Introduce signals change (#655)

* adding support for signals

* reducing false positives for signals like positive interaction

* adding docs. Still need to fix the messages list, but waiting on PR #621

* Improve frustration detection: normalize contractions and refine punctuation

* Further refine test cases with longer messages

* minor doc changes

* fixing echo statement for build

* fixing the messages construction and using the trait for signals

* update signals docs

* fixed some minor doc changes

* added more tests and fixed docuemtnation. PR 100% ready

* made fixes based on PR comments

* Optimize latency

1. replace sliding window approach with trigram containment check
2. add code to pre-compute ngrams for patterns

* removed some debug statements to make tests easier to read

* PR comments to make ObservableStreamProcessor accept optonal Vec<Messagges>

* fixed PR comments

---------

Co-authored-by: Salman Paracha <salmanparacha@MacBook-Pro-342.local>
Co-authored-by: MeiyuZhong <mariazhong9612@gmail.com>
Co-authored-by: nehcgs <54548843+nehcgs@users.noreply.github.com>

crates/brightstaff/src/tracing/constants.rs

@@ -139,6 +139,45 @@ pub mod error {
     pub const STACK_TRACE: &str = "error.stack_trace";
 }
 
+// =============================================================================
+// Span Attributes - Agentic Signals
+// =============================================================================
+
+/// Behavioral quality indicators for agent interactions
+/// These signals are computed automatically from conversation patterns
+pub mod signals {
+    /// Overall quality assessment
+    /// Values: "Excellent", "Good", "Neutral", "Poor", "Severe"
+    pub const QUALITY: &str = "signals.quality";
+
+    /// Total number of turns in the conversation
+    pub const TURN_COUNT: &str = "signals.turn_count";
+
+    /// Efficiency score (0.0-1.0)
+    pub const EFFICIENCY_SCORE: &str = "signals.efficiency_score";
+
+    /// Number of repair attempts detected
+    pub const REPAIR_COUNT: &str = "signals.follow_up.repair.count";
+
+    /// Ratio of repairs to user turns
+    pub const REPAIR_RATIO: &str = "signals.follow_up.repair.ratio";
+
+    /// Number of frustration indicators detected
+    pub const FRUSTRATION_COUNT: &str = "signals.frustration.count";
+
+    /// Frustration severity level (0-3)
+    pub const FRUSTRATION_SEVERITY: &str = "signals.frustration.severity";
+
+    /// Number of repetition instances detected
+    pub const REPETITION_COUNT: &str = "signals.repetition.count";
+
+    /// Whether escalation was requested (user asked for human help)
+    pub const ESCALATION_REQUESTED: &str = "signals.escalation.requested";
+
+    /// Number of positive feedback indicators detected
+    pub const POSITIVE_FEEDBACK_COUNT: &str = "signals.positive_feedback.count";
+}
+
 // =============================================================================
 // Operation Names
 // =============================================================================

crates/brightstaff/src/tracing/mod.rs

@@ -1,3 +1,5 @@
 mod constants;
 
-pub use constants::{error, http, llm, operation_component, routing, OperationNameBuilder};
+pub use constants::{
+    error, http, llm, operation_component, routing, signals, OperationNameBuilder,
+};