000
 
 # Mock APS Configuration (for testing)