diff --git a/src/app.rs b/src/app.rs
index 3471c9c..891b3e1 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -1408,8 +1408,10 @@ impl App {
         let name = s.name.clone();
         let kind = s.kind.label().to_string();
         let waiting_prompt = s.waiting_prompt.clone();
-        let tail = pipe::extract_from_session(&self.sessions, session_id, &ExtractMode::LastN(15))
-            .unwrap_or_default();
+        let tail_n = self.config.orchestrator.event_tail_lines.max(1);
+        let tail =
+            pipe::extract_from_session(&self.sessions, session_id, &ExtractMode::LastN(tail_n))
+                .unwrap_or_default();
 
         if let Some(h) = &self.orchestrator {
             // try_send: a wedged orchestrator must never block the main loop.
@@ -2061,6 +2063,20 @@ impl App {
                     }
                 })
                 .unwrap_or_default();
+            // Cap the reply so a chatty session can't dump its whole
+            // transcript into the orchestrator's context in one tool result.
+            let max = self.config.orchestrator.wait_ready_max_lines;
+            let lines = if max > 0 && lines.len() > max {
+                let total = lines.len();
+                let mut kept: Vec<String> = lines[total - max..].to_vec();
+                kept.insert(
+                    0,
+                    format!("[truncated: showing last {} of {} lines]", max, total),
+                );
+                kept
+            } else {
+                lines
+            };
             let _ = resp_tx.send(serde_json::json!({
                 "session_id": session_id,
                 "lines": lines,
diff --git a/src/config.rs b/src/config.rs
index cd083bc..52d1c0b 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -101,6 +101,21 @@ pub struct OrchestratorConfig {
     pub max_tokens: u32,
     pub max_tool_iterations: usize,
     pub input_wait_timeout_secs: u64,
+    /// Soft token budget for the conversation history, estimated at ~4
+    /// chars/token. When the estimate exceeds this, oldest turns are dropped
+    /// even if max_history_turns hasn't been reached. 0 disables.
+    pub max_context_tokens: usize,
+    /// How many recent user turns keep their tool results verbatim. Tool
+    /// results older than this are replaced with a short elision stub (the
+    /// model can re-run the tool if it still needs the data). 0 disables.
+    pub tool_result_keep_turns: usize,
+    /// Lines of session output inlined into a [linkshell event]
+    /// notification. The orchestrator can always read_output for more.
+    pub event_tail_lines: usize,
+    /// Cap on lines returned by send_input wait_ready / `input --wait`.
+    /// Longer replies are truncated to the last N lines with a marker.
+    /// 0 disables.
+    pub wait_ready_max_lines: usize,
 }
 
 impl Default for OrchestratorConfig {
@@ -139,6 +154,10 @@ impl Default for OrchestratorConfig {
             max_tokens: 4096,
             max_tool_iterations: 12,
             input_wait_timeout_secs: 180,
+            max_context_tokens: 60_000,
+            tool_result_keep_turns: 3,
+            event_tail_lines: 5,
+            wait_ready_max_lines: 80,
         }
     }
 }
diff --git a/src/orchestrator/anthropic.rs b/src/orchestrator/anthropic.rs
index 8e2cc32..88862a6 100644
--- a/src/orchestrator/anthropic.rs
+++ b/src/orchestrator/anthropic.rs
@@ -4,6 +4,32 @@ use crate::config::OrchestratorConfig;
 use crate::events::AppEvent;
 use tokio::sync::mpsc;
 
+/// Clone the history for one request, attaching an ephemeral cache_control
+/// breakpoint to the final content block of the last message. The stored
+/// history is left untouched (trim_history relies on plain-string user
+/// turns), and the last message at request time is always a user message
+/// (fresh user text or tool_results), both of which accept cache_control.
+fn messages_with_cache_breakpoint(history: &[serde_json::Value]) -> serde_json::Value {
+    let mut msgs: Vec<serde_json::Value> = history.to_vec();
+    if let Some(last) = msgs.last_mut() {
+        let ce = serde_json::json!({"type": "ephemeral"});
+        let content = last["content"].take();
+        last["content"] = match content {
+            serde_json::Value::String(text) => {
+                serde_json::json!([{"type": "text", "text": text, "cache_control": ce}])
+            }
+            serde_json::Value::Array(mut blocks) => {
+                if let Some(b) = blocks.last_mut() {
+                    b["cache_control"] = ce;
+                }
+                serde_json::Value::Array(blocks)
+            }
+            other => other,
+        };
+    }
+    serde_json::Value::Array(msgs)
+}
+
 /// Run one conversation turn: append the user text, loop through tool calls,
 /// return the final assistant text. History uses the Messages API shape and
 /// assistant content (including thinking blocks) is replayed verbatim.
@@ -22,11 +48,22 @@ pub async fn run_turn(
         )
     })?;
     let url = format!("{}/v1/messages", cfg.endpoint_url().trim_end_matches('/'));
-    let tools = super::anthropic_tools();
-    let system = super::system_prompt(cfg);
+    // Prompt caching: mark the static prefix (tools + system) once, and put
+    // a moving breakpoint on the last message of each request so the 12
+    // iterations of a busy turn re-serve the shared history prefix instead
+    // of re-billing it in full every call.
+    let mut tools = super::anthropic_tools();
+    if let Some(last) = tools.as_array_mut().and_then(|a| a.last_mut()) {
+        last["cache_control"] = serde_json::json!({"type": "ephemeral"});
+    }
+    let system = serde_json::json!([{
+        "type": "text",
+        "text": super::system_prompt(cfg),
+        "cache_control": {"type": "ephemeral"}
+    }]);
 
     history.push(serde_json::json!({"role": "user", "content": user_text}));
-    super::trim_history(history, cfg.max_history_turns);
+    super::compact_history(history, cfg);
 
     for i in 0..cfg.max_tool_iterations {
         if interrupt.hit() {
@@ -42,7 +79,7 @@ pub async fn run_turn(
             "max_tokens": cfg.max_tokens,
             "system": system,
             "tools": tools,
-            "messages": history,
+            "messages": messages_with_cache_breakpoint(history),
         });
         let resp: serde_json::Value = auth
             .apply(client.post(&url))
@@ -135,7 +172,7 @@ pub async fn run_turn(
         "system": system,
         "tools": tools,
         "tool_choice": {"type": "none"},
-        "messages": history,
+        "messages": messages_with_cache_breakpoint(history),
     });
     let resp: serde_json::Value = auth
         .apply(client.post(&url))
diff --git a/src/orchestrator/mod.rs b/src/orchestrator/mod.rs
index b838c17..0aeca83 100644
--- a/src/orchestrator/mod.rs
+++ b/src/orchestrator/mod.rs
@@ -783,6 +783,98 @@ fn skills_section(cfg: &OrchestratorConfig, with_paths: bool) -> Option<String>
     Some(skills::skill_list(&list, with_paths))
 }
 
+/// Stub text substituted for aged-out tool results.
+const ELIDED_RESULT: &str =
+    "[elided to save context — re-run the tool if this result is still needed]";
+
+/// Count plain user-text turns (the boundaries trim_history cuts at).
+fn user_turns(history: &[serde_json::Value]) -> usize {
+    history
+        .iter()
+        .filter(|m| m["role"] == "user" && m["content"].is_string())
+        .count()
+}
+
+/// Rough token estimate for the serialized history (~4 chars/token).
+fn estimate_tokens(history: &[serde_json::Value]) -> usize {
+    history
+        .iter()
+        .map(|m| m.to_string().chars().count())
+        .sum::<usize>()
+        / 4
+}
+
+/// Replace tool results older than the last `keep_turns` plain user turns
+/// with a short stub. Structure stays API-valid for both providers: the
+/// anthropic shape keeps its tool_result blocks (ids intact) with stubbed
+/// content, the openai shape keeps its role:"tool" messages likewise.
+fn age_tool_results(history: &mut [serde_json::Value], keep_turns: usize) {
+    if keep_turns == 0 {
+        return;
+    }
+    // Index of the keep_turns-th plain user turn from the end; everything
+    // before it is "old".
+    let mut seen = 0;
+    let mut boundary = 0;
+    for (i, m) in history.iter().enumerate().rev() {
+        if m["role"] == "user" && m["content"].is_string() {
+            seen += 1;
+            if seen == keep_turns {
+                boundary = i;
+                break;
+            }
+        }
+    }
+    if seen < keep_turns {
+        return; // whole history is within the keep window
+    }
+    for m in history[..boundary].iter_mut() {
+        // OpenAI shape: {"role": "tool", "content": "..."}
+        if m["role"] == "tool" {
+            if m["content"]
+                .as_str()
+                .is_some_and(|s| s.len() > ELIDED_RESULT.len())
+            {
+                m["content"] = serde_json::json!(ELIDED_RESULT);
+            }
+            continue;
+        }
+        // Anthropic shape: user message whose content is an array of
+        // tool_result blocks.
+        if m["role"] == "user" {
+            if let Some(blocks) = m["content"].as_array_mut() {
+                for b in blocks.iter_mut().filter(|b| b["type"] == "tool_result") {
+                    let long = match &b["content"] {
+                        serde_json::Value::String(s) => s.len() > ELIDED_RESULT.len(),
+                        v => v.to_string().len() > ELIDED_RESULT.len(),
+                    };
+                    if long {
+                        b["content"] = serde_json::json!(ELIDED_RESULT);
+                    }
+                }
+            }
+        }
+    }
+}
+
+/// Full history compaction pass, run once per turn before hitting the API:
+/// age old tool results, apply the turn cap, then drop oldest turns until
+/// the token estimate fits the budget (always keeping the latest turn).
+pub(crate) fn compact_history(history: &mut Vec<serde_json::Value>, cfg: &OrchestratorConfig) {
+    age_tool_results(history, cfg.tool_result_keep_turns);
+    trim_history(history, cfg.max_history_turns);
+    if cfg.max_context_tokens == 0 {
+        return;
+    }
+    while estimate_tokens(history) > cfg.max_context_tokens {
+        let turns = user_turns(history);
+        if turns <= 1 {
+            break; // never drop the turn we're about to answer
+        }
+        trim_history(history, turns - 1);
+    }
+}
+
 /// Trim provider history in place, dropping oldest turns but only cutting at
 /// plain user-text boundaries so tool_use/tool_result pairs stay intact.
 fn trim_history(history: &mut Vec<serde_json::Value>, max_turns: usize) {
@@ -1009,6 +1101,79 @@ mod tests {
         assert_eq!(history.len(), 1);
     }
 
+    #[test]
+    fn aging_stubs_only_old_tool_results() {
+        let big = "x".repeat(500);
+        let mut h = vec![
+            serde_json::json!({"role": "user", "content": "one"}),
+            serde_json::json!({"role": "assistant", "content": [{"type": "tool_use", "id": "a"}]}),
+            serde_json::json!({"role": "user", "content": [
+                {"type": "tool_result", "tool_use_id": "a", "content": big.clone()}]}),
+            serde_json::json!({"role": "assistant", "content": "reply"}),
+            serde_json::json!({"role": "user", "content": "two"}),
+            serde_json::json!({"role": "assistant", "content": [{"type": "tool_use", "id": "b"}]}),
+            serde_json::json!({"role": "user", "content": [
+                {"type": "tool_result", "tool_use_id": "b", "content": big.clone()}]}),
+        ];
+        age_tool_results(&mut h, 1);
+        // Old result stubbed, id preserved
+        assert_eq!(h[2]["content"][0]["content"], ELIDED_RESULT);
+        assert_eq!(h[2]["content"][0]["tool_use_id"], "a");
+        // Result within the keep window untouched
+        assert_eq!(h[6]["content"][0]["content"], big);
+        // keep_turns larger than history: no-op
+        let before = h.clone();
+        age_tool_results(&mut h, 10);
+        assert_eq!(h, before);
+    }
+
+    #[test]
+    fn aging_stubs_openai_tool_messages() {
+        let big = "y".repeat(500);
+        let mut h = vec![
+            serde_json::json!({"role": "user", "content": "one"}),
+            serde_json::json!({"role": "tool", "content": big}),
+            serde_json::json!({"role": "user", "content": "two"}),
+        ];
+        age_tool_results(&mut h, 1);
+        assert_eq!(h[1]["content"], ELIDED_RESULT);
+    }
+
+    #[test]
+    fn budget_trim_drops_oldest_turns_but_keeps_the_last() {
+        let big = "z".repeat(4000); // ~1000 tokens per turn
+        let mut h: Vec<serde_json::Value> = (0..10)
+            .flat_map(|i| {
+                vec![
+                    serde_json::json!({"role": "user", "content": format!("{} {}", i, big)}),
+                    serde_json::json!({"role": "assistant", "content": "ok"}),
+                ]
+            })
+            .collect();
+        let cfg = OrchestratorConfig {
+            max_history_turns: 40,
+            max_context_tokens: 3000,
+            tool_result_keep_turns: 0,
+            ..Default::default()
+        };
+        compact_history(&mut h, &cfg);
+        let turns = user_turns(&h);
+        assert!(turns < 10, "should have dropped turns, kept {}", turns);
+        assert!(turns >= 1, "must keep at least the latest turn");
+        // Latest turn survives
+        assert!(h
+            .iter()
+            .any(|m| m["content"].as_str().is_some_and(|s| s.starts_with("9 "))));
+        // Budget disabled: only the turn cap applies
+        let mut h2 = vec![serde_json::json!({"role": "user", "content": "u".repeat(100000)})];
+        let cfg2 = OrchestratorConfig {
+            max_context_tokens: 0,
+            ..Default::default()
+        };
+        compact_history(&mut h2, &cfg2);
+        assert_eq!(h2.len(), 1);
+    }
+
     #[test]
     fn trim_history_cuts_only_at_plain_user_turns() {
         // 3 user turns, with an assistant tool_use + user tool_result between
diff --git a/src/orchestrator/openai.rs b/src/orchestrator/openai.rs
index c8ed602..373072c 100644
--- a/src/orchestrator/openai.rs
+++ b/src/orchestrator/openai.rs
@@ -21,7 +21,7 @@ pub async fn run_turn(
     let tools = super::openai_tools();
 
     history.push(serde_json::json!({"role": "user", "content": user_text}));
-    super::trim_history(history, cfg.max_history_turns);
+    super::compact_history(history, cfg);
 
     for i in 0..cfg.max_tool_iterations {
         if interrupt.hit() {