feat: make tool result pruning opt-in

crates/manifest/src/config.rs

@@ -577,6 +577,8 @@ pub struct PermissionConfigPartial {
 
 #[derive(Debug, Clone, Default, Serialize, Deserialize)]
 pub struct CompactionConfigPartial {
+    #[serde(default)]
+    pub prune_enabled: Option<bool>,
     #[serde(default)]
     pub prune_protected_tokens: Option<u64>,
     #[serde(default)]
@@ -912,6 +914,7 @@ impl PermissionConfigPartial {
 impl CompactionConfigPartial {
     fn merge(self, upper: Self) -> Self {
         Self {
+            prune_enabled: upper.prune_enabled.or(self.prune_enabled),
             prune_protected_tokens: upper.prune_protected_tokens.or(self.prune_protected_tokens),
             prune_min_savings: upper.prune_min_savings.or(self.prune_min_savings),
             threshold: upper.threshold.or(self.threshold),
@@ -1223,6 +1226,7 @@ impl TryFrom<WorkerManifestConfig> for WorkerManifest {
                     validate_model_paths(cm, "compaction.model.auth.file")?;
                 }
                 Ok(CompactionConfig {
+                    prune_enabled: c.prune_enabled.unwrap_or(defaults::PRUNE_ENABLED),
                     prune_protected_tokens: c
                         .prune_protected_tokens
                         .unwrap_or(defaults::PRUNE_PROTECTED_TOKENS),
@@ -1831,6 +1835,7 @@ mod tests {
         let lower = WorkerManifestConfig {
             compaction: Some(CompactionConfigPartial {
                 threshold: Some(50_000),
+                prune_enabled: Some(false),
                 prune_protected_tokens: Some(5_000),
                 ..Default::default()
             }),
@@ -1861,7 +1866,8 @@ mod tests {
         let merged = lower.merge(upper);
         let c = merged.compaction.unwrap();
         assert_eq!(c.threshold, Some(80_000));
-        // field from lower retained when upper has None
+        // fields from lower retained when upper has None
+        assert_eq!(c.prune_enabled, Some(false));
         assert_eq!(c.prune_protected_tokens, Some(5_000));
         let search = merged.web.unwrap().search.unwrap();
         assert_eq!(search.timeout_secs, Some(3));

crates/manifest/src/defaults.rs

@@ -14,6 +14,10 @@ pub const TOOL_OUTPUT_MAX_BYTES: usize = 64 * 1024;
 /// See [`crate::FileUploadLimits`].
 pub const FILE_UPLOAD_MAX_BYTES: usize = 256 * 1024;
 
+/// Whether request-time tool-result pruning is enabled when `[compaction]`
+/// exists. See [`crate::CompactionConfig::prune_enabled`].
+pub const PRUNE_ENABLED: bool = false;
+
 /// Token budget at the history tail protected from pruning. See
 /// [`crate::CompactionConfig::prune_protected_tokens`].
 pub const PRUNE_PROTECTED_TOKENS: u64 = 8000;

crates/manifest/src/lib.rs

@@ -768,6 +768,11 @@ pub enum ToolPermissionAction {
 /// (full history summarisation). Omitting `[compaction]` disables both.
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct CompactionConfig {
+    /// Whether request-time projection removes detail from old tool results.
+    /// Independent from the compaction thresholds below.
+    #[serde(default = "default_prune_enabled")]
+    pub prune_enabled: bool,
+
     /// Token budget at the history tail protected from pruning.
     #[serde(default = "default_prune_protected_tokens")]
     pub prune_protected_tokens: u64,
@@ -868,6 +873,9 @@ pub struct CompactionConfig {
     pub model: Option<ModelManifest>,
 }
 
+fn default_prune_enabled() -> bool {
+    defaults::PRUNE_ENABLED
+}
 fn default_prune_protected_tokens() -> u64 {
     defaults::PRUNE_PROTECTED_TOKENS
 }
@@ -914,6 +922,7 @@ fn default_result_context_max_tokens() -> u64 {
 impl Default for CompactionConfig {
     fn default() -> Self {
         Self {
+            prune_enabled: default_prune_enabled(),
             prune_protected_tokens: default_prune_protected_tokens(),
             prune_min_savings: default_prune_min_savings(),
             threshold: None,
@@ -1460,9 +1469,11 @@ model_id = "claude-sonnet-4-20250514"
 
     #[test]
     fn parse_compaction_config() {
-        let toml = format!("{MINIMAL_REQUIRED}\n[compaction]\nthreshold = 80000\n");
+        let toml =
+            format!("{MINIMAL_REQUIRED}\n[compaction]\nprune_enabled = false\nthreshold = 80000\n");
         let manifest = WorkerManifest::from_toml(&toml).unwrap();
         let c = manifest.compaction.unwrap();
+        assert!(!c.prune_enabled);
         assert_eq!(c.prune_protected_tokens, 8000);
         assert_eq!(c.prune_min_savings, 4096);
         assert_eq!(c.threshold, Some(80000));
@@ -1471,6 +1482,11 @@ model_id = "claude-sonnet-4-20250514"
         assert_eq!(c.worker_max_turns, Some(20));
     }
 
+    #[test]
+    fn compaction_defaults_to_pruning_disabled() {
+        assert!(!CompactionConfig::default().prune_enabled);
+    }
+
     #[test]
     fn reject_removed_prune_protected_turns_field() {
         let toml = format!("{MINIMAL_REQUIRED}\n[compaction]\nprune_protected_turns = 3\n");

crates/manifest/src/profile.rs

@@ -1245,6 +1245,26 @@ mod tests {
                 .unwrap()
         };
 
+        for name in [
+            "default",
+            "intake",
+            "orchestrator",
+            "companion",
+            "coder",
+            "reviewer",
+            "memory-consolidation",
+        ] {
+            let role = resolve(name);
+            assert_eq!(
+                role.manifest
+                    .compaction
+                    .as_ref()
+                    .map(|compaction| compaction.prune_enabled),
+                Some(false),
+                "{name} must keep pruning disabled for the experiment"
+            );
+        }
+
         let companion = resolve("companion");
         assert_eq!(
             companion.manifest.model.ref_.as_deref(),