feat: add context pressure and cost velocity MCP tools, friction patterns

Wire get_context_pressure and get_cost_velocity tool registrations,
deduplicate mkAssistantWithUsage test helper from parallel agent merge,
add friction pattern classification to get_live_friction response.

Author: blackwell-systems

CHANGELOG.md

@@ -4,6 +4,14 @@ All notable changes to claudewatch are documented here.
 
 ## [Unreleased]
 
+### Added
+
+- **`get_context_pressure`** — context window usage tracker for the current live session. Sums input/output tokens, counts compaction events, estimates usage ratio against 200k window. Status levels: "comfortable" (<50%), "filling" (50-75%), "pressure" (75-90%), "critical" (>=90%).
+
+- **`get_cost_velocity`** — cost burn rate for the current live session over a 10-minute sliding window. Computes per-minute USD spend from token counts and Sonnet pricing. Status levels: "efficient" (<$0.05/min), "normal" ($0.05-0.20/min), "burning" (>=$0.20/min).
+
+- **Friction pattern classification** — `get_live_friction` now includes a `patterns` field that collapses raw friction events into typed groups with counts, consecutive run detection, and first/last turn references. Sorted by frequency for quick triage.
+
 ## [0.7.0] - 2026-03-02
 
 ### Added

docs/IMPL-push-observability.md

@@ -629,7 +629,7 @@ After Wave 1 completes (all 4 agents):
 - [x] Wave 1 Agent B -- `get_context_pressure` MCP tool
 - [x] Wave 1 Agent C -- `get_cost_velocity` MCP tool
 - [x] Wave 1 Agent D -- Friction pattern classification
-- [ ] Post-merge -- Register tools in `tools.go`, fix test counts
+- [x] Post-merge -- Register tools in `tools.go`, deduplicate `mkAssistantWithUsage` test helper (B/C collision), all tests pass
 
 ---
 

internal/claude/active_live.go

@@ -29,11 +29,11 @@ type LiveFrictionEvent struct {
 
 // FrictionPattern represents a grouped friction pattern collapsed from individual events.
 type FrictionPattern struct {
-	Type        string `json:"type"`         // e.g. "tool_error:Edit", "retry:Bash"
-	Count       int    `json:"count"`        // total occurrences
-	Consecutive bool   `json:"consecutive"`  // true if all occurrences were consecutive
-	FirstTurn   int    `json:"first_turn"`   // position of first occurrence in events slice
-	LastTurn    int    `json:"last_turn"`    // position of last occurrence
+	Type        string `json:"type"`        // e.g. "tool_error:Edit", "retry:Bash"
+	Count       int    `json:"count"`       // total occurrences
+	Consecutive bool   `json:"consecutive"` // true if all occurrences were consecutive
+	FirstTurn   int    `json:"first_turn"`  // position of first occurrence in events slice
+	LastTurn    int    `json:"last_turn"`   // position of last occurrence
 }
 
 // LiveFrictionStats holds friction statistics parsed from a live JSONL session.

internal/claude/active_live_cost_test.go

@@ -1,31 +1,12 @@
 package claude
 
 import (
-	"encoding/json"
-	"fmt"
 	"os"
 	"path/filepath"
 	"testing"
 	"time"
 )
 
-// mkAssistantWithUsage builds a JSONL entry for an assistant message with token usage.
-func mkAssistantWithUsage(ts string, inputTokens, outputTokens int) map[string]any {
-	msg, _ := json.Marshal(map[string]any{
-		"role":    "assistant",
-		"content": []map[string]any{},
-		"usage": map[string]any{
-			"input_tokens":  inputTokens,
-			"output_tokens": outputTokens,
-		},
-	})
-	return map[string]any{
-		"type":      "assistant",
-		"timestamp": ts,
-		"message":   json.RawMessage(msg),
-	}
-}
-
 func TestParseLiveCostVelocity_EmptyFile(t *testing.T) {
 	dir := t.TempDir()
 	path := filepath.Join(dir, "empty.jsonl")
@@ -172,8 +153,8 @@ func TestParseLiveCostVelocity_MixedWindowEntries(t *testing.T) {
 	recentTS := time.Now().Add(-2 * time.Minute).UTC().Format(time.RFC3339)
 
 	path := writeLiveJSONL(t, []map[string]any{
-		mkAssistantWithUsage(oldTS, 5_000_000, 1_000_000),   // outside window
-		mkAssistantWithUsage(recentTS, 100_000, 10_000),     // inside window
+		mkAssistantWithUsage(oldTS, 5_000_000, 1_000_000), // outside window
+		mkAssistantWithUsage(recentTS, 100_000, 10_000),   // inside window
 	})
 
 	pricing := CostPricing{InputPerMillion: 3.0, OutputPerMillion: 15.0}
@@ -188,5 +169,4 @@ func TestParseLiveCostVelocity_MixedWindowEntries(t *testing.T) {
 		t.Fatalf("expected WindowCostUSD~%f, got %f", expectedCost, stats.WindowCostUSD)
 	}
 
-	_ = fmt.Sprintf("") // suppress unused import
 }

internal/claude/active_live_test.go

@@ -457,9 +457,9 @@ func TestCollapseFrictionPatterns_MixedTypes(t *testing.T) {
 
 func TestCollapseFrictionPatterns_ConsecutiveDetection(t *testing.T) {
 	events := []LiveFrictionEvent{
-		{Type: "tool_error", Tool: "Edit", Count: 1},  // idx 0
-		{Type: "retry", Tool: "Bash", Count: 2},        // idx 1
-		{Type: "tool_error", Tool: "Edit", Count: 1},  // idx 2 — gap (retry:Bash at idx 1)
+		{Type: "tool_error", Tool: "Edit", Count: 1}, // idx 0
+		{Type: "retry", Tool: "Bash", Count: 2},      // idx 1
+		{Type: "tool_error", Tool: "Edit", Count: 1}, // idx 2 — gap (retry:Bash at idx 1)
 	}
 	patterns := collapseFrictionPatterns(events)
 

internal/mcp/tools.go

@@ -149,6 +149,8 @@ func addTools(s *Server) {
 	addCostTools(s)
 	addVelocityTools(s)
 	addLiveTools(s)
+	addContextTools(s)
+	addCostVelocityTools(s)
 	s.registerTool(toolDef{
 		Name:        "get_project_comparison",
 		Description: "All projects compared side by side in a single call. Returns a ranked list of all projects with health score, friction rate, has_claude_md, agent success rate, and session count.",