fix(insights): hide cache read/write and cost metrics from display (#11477)

The cache-read, cache-write, and total estimated-cost values shown in
/insights (and the per-model Cost column) were unreliable. Hide them from
both terminal and gateway renderings.

The underlying data pipeline is untouched — sessions still store
cache_read_tokens, cache_write_tokens, and estimated_cost_usd; the web
server, /usage command, and status bar are unaffected. Only the
InsightsEngine display layer is trimmed.

Changes:
- format_terminal: drop 'Cache read / Cache write' line, drop 'Est. cost'
  from the Total tokens row, drop per-model 'Cost' column, drop the
  '* Cost N/A for custom/self-hosted' footnote.
- format_gateway: drop cache breakdown from Tokens line, drop 'Est. cost'
  line, drop per-model cost suffix.
- Tests updated to assert these strings are now absent.

agent/insights.py

@@ -634,13 +634,7 @@ class InsightsEngine:
         lines.append(f"  Sessions:          {o['total_sessions']:<12}  Messages:        {o['total_messages']:,}")
         lines.append(f"  Tool calls:        {o['total_tool_calls']:<12,}  User messages:   {o['user_messages']:,}")
         lines.append(f"  Input tokens:      {o['total_input_tokens']:<12,}  Output tokens:   {o['total_output_tokens']:,}")
-        cache_total = o.get("total_cache_read_tokens", 0) + o.get("total_cache_write_tokens", 0)
-        if cache_total > 0:
-            lines.append(f"  Cache read:        {o['total_cache_read_tokens']:<12,}  Cache write:     {o['total_cache_write_tokens']:,}")
-        cost_str = f"${o['estimated_cost']:.2f}"
-        if o.get("models_without_pricing"):
-            cost_str += " *"
-        lines.append(f"  Total tokens:      {o['total_tokens']:<12,}  Est. cost:       {cost_str}")
+        lines.append(f"  Total tokens:      {o['total_tokens']:,}")
         if o["total_hours"] > 0:
             lines.append(f"  Active time:       ~{_format_duration(o['total_hours'] * 3600):<11}  Avg session:     ~{_format_duration(o['avg_session_duration'])}")
         lines.append(f"  Avg msgs/session:  {o['avg_messages_per_session']:.1f}")
@@ -650,16 +644,10 @@ class InsightsEngine:
         if report["models"]:
             lines.append("  🤖 Models Used")
             lines.append("  " + "─" * 56)
-            lines.append(f"  {'Model':<30} {'Sessions':>8} {'Tokens':>12} {'Cost':>8}")
+            lines.append(f"  {'Model':<30} {'Sessions':>8} {'Tokens':>12}")
             for m in report["models"]:
                 model_name = m["model"][:28]
-                if m.get("has_pricing"):
-                    cost_cell = f"${m['cost']:>6.2f}"
-                else:
-                    cost_cell = "     N/A"
-                lines.append(f"  {model_name:<30} {m['sessions']:>8} {m['total_tokens']:>12,} {cost_cell}")
-            if o.get("models_without_pricing"):
-                lines.append("  * Cost N/A for custom/self-hosted models")
+                lines.append(f"  {model_name:<30} {m['sessions']:>8} {m['total_tokens']:>12,}")
             lines.append("")
 
         # Platform breakdown
@@ -739,15 +727,7 @@ class InsightsEngine:
 
         # Overview
         lines.append(f"**Sessions:** {o['total_sessions']} | **Messages:** {o['total_messages']:,} | **Tool calls:** {o['total_tool_calls']:,}")
-        cache_total = o.get("total_cache_read_tokens", 0) + o.get("total_cache_write_tokens", 0)
-        if cache_total > 0:
-            lines.append(f"**Tokens:** {o['total_tokens']:,} (in: {o['total_input_tokens']:,} / out: {o['total_output_tokens']:,} / cache: {cache_total:,})")
-        else:
-            lines.append(f"**Tokens:** {o['total_tokens']:,} (in: {o['total_input_tokens']:,} / out: {o['total_output_tokens']:,})")
-        cost_note = ""
-        if o.get("models_without_pricing"):
-            cost_note = " _(excludes custom/self-hosted models)_"
-        lines.append(f"**Est. cost:** ${o['estimated_cost']:.2f}{cost_note}")
+        lines.append(f"**Tokens:** {o['total_tokens']:,} (in: {o['total_input_tokens']:,} / out: {o['total_output_tokens']:,})")
         if o["total_hours"] > 0:
             lines.append(f"**Active time:** ~{_format_duration(o['total_hours'] * 3600)} | **Avg session:** ~{_format_duration(o['avg_session_duration'])}")
         lines.append("")
@@ -756,8 +736,7 @@ class InsightsEngine:
         if report["models"]:
             lines.append("**🤖 Models:**")
             for m in report["models"][:5]:
-                cost_str = f"${m['cost']:.2f}" if m.get("has_pricing") else "N/A"
-                lines.append(f"  {m['model'][:25]} — {m['sessions']} sessions, {m['total_tokens']:,} tokens, {cost_str}")
+                lines.append(f"  {m['model'][:25]} — {m['sessions']} sessions, {m['total_tokens']:,} tokens")
             lines.append("")
 
         # Platforms (if multi-platform)

tests/agent/test_insights.py

@@ -411,8 +411,10 @@ class TestTerminalFormatting:
 
         assert "Input tokens" in text
         assert "Output tokens" in text
-        assert "Est. cost" in text
-        assert "$" in text
+        # Cost and cache metrics are intentionally hidden (pricing was unreliable).
+        assert "Est. cost" not in text
+        assert "Cache read" not in text
+        assert "Cache write" not in text
 
     def test_terminal_format_shows_platforms(self, populated_db):
         engine = InsightsEngine(populated_db)
@@ -431,8 +433,8 @@ class TestTerminalFormatting:
 
         assert "█" in text  # Bar chart characters
 
-    def test_terminal_format_shows_na_for_custom_models(self, db):
-        """Custom models should show N/A instead of fake cost."""
+    def test_terminal_format_hides_cost_for_custom_models(self, db):
+        """Cost display is hidden entirely — custom models no longer show 'N/A' either."""
         db.create_session(session_id="s1", source="cli", model="my-custom-model")
         db.update_token_counts("s1", input_tokens=1000, output_tokens=500)
         db._conn.commit()
@@ -441,8 +443,9 @@ class TestTerminalFormatting:
         report = engine.generate(days=30)
         text = engine.format_terminal(report)
 
-        assert "N/A" in text
-        assert "custom/self-hosted" in text
+        assert "N/A" not in text
+        assert "custom/self-hosted" not in text
+        assert "Cost" not in text
 
 
 class TestGatewayFormatting:
@@ -461,13 +464,14 @@ class TestGatewayFormatting:
 
         assert "**" in text  # Markdown bold
 
-    def test_gateway_format_shows_cost(self, populated_db):
+    def test_gateway_format_hides_cost(self, populated_db):
         engine = InsightsEngine(populated_db)
         report = engine.generate(days=30)
         text = engine.format_gateway(report)
 
-        assert "$" in text
-        assert "Est. cost" in text
+        assert "$" not in text
+        assert "Est. cost" not in text
+        assert "cache" not in text.lower()
 
     def test_gateway_format_shows_models(self, populated_db):
         engine = InsightsEngine(populated_db)