fix: stop shrinking conversations behind the user's back — both automatic context guards ship off

The shipped default combined a sliding history window with no compaction, which is the worse of the two available trades in both directions it is measured on. `max_history_messages: 30` is a sliding tail window (`projection::window` — `drain(..len - max)`). Past 30 messages it drops from the head on *every* turn, so the prompt prefix changes on every single request and every provider that caches one (Anthropic breakpoints, OpenAI automatic prefix caching) misses every time. It also drops those messages with no summary standing in for them: silent amnesia, not just a cold cache. Compaction rewrites the prefix once per compaction and leaves a summary behind — yet it was the half that was commented out, while the window's own doc-comment already said the two were exclusive. Both are now `Option` and both ship unset, so nothing shrinks a conversation unless a human types `/compact`. Which surfaced the real bug: `/compact` did not work either. The compactor was `Option<Arc<ContextCompactor>>` keyed on the config section existing, so commenting out `compaction:` disabled the manual command too — `force_compact` returned `Ok(false)` and the chat answered "compaction disabled". Manual compaction is a command a user types; it cannot depend on an admin having filled in a token threshold. The compactor is now built unconditionally and `threshold_tokens: Option<u32>` arms only the automatic pass; `try_compact` early-returns without it, `force_compact` deliberately never consults it. The projection accordingly yields to the *automatic* pass rather than to the compactor's existence (`LoopConfig.auto_compaction_enabled`), so a configured message cap is not silently voided by `/compact` merely being available. `CompactionConfig::Default` is hand-written for the same reason `RoleAttrs`'s is: a derived one gives `keep_recent: 0`, which would compact away every recent message on any box omitting the section — now the default. Also fixes two documentation bugs in the same file: `event_triage` was documented nested under `llm:`, where it parses fine and is then silently ignored (it is a top-level field), and `datetime` was documented twice with conflicting examples. A new test asserts the shipped default actually deserializes and that both guards are off — a field the default omits must be genuinely optional, or a brand-new install fails to boot. Automatic compaction returns later, triggered off the resolved model's own context window instead of a hand-tuned token count that cannot know which model is answering.
2026-08-02 21:21:14 +01:00
parent d4b34e6130
commit baf68878e4
16 changed files with 227 additions and 105 deletions
@@ -329,23 +329,28 @@ impl Conversation {
        }
        info!("run_context manager ready");

-        let compactor = config.llm.compaction.as_ref().map(|cfg| {
-            info!(
-                threshold_tokens = cfg.threshold_tokens,
-                keep_recent      = cfg.keep_recent,
-                ?cfg.strength,
-                "context compactor enabled"
-            );
+        // Always built: `/compact` is a manual command and must work with no
+        // configuration. Only the automatic trigger is opt-in (`threshold_tokens`).
+        let compactor = {
+            let cfg = &config.llm.compaction;
+            match cfg.threshold_tokens {
+                Some(threshold_tokens) => info!(
+                    threshold_tokens,
+                    keep_recent = cfg.keep_recent,
+                    ?cfg.strength,
+                    "context compactor ready (automatic compaction enabled)"
+                ),
+                None => info!(
+                    "context compactor ready (automatic compaction off — /compact only)"
+                ),
+            }
            Arc::new(ContextCompactor::new(
                cfg.clone(),
                Arc::clone(&models.llm_manager),
                Arc::clone(&rt.event_bus),
                Arc::clone(&rt.config),
            ))
-        });
-        if compactor.is_none() {
-            info!("context compactor disabled (no compaction config)");
-        }
+        };

        // The ownerless manager is inert (no loops, no consumers — see §19): it takes
        // a placeholder UserFs purely to satisfy the type, never used to resolve a path.