fix(923): watchdog counts only tool-using turns; narration-only turns no longer burn budget

Observed: stories 917, 918, 920, 910 all turn-limit-killed despite producing
real commits. Tally across their session logs shows 30–55% of assistant
turns were pure narration ("I'll read X next", "Now let me check Y") with
no tool_use. At 80 max_turns the effective work budget was ~44 tool calls,
not enough for a typical bug fix's edit + test + check_criterion cycle.

Changes:
- New optional AgentConfig field max_tool_turns. When set the watchdog
  uses it instead of max_turns; only assistant messages whose
  data.message.content has at least one tool_use block count.
- count_turns_in_log in agents/pool/auto_assign/watchdog/limits.rs
  filters on tool_use. Existing test helper write_fake_session_log now
  emits tool_use blocks; added write_fake_mixed_session_log for the
  narration regression test.
- agents.toml: coders/coder-opus get max_turns=200 (claude-code's own
  --max-turns cap, sized to never bite before the watchdog) and
  max_tool_turns=80. qa: 120 / 40. mergemaster: 250 / 100. Budgets
  unchanged — the dollar cap remains the runaway-loop backstop, with
  ~$3-5 worst-case waste if an agent narrates indefinitely.
- Two new regression tests:
  * watchdog_does_not_count_narration_only_turns: 5 tool + 30 narration
    under max_tool_turns=10 stays Running.
  * watchdog_max_tool_turns_overrides_max_turns: 4 tool turns at
    max_tool_turns=3 / max_turns=200 still terminates with TurnLimit.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

server/src/agents/pool/auto_assign/watchdog/tests/mod.rs

@@ -5,29 +5,75 @@ use std::path::Path;
 mod limits_tests;
 mod orphan_tests;
 
-/// Write a fake session log file with `n` assistant turn entries.
+/// Write a fake session log file with `n` tool-using assistant turn entries.
 ///
-/// The file is named `{agent_name}-{session_id}.log` to match the
-/// real naming convention used by `AgentLogWriter`.
+/// Each turn includes a single `tool_use` content block so it counts under
+/// the watchdog's tool-only turn filter (story 923). The file is named
+/// `{agent_name}-{session_id}.log` to match the real naming convention
+/// used by `AgentLogWriter`.
 pub(super) fn write_fake_session_log(
     project_root: &Path,
     story_id: &str,
     agent_name: &str,
     session_id: &str,
     n_turns: u64,
+) {
+    write_fake_mixed_session_log(project_root, story_id, agent_name, session_id, n_turns, 0);
+}
+
+/// Write a fake session log with `n_tool` tool-using assistant turns and
+/// `n_narration` text-only narration turns (story 923 regression).
+///
+/// Tool turns contain a `tool_use` content block; narration turns contain
+/// only a `text` block. The watchdog's `count_turns_in_log` must report
+/// `n_tool` only — narration must not count.
+pub(super) fn write_fake_mixed_session_log(
+    project_root: &Path,
+    story_id: &str,
+    agent_name: &str,
+    session_id: &str,
+    n_tool: u64,
+    n_narration: u64,
 ) {
     let log_dir = project_root.join(".huskies").join("logs").join(story_id);
     std::fs::create_dir_all(&log_dir).unwrap();
     let log_path = log_dir.join(format!("{agent_name}-{session_id}.log"));
     let mut content = String::new();
-    for _ in 0..n_turns {
+    for _ in 0..n_tool {
         content.push_str(
             &serde_json::to_string(&serde_json::json!({
                 "timestamp": "2026-04-25T00:00:00Z",
                 "type": "agent_json",
                 "story_id": story_id,
                 "agent_name": agent_name,
-                "data": { "type": "assistant", "message": {} }
+                "data": {
+                    "type": "assistant",
+                    "message": {
+                        "content": [
+                            { "type": "tool_use", "name": "Read", "input": {} }
+                        ]
+                    }
+                }
+            }))
+            .unwrap(),
+        );
+        content.push('\n');
+    }
+    for _ in 0..n_narration {
+        content.push_str(
+            &serde_json::to_string(&serde_json::json!({
+                "timestamp": "2026-04-25T00:00:00Z",
+                "type": "agent_json",
+                "story_id": story_id,
+                "agent_name": agent_name,
+                "data": {
+                    "type": "assistant",
+                    "message": {
+                        "content": [
+                            { "type": "text", "text": "Now let me read the next file." }
+                        ]
+                    }
+                }
             }))
             .unwrap(),
         );