Apply agent profile reasoning/temperature frontmatter (GH #828) (#829)

The reasoning and temperature frontmatter keys were parsed into AgentDef
but never read. Wire them into the main loop:

- /agent <name> applies the profile's reasoning via session.effort_override
  (the same mechanism /effort uses, so rebuilds keep it sticky), capturing
  the pre-profile override in ContextFiles.effort_before_agent — the effort
  sibling of route_before_agent. /agent off restores it.
- The profile wins over a live /effort override at activation; a later
  /effort overrides it; /agent off restores the pre-profile value, mirroring
  how the model restore discards a mid-profile /model.
- An unrecognised reasoning value warns and leaves effort untouched; the
  switch proceeds (fail-soft, matching /effort's unknown-level handling).
- temperature is consulted from the active agent layer at agent build time
  (profile > CLI > config), so /agent's rebuild applies it and /agent off's
  rebuild falls back automatically. Same clamp/warn as before.
- Subagent path unchanged (still model + prompt only); docs updated: the
  key table now lists all seven /effort levels and the new semantics.

Verified end-to-end with the wire dump: turn under the profile flips to
model=claude-haiku-4-5 reasoning=false, /agent off returns to
claude-sonnet-5 reasoning=true.

Author: chrismurrph

docs/agents.md

@@ -51,8 +51,8 @@ All frontmatter keys are optional:
 | `model` | A `providers` alias **or** a model name. Resolved to a model string for the current client (see *Model routing* below). Omit to keep the current model. |
 | `deny_tools` | Tools to deny while this profile is active (e.g. `[bash, write, edit, apply_patch]`). |
 | `allow_tools` | The complement: deny every built-in **not** listed. `deny_tools` wins if both are given. |
-| `reasoning` | Reasoning-effort hint (`low` / `medium` / `high`). |
-| `temperature` | Sampling temperature. |
+| `reasoning` | Reasoning effort applied on activation (`off` / `minimal` / `low` / `medium` / `high` / `xhigh` / `max` — the same levels as `/effort`). Wins over any live `/effort` override at activation; a later `/effort` overrides it; `/agent off` restores the pre-profile effort. An unrecognised value warns and leaves the session's effort unchanged. |
+| `temperature` | Sampling temperature while the profile is active (clamped to `0.0..=2.0`). Wins over `--temperature` and the config default; `/agent off` falls back to those. |
 | `description` | One-line summary shown in `/agents`. |
 | `subagent_tools` | Opt this profile's `task(agent=…)` subagent into tools: `readonly` (read-only tool universe), `readwrite` (readonly + write/edit/bash — can edit the repo), or `toolless` (the default one-shot). See *Tooled subagents* below. |
 | `subagent_max_turns` | Cap the tooled subagent's loop (default `25`). |
@@ -155,7 +155,8 @@ Profiles are resolved into subagent routes once at startup. By default
 subagents are **tool-less** (a one-shot query — a profile's
 `deny_tools`/`allow_tools` doesn't apply, since the subagent has no tools),
 and the profile's `reasoning`/`temperature` aren't applied on the subagent
-path — only the model and system prompt are. Routing `/plan` phases to named
+path — only the model and system prompt are (the MAIN loop applies both when
+the profile is activated with `/agent <name>`; see the key table above). Routing `/plan` phases to named
 profiles, and cross-provider client switching, remain follow-ups.
 
 ### Tooled subagents (opt-in)

src/agent/builder/agent_inner.rs

@@ -316,9 +316,17 @@ pub async fn build_agent_inner<M: CompletionModel + 'static>(
     let max_turns = cli.resolve_max_agent_turns(cfg);
     builder = builder.default_max_turns(max_turns);
 
-    // Temperature: CLI > config > unset. Previously only `cli.temperature`
-    // was checked, so users couldn't set a default in config.json.
-    if let Some(temp) = cli.resolve_temperature(cfg) {
+    // Temperature: active agent profile > CLI > config > unset. Previously
+    // only `cli.temperature` was checked, so users couldn't set a default in
+    // config.json. The profile tier (GH #828) reads the `/agent` layer's
+    // `temperature` frontmatter — parsed since the key was introduced but
+    // never consumed. Consulting the layer HERE (rather than a runtime
+    // setter, which `AnyAgent` has none of for temperature) means `/agent
+    // <name>`'s rebuild picks it up and `/agent off`'s rebuild, with the
+    // layer cleared, falls straight back to CLI/config — no capture/restore
+    // needed. A profile omitting the key changes nothing.
+    let profile_temp = context.agent_layer.as_ref().and_then(|d| d.temperature);
+    if let Some(temp) = profile_temp.or_else(|| cli.resolve_temperature(cfg)) {
         let clamped = temp.clamp(0.0, 2.0);
         if (clamped - temp).abs() > f64::EPSILON {
             // Warn ONCE per process if the user's value was clamped

src/agent/builder/reminder_tests.rs

@@ -539,6 +539,7 @@ async fn build_agent_inner_emits_assembled_preamble() {
         prompt_layer: None,
         agent_layer: None,
         route_before_agent: None,
+        effort_before_agent: None,
     };
     // Real openai client/model — never called (no network until
     // first request). The builder only inspects type bounds and
@@ -687,6 +688,7 @@ async fn preamble_lists_global_tier_skills() {
         prompt_layer: None,
         agent_layer: None,
         route_before_agent: None,
+        effort_before_agent: None,
     };
     let client = openai::Client::new("test-key").expect("openai client builds");
     let model = client.completion_model("gpt-4o");
@@ -768,6 +770,7 @@ async fn no_skills_suppresses_the_preamble_catalog() {
         prompt_layer: None,
         agent_layer: None,
         route_before_agent: None,
+        effort_before_agent: None,
     };
     let client = openai::Client::new("test-key").expect("openai client builds");
     let model = client.completion_model("gpt-4o");
@@ -816,6 +819,7 @@ async fn steering_fragment_tracks_active_model_not_cli() {
         prompt_layer: None,
         agent_layer: None,
         route_before_agent: None,
+        effort_before_agent: None,
     };
     let client = openai::Client::new("test-key").expect("openai client builds");
 

src/context/mod.rs

@@ -60,6 +60,14 @@ pub struct ContextFiles {
     /// leave the pre-agent model pointed at the profile's provider
     /// (dirge-fhr5). `None` when no agent is active.
     pub route_before_agent: Option<crate::provider::ModelRoute>,
+    /// The `session.effort_override` in force when an agent profile first
+    /// applied its `reasoning` frontmatter (GH #828), so `/agent off` can
+    /// restore it — the effort sibling of `route_before_agent`. Outer
+    /// `None` = nothing captured (no active profile has applied
+    /// `reasoning`); `Some(None)` = there was no override before the
+    /// profile (restore falls back to the provider config default on
+    /// rebuild).
+    pub effort_before_agent: Option<Option<crate::agent::agent_loop::types::ThinkingLevel>>,
 }
 
 /// The `/prompt`-selected layer: a named mode with a body and its own
@@ -191,6 +199,7 @@ pub fn load(no_context_files: bool) -> ContextFiles {
         prompt_layer: None,
         agent_layer: None,
         route_before_agent: None,
+        effort_before_agent: None,
     }
 }
 
@@ -306,6 +315,7 @@ mod composition_tests {
             prompt_layer: None,
             agent_layer: None,
             route_before_agent: None,
+            effort_before_agent: None,
         }
     }
 

src/provider/mod_tests.rs

@@ -1702,6 +1702,7 @@ async fn cerebras_identity_survives_client_model_and_agent_construction() {
         prompt_layer: None,
         agent_layer: None,
         route_before_agent: None,
+        effort_before_agent: None,
     };
     let agent = build_agent(
         model,
@@ -1768,6 +1769,7 @@ async fn provider_effort_config_seeds_agent_reasoning() {
         prompt_layer: None,
         agent_layer: None,
         route_before_agent: None,
+        effort_before_agent: None,
     };
     let agent = build_agent(
         model,

src/ui/slash/cmd/agent/clear.rs

@@ -33,6 +33,20 @@ pub(crate) async fn cmd_agent_clear(ctx: &mut SlashCtx<'_>) -> anyhow::Result<()
         ));
     }
 
+    // Restore the pre-profile effort override captured when a profile's
+    // `reasoning` frontmatter was applied (GH #828) — the effort sibling of
+    // the route restore above, and deliberately independent of it: a refused
+    // model restore must not leave the profile's reasoning behind. Restoring
+    // the pre-profile value also discards any `/effort` issued WHILE the
+    // profile was active, exactly as the route restore discards a mid-profile
+    // `/model`. Done before `rebuild_agent` so the rebuild installs the
+    // restored override (or, for `Some(None)`, re-seeds the provider config
+    // default) on the live agent.
+    restore_profile_reasoning(
+        &mut ctx.session.effort_override,
+        &mut ctx.context.effort_before_agent,
+    );
+
     rebuild_agent(ctx).await;
 
     if let Some(err) = restore_error {
@@ -47,3 +61,17 @@ pub(crate) async fn cmd_agent_clear(ctx: &mut SlashCtx<'_>) -> anyhow::Result<()
     ctx.renderer.write_line(&msg, c_agent())?;
     Ok(())
 }
+
+/// Put `session.effort_override` back to the value captured when an agent
+/// profile first applied its `reasoning` frontmatter (GH #828). A no-op
+/// when nothing was captured (no active profile ever set `reasoning`), so a
+/// profile without the key leaves the session's effort untouched in both
+/// directions.
+pub(crate) fn restore_profile_reasoning(
+    effort_override: &mut Option<crate::agent::agent_loop::types::ThinkingLevel>,
+    effort_before_agent: &mut Option<Option<crate::agent::agent_loop::types::ThinkingLevel>>,
+) {
+    if let Some(prior) = effort_before_agent.take() {
+        *effort_override = prior;
+    }
+}

src/ui/slash/cmd/agent/switch.rs

@@ -58,6 +58,33 @@ pub(crate) async fn cmd_agent_switch(ctx: &mut SlashCtx<'_>, arg: &str) -> anyho
         }
     }
 
+    // Apply the profile's `reasoning` frontmatter (GH #828) — parsed since
+    // the key was introduced but never consumed. It layers exactly like the
+    // model: the profile's level wins at activation (over any live `/effort`
+    // override), a later `/effort` overrides it as it would any current
+    // level, and `/agent off` restores what was captured here. Applied even
+    // when the model route was refused above — the profile stays active in
+    // that case, so its reasoning does too. Written to
+    // `session.effort_override` (not `set_reasoning` directly) so the
+    // `rebuild_agent` below installs it on the live agent and every later
+    // rebuild keeps it sticky, the same way `/effort` survives `/model`.
+    let mut applied_effort = None;
+    if let Some(raw) = def.reasoning.as_deref() {
+        match apply_profile_reasoning(
+            raw,
+            &mut ctx.session.effort_override,
+            &mut ctx.context.effort_before_agent,
+        ) {
+            Ok(level) => applied_effort = Some(level),
+            // Fail soft: warn and leave the session's effort alone, the same
+            // way `/effort` treats an unknown level. Never abort the switch —
+            // the rest of the profile is still valid.
+            Err(msg) => ctx
+                .renderer
+                .write_line(&format!("agent '{}': {msg}", def.name), c_error())?,
+        }
+    }
+
     rebuild_agent(ctx).await;
 
     let mut summary = format!("active agent: {}", def.name);
@@ -67,6 +94,169 @@ pub(crate) async fn cmd_agent_switch(ctx: &mut SlashCtx<'_>, arg: &str) -> anyho
     if let Some(alias) = &switched_to {
         summary.push_str(&format!("  ·  {alias}"));
     }
+    if let Some(level) = applied_effort {
+        summary.push_str(&format!("  · effort {}", level.effort_label()));
+    }
     ctx.renderer.write_line(&summary, c_agent())?;
     Ok(())
 }
+
+/// Apply an agent profile's `reasoning` frontmatter value to the session's
+/// effort override (GH #828), capturing the pre-profile override on the
+/// FIRST profile application so `/agent off` can restore it. The capture
+/// guard is `effort_before_agent`, not the agent layer: profile A without a
+/// `reasoning` key followed by profile B with one must capture at B, and
+/// A-with-B-with must keep A's capture (the pre-agent value) — mirroring
+/// how `route_before_agent` holds the pre-agent route across profile hops.
+///
+/// Returns the level applied, or `Err` with a warning message (worded like
+/// `/effort`'s unknown-level error) when `raw` is not a recognised level —
+/// in which case NOTHING is touched: no capture, no override change.
+pub(crate) fn apply_profile_reasoning(
+    raw: &str,
+    effort_override: &mut Option<crate::agent::agent_loop::types::ThinkingLevel>,
+    effort_before_agent: &mut Option<Option<crate::agent::agent_loop::types::ThinkingLevel>>,
+) -> Result<crate::agent::agent_loop::types::ThinkingLevel, String> {
+    use crate::agent::agent_loop::types::ThinkingLevel;
+    let Some(level) = ThinkingLevel::from_effort_str(raw) else {
+        return Err(format!(
+            "unknown reasoning `{}` — expected off/minimal/low/medium/high/xhigh/max; \
+             leaving effort unchanged",
+            raw.trim(),
+        ));
+    };
+    if effort_before_agent.is_none() {
+        *effort_before_agent = Some(*effort_override);
+    }
+    *effort_override = Some(level);
+    Ok(level)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::super::clear::restore_profile_reasoning;
+    use super::apply_profile_reasoning;
+    use crate::agent::agent_loop::types::ThinkingLevel;
+
+    // GH #828: a profile's `reasoning` is applied on activation and the
+    // pre-profile state (no override) is captured for `/agent off`.
+    #[test]
+    fn profile_reasoning_is_applied_and_prior_state_captured() {
+        let mut over = None;
+        let mut before = None;
+        let applied = apply_profile_reasoning("low", &mut over, &mut before);
+        assert_eq!(applied, Ok(ThinkingLevel::Low));
+        assert_eq!(over, Some(ThinkingLevel::Low));
+        assert_eq!(before, Some(None), "must capture 'no prior override'");
+    }
+
+    // Precedence at activation: the profile wins over a live `/effort`
+    // override, the same way its model wins over a `/model` choice — and
+    // the displaced override is what `/agent off` will restore.
+    #[test]
+    fn profile_reasoning_wins_over_live_effort_override_at_activation() {
+        let mut over = Some(ThinkingLevel::Max);
+        let mut before = None;
+        let applied = apply_profile_reasoning("low", &mut over, &mut before);
+        assert_eq!(applied, Ok(ThinkingLevel::Low));
+        assert_eq!(over, Some(ThinkingLevel::Low));
+        assert_eq!(before, Some(Some(ThinkingLevel::Max)));
+    }
+
+    // `/agent off` restores the pre-profile override.
+    #[test]
+    fn restore_returns_the_pre_profile_override() {
+        let mut over = Some(ThinkingLevel::High);
+        let mut before = None;
+        apply_profile_reasoning("off", &mut over, &mut before).unwrap();
+        restore_profile_reasoning(&mut over, &mut before);
+        assert_eq!(over, Some(ThinkingLevel::High));
+        assert_eq!(before, None, "capture must be consumed");
+    }
+
+    // `/agent off` after a profile applied over NO prior override restores
+    // "no override" (the rebuild then re-seeds the provider config default).
+    #[test]
+    fn restore_returns_no_override_when_there_was_none_before() {
+        let mut over = None;
+        let mut before = None;
+        apply_profile_reasoning("medium", &mut over, &mut before).unwrap();
+        restore_profile_reasoning(&mut over, &mut before);
+        assert_eq!(over, None);
+        assert_eq!(before, None);
+    }
+
+    // A `/effort` issued WHILE the profile is active is discarded by
+    // `/agent off` in favour of the pre-profile value — mirroring how the
+    // route restore discards a mid-profile `/model`.
+    #[test]
+    fn restore_discards_a_mid_profile_effort_change() {
+        let mut over = Some(ThinkingLevel::Medium);
+        let mut before = None;
+        apply_profile_reasoning("low", &mut over, &mut before).unwrap();
+        over = Some(ThinkingLevel::Xhigh); // user ran `/effort xhigh` mid-profile
+        restore_profile_reasoning(&mut over, &mut before);
+        assert_eq!(over, Some(ThinkingLevel::Medium));
+    }
+
+    // A profile that omits `reasoning` never calls apply — so on `/agent
+    // off` there is no capture, and restore must change NOTHING (a
+    // key-less profile leaves effort alone in both directions).
+    #[test]
+    fn restore_without_a_capture_is_a_no_op() {
+        let mut over = Some(ThinkingLevel::Max);
+        let mut before = None;
+        restore_profile_reasoning(&mut over, &mut before);
+        assert_eq!(over, Some(ThinkingLevel::Max));
+    }
+
+    // An invalid value fails soft: warn (the Err), touch nothing, never
+    // abort the switch.
+    #[test]
+    fn invalid_reasoning_value_changes_nothing() {
+        let mut over = Some(ThinkingLevel::High);
+        let mut before = None;
+        let res = apply_profile_reasoning("turbo", &mut over, &mut before);
+        assert!(res.is_err());
+        assert!(res.unwrap_err().contains("unknown reasoning `turbo`"));
+        assert_eq!(over, Some(ThinkingLevel::High), "override untouched");
+        assert_eq!(before, None, "no capture on failure");
+    }
+
+    // Hopping profile A -> profile B keeps A's capture: the value `/agent
+    // off` restores is the PRE-AGENT one, exactly as `route_before_agent`
+    // holds the pre-agent route across profile hops.
+    #[test]
+    fn profile_hop_keeps_the_pre_agent_capture() {
+        let mut over = Some(ThinkingLevel::Minimal);
+        let mut before = None;
+        apply_profile_reasoning("high", &mut over, &mut before).unwrap();
+        apply_profile_reasoning("max", &mut over, &mut before).unwrap();
+        assert_eq!(over, Some(ThinkingLevel::Max));
+        assert_eq!(before, Some(Some(ThinkingLevel::Minimal)));
+        restore_profile_reasoning(&mut over, &mut before);
+        assert_eq!(over, Some(ThinkingLevel::Minimal));
+    }
+
+    // All seven `/effort` levels are accepted — the profile key must never
+    // diverge from `/effort`'s vocabulary (they share the parser).
+    #[test]
+    fn all_seven_effort_levels_parse() {
+        for (raw, want) in [
+            ("off", ThinkingLevel::Off),
+            ("minimal", ThinkingLevel::Minimal),
+            ("low", ThinkingLevel::Low),
+            ("medium", ThinkingLevel::Medium),
+            ("high", ThinkingLevel::High),
+            ("xhigh", ThinkingLevel::Xhigh),
+            ("max", ThinkingLevel::Max),
+        ] {
+            let mut over = None;
+            let mut before = None;
+            assert_eq!(
+                apply_profile_reasoning(raw, &mut over, &mut before),
+                Ok(want)
+            );
+        }
+    }
+}