refactor(logging): partition the log stream by session — session.log per session, daemon.log sparse, OTEL the union (#1472)

feeds/skills/.system/files/netclaw-operations/references/diagnostics.md

@@ -34,16 +34,20 @@ What to expect inside `session.log`:
   cross-referencing two files.
 - Two line shapes: session output audit lines (`User:`, `Assistant:`,
   `Thinking:`, `Tool call:`, `Tool result:`, `Usage:`, `Turn N completed`,
-  etc.) and `Diagnostic:` lines from MEL providers (LLM client, HTTP,
-  retry middleware) emitted under a session diagnostics scope.
+  etc.) and `Diagnostic:` lines. Diagnostic lines reach `session.log` only
+  when a producer *explicitly publishes* them — notably the sub-agent spawn
+  lifecycle (requested, child spawned, dispatched, completed/failed, and
+  guard rejections), so a failed or blocked spawn is visible here. It is an
+  explicit publish, not automatic routing of every log line.
 - Best-effort observability. Individual lines may be dropped on transient
   IO errors and logged at Debug level in the daemon log; this is not a
   transactional audit trail. Cross-check the daemon log for warnings
   if a critical line appears missing.
-- Sidecar paths (compaction, title generation, sub-agents, memory
-  distillation) currently bypass the session diagnostics scope, so their
-  internal diagnostics may not appear in `session.log` even though their
-  output audit lines do. Tracked in netclaw-dev/netclaw#920.
+- Most actor and operational logs are NOT in `session.log` — only explicitly
+  published lines are. An actor's own lifecycle logging, and the LLM-client /
+  HTTP / retry / failover decorator internals, go to `daemon.log` (filterable
+  by the `SessionId` structured field where the line carries one). For an
+  actor's full lifecycle or deep LLM-call internals, read `daemon.log`.
 
 | Symptom | Check |
 |---------|-------|

src/Netclaw.Configuration.Tests/SessionDiagnosticsContextTests.cs → src/Netclaw.Actors.Tests/SubAgents/SubAgentSessionScopeTests.cs

@@ -1,22 +1,22 @@
 // -----------------------------------------------------------------------
-// <copyright file="SessionDiagnosticsContextTests.cs" company="Petabridge, LLC">
+// <copyright file="SubAgentSessionScopeTests.cs" company="Petabridge, LLC">
 //      Copyright (C) 2026 - 2026 Petabridge, LLC <https://petabridge.com>
 // </copyright>
 // -----------------------------------------------------------------------
-using Netclaw.Configuration;
+using Netclaw.Actors.SubAgents;
 using Xunit;
 
-namespace Netclaw.Configuration.Tests;
+namespace Netclaw.Actors.Tests.SubAgents;
 
-public sealed class SessionDiagnosticsContextTests
+public sealed class SubAgentSessionScopeTests
 {
     [Theory]
     [InlineData("ch/thr/subagent/skill", "ch/thr")]
     [InlineData("ch/thr", "ch/thr")]
     [InlineData("ch/thr/subagent/skill/inner", "ch/thr")]
     public void NormalizeSessionId_collapses_subagent_marker_to_parent_id(string input, string expected)
     {
-        Assert.Equal(expected, SessionDiagnosticsContext.NormalizeSessionId(input));
+        Assert.Equal(expected, SubAgentSessionScope.NormalizeSessionId(input));
     }
 
     [Theory]
@@ -25,6 +25,6 @@ public void NormalizeSessionId_collapses_subagent_marker_to_parent_id(string inp
     [InlineData("   ")]
     public void NormalizeSessionId_returns_null_for_blank(string? input)
     {
-        Assert.Null(SessionDiagnosticsContext.NormalizeSessionId(input));
+        Assert.Null(SubAgentSessionScope.NormalizeSessionId(input));
     }
 }