lean_ctx/core/

memory_policy.rs

use serde::{Deserialize, Serialize};

#[derive(Debug, Clone, Serialize, Deserialize, Default)]
#[serde(default)]
pub struct MemoryPolicy {
    pub knowledge: KnowledgePolicy,
    pub episodic: EpisodicPolicy,
    pub procedural: ProceduralPolicy,
    pub lifecycle: LifecyclePolicy,
    pub embeddings: EmbeddingsPolicy,
    pub gotcha: GotchaPolicy,
    pub admission: AdmissionPolicy,
    pub compaction: CompactionPolicy,
}

impl MemoryPolicy {
    pub fn apply_env_overrides(&mut self) {
        self.knowledge.apply_env_overrides();
        self.lifecycle.apply_env_overrides();
        self.embeddings.apply_env_overrides();
        self.gotcha.apply_env_overrides();
        self.admission.apply_env_overrides();
    }

    pub fn apply_overrides(&mut self, o: &MemoryPolicyOverrides) {
        self.knowledge.apply_overrides(&o.knowledge);
        self.lifecycle.apply_overrides(&o.lifecycle);
    }

    pub fn validate(&self) -> Result<(), String> {
        self.knowledge.validate()?;
        self.lifecycle.validate()?;
        self.embeddings.validate()?;
        self.gotcha.validate()?;
        self.admission.validate()?;
        Ok(())
    }
}

#[derive(Debug, Clone, Serialize, Deserialize, Default)]
#[serde(default)]
pub struct MemoryPolicyOverrides {
    pub knowledge: KnowledgePolicyOverrides,
    pub lifecycle: LifecyclePolicyOverrides,
}

#[derive(Debug, Clone, Serialize, Deserialize, Default)]
#[serde(default)]
pub struct KnowledgePolicyOverrides {
    // A profile's `max_facts` (removed fact cap) is an unknown key here and
    // skipped by serde; see `KnowledgePolicy::max_facts`.
    pub max_patterns: Option<usize>,
    pub max_history: Option<usize>,
    pub contradiction_threshold: Option<f32>,
    pub recall_facts_limit: Option<usize>,
    pub rooms_limit: Option<usize>,
    pub timeline_limit: Option<usize>,
    pub relations_limit: Option<usize>,
}

#[derive(Debug, Clone, Serialize, Deserialize, Default)]
#[serde(default)]
pub struct LifecyclePolicyOverrides {
    pub decay_rate: Option<f32>,
    pub low_confidence_threshold: Option<f32>,
    pub stale_days: Option<i64>,
    pub similarity_threshold: Option<f32>,
    pub forgetting_model: Option<String>,
    pub base_stability_days: Option<f32>,
    pub archetype_aware_decay: Option<bool>,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(default)]
pub struct KnowledgePolicy {
    /// Deprecated and ignored (3.12.1): knowledge has no fact limit (owner
    /// decision 2026-10-24). Kept only so an existing `max_facts` in a
    /// config.toml still loads and round-trips; nothing reads it. Facts leave
    /// the active store by quality alone (decay, near-duplicate merge,
    /// low-confidence/stale archival), never by count.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub max_facts: Option<usize>,
    pub max_patterns: usize,
    pub max_history: usize,
    pub contradiction_threshold: f32,
    /// Maximum number of facts returned by recall operations.
    pub recall_facts_limit: usize,
    /// Maximum number of rooms returned by `ctx_knowledge action=rooms`.
    pub rooms_limit: usize,
    /// Maximum number of timeline entries returned by `ctx_knowledge action=timeline`.
    pub timeline_limit: usize,
    /// Maximum number of relations/edges returned by relations queries/diagrams.
    pub relations_limit: usize,
}

impl Default for KnowledgePolicy {
    fn default() -> Self {
        Self {
            max_facts: None,
            max_patterns: 50,
            max_history: 100,
            contradiction_threshold: 0.5,
            recall_facts_limit: crate::core::budgets::KNOWLEDGE_RECALL_FACTS_LIMIT,
            rooms_limit: crate::core::budgets::KNOWLEDGE_ROOMS_LIMIT,
            timeline_limit: crate::core::budgets::KNOWLEDGE_TIMELINE_LIMIT,
            relations_limit: 40,
        }
    }
}

impl KnowledgePolicy {
    fn apply_env_overrides(&mut self) {
        // `LEAN_CTX_KNOWLEDGE_MAX_FACTS` is ignored: knowledge has no fact limit.
        if let Ok(v) = std::env::var("LEAN_CTX_KNOWLEDGE_MAX_PATTERNS")
            && let Ok(n) = v.parse()
        {
            self.max_patterns = n;
        }
        if let Ok(v) = std::env::var("LEAN_CTX_KNOWLEDGE_MAX_HISTORY")
            && let Ok(n) = v.parse()
        {
            self.max_history = n;
        }
        if let Ok(v) = std::env::var("LEAN_CTX_KNOWLEDGE_CONTRADICTION_THRESHOLD")
            && let Ok(n) = v.parse()
        {
            self.contradiction_threshold = n;
        }
        if let Ok(v) = std::env::var("LEAN_CTX_KNOWLEDGE_RECALL_FACTS_LIMIT")
            && let Ok(n) = v.parse()
        {
            self.recall_facts_limit = n;
        }
        if let Ok(v) = std::env::var("LEAN_CTX_KNOWLEDGE_ROOMS_LIMIT")
            && let Ok(n) = v.parse()
        {
            self.rooms_limit = n;
        }
        if let Ok(v) = std::env::var("LEAN_CTX_KNOWLEDGE_TIMELINE_LIMIT")
            && let Ok(n) = v.parse()
        {
            self.timeline_limit = n;
        }
        if let Ok(v) = std::env::var("LEAN_CTX_KNOWLEDGE_RELATIONS_LIMIT")
            && let Ok(n) = v.parse()
        {
            self.relations_limit = n;
        }
    }

    fn validate(&self) -> Result<(), String> {
        // `max_facts` is ignored, so any value (0 included) is accepted.
        if self.max_patterns == 0 {
            return Err("memory.knowledge.max_patterns must be > 0".to_string());
        }
        if self.max_history == 0 {
            return Err("memory.knowledge.max_history must be > 0".to_string());
        }
        if !(0.0..=1.0).contains(&self.contradiction_threshold) {
            return Err(
                "memory.knowledge.contradiction_threshold must be in [0.0, 1.0]".to_string(),
            );
        }
        if self.recall_facts_limit == 0 {
            return Err("memory.knowledge.recall_facts_limit must be > 0".to_string());
        }
        if self.rooms_limit == 0 {
            return Err("memory.knowledge.rooms_limit must be > 0".to_string());
        }
        if self.timeline_limit == 0 {
            return Err("memory.knowledge.timeline_limit must be > 0".to_string());
        }
        if self.relations_limit == 0 {
            return Err("memory.knowledge.relations_limit must be > 0".to_string());
        }
        Ok(())
    }

    fn apply_overrides(&mut self, o: &KnowledgePolicyOverrides) {
        if let Some(v) = o.max_patterns {
            self.max_patterns = v;
        }
        if let Some(v) = o.max_history {
            self.max_history = v;
        }
        if let Some(v) = o.contradiction_threshold {
            self.contradiction_threshold = v;
        }
        if let Some(v) = o.recall_facts_limit {
            self.recall_facts_limit = v;
        }
        if let Some(v) = o.rooms_limit {
            self.rooms_limit = v;
        }
        if let Some(v) = o.timeline_limit {
            self.timeline_limit = v;
        }
        if let Some(v) = o.relations_limit {
            self.relations_limit = v;
        }
    }
}

/// `[memory.episodic]`: no effect. The episode memory is retired
/// (DEPRECATIONS.toml `config-memory-episodic-procedural`); the section stays
/// accepted, unvalidated, so existing configs keep loading. Its
/// `LEAN_CTX_EPISODIC_*` environment variables are ignored.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(default)]
pub struct EpisodicPolicy {
    pub max_episodes: usize,
    pub max_actions_per_episode: usize,
    pub summary_max_chars: usize,
}

impl Default for EpisodicPolicy {
    fn default() -> Self {
        Self {
            max_episodes: 500,
            max_actions_per_episode: 50,
            summary_max_chars: 200,
        }
    }
}

/// `[memory.procedural]`: no effect. The procedure memory is retired
/// (DEPRECATIONS.toml `config-memory-episodic-procedural`); the section stays
/// accepted, unvalidated, so existing configs keep loading. Its
/// `LEAN_CTX_PROCEDURAL_*` environment variables are ignored.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(default)]
pub struct ProceduralPolicy {
    pub min_repetitions: usize,
    pub min_sequence_len: usize,
    pub max_procedures: usize,
    pub max_window_size: usize,
}

impl Default for ProceduralPolicy {
    fn default() -> Self {
        Self {
            min_repetitions: 3,
            min_sequence_len: 2,
            max_procedures: 100,
            max_window_size: 10,
        }
    }
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(default)]
pub struct LifecyclePolicy {
    pub decay_rate: f32,
    pub low_confidence_threshold: f32,
    pub stale_days: i64,
    pub similarity_threshold: f32,
    /// Forgetting curve (#1): `ebbinghaus` (default) or `linear` (legacy).
    pub forgetting_model: String,
    /// Characteristic memory stability in days for the Ebbinghaus curve.
    pub base_stability_days: f32,
    /// Scale Ebbinghaus stability by fact archetype so structural evidence decays
    /// slower than inference. Default false keeps the baseline tuning unchanged.
    pub archetype_aware_decay: bool,
    /// Archive single-confirmation facts untouched for this many days that were
    /// never retrieved — dead weight regardless of confidence (#962). Defaults to
    /// a conservative 90 days (#972): genuinely cold facts are archived (and
    /// rehydrate on recall), so a store self-curates instead of only churning at
    /// its cap. Set `None`/`off` to disable.
    pub prune_unretrieved_after_days: Option<i64>,
    /// Proactive headroom on a capacity reclaim (#995): when a store reaches its
    /// cap, settle it at `1 - reclaim_headroom_pct` (e.g. `0.25` → 75%) instead
    /// of churning right at the cap. Lossless — the reclaimed tail is archived
    /// and restorable.
    pub reclaim_headroom_pct: f32,
    /// Master switch for the proactive reclaim (#995). `false` is the documented
    /// escape hatch: trim only the overflow, no headroom. Eviction stays lossless
    /// either way.
    pub reclaim_enabled: bool,
}

impl Default for LifecyclePolicy {
    fn default() -> Self {
        Self {
            decay_rate: 0.01,
            low_confidence_threshold: 0.3,
            stale_days: 30,
            similarity_threshold: 0.85,
            forgetting_model: "ebbinghaus".to_string(),
            base_stability_days: crate::core::memory_lifecycle::DEFAULT_BASE_STABILITY_DAYS,
            archetype_aware_decay: false,
            prune_unretrieved_after_days: Some(90),
            reclaim_headroom_pct: crate::core::memory_lifecycle::DEFAULT_RECLAIM_HEADROOM_PCT,
            reclaim_enabled: true,
        }
    }
}

impl LifecyclePolicy {
    fn apply_env_overrides(&mut self) {
        if let Ok(v) = std::env::var("LEAN_CTX_LIFECYCLE_DECAY_RATE")
            && let Ok(n) = v.parse()
        {
            self.decay_rate = n;
        }
        if let Ok(v) = std::env::var("LEAN_CTX_LIFECYCLE_LOW_CONFIDENCE_THRESHOLD")
            && let Ok(n) = v.parse()
        {
            self.low_confidence_threshold = n;
        }
        if let Ok(v) = std::env::var("LEAN_CTX_LIFECYCLE_STALE_DAYS")
            && let Ok(n) = v.parse()
        {
            self.stale_days = n;
        }
        if let Ok(v) = std::env::var("LEAN_CTX_LIFECYCLE_SIMILARITY_THRESHOLD")
            && let Ok(n) = v.parse()
        {
            self.similarity_threshold = n;
        }
        if let Ok(v) = std::env::var("LEAN_CTX_LIFECYCLE_FORGETTING") {
            self.forgetting_model = v;
        }
        if let Ok(v) = std::env::var("LEAN_CTX_LIFECYCLE_BASE_STABILITY_DAYS")
            && let Ok(n) = v.parse()
        {
            self.base_stability_days = n;
        }
        if let Ok(v) = std::env::var("LEAN_CTX_LIFECYCLE_ARCHETYPE_AWARE") {
            self.archetype_aware_decay = v == "1" || v.eq_ignore_ascii_case("true");
        }
        if let Ok(v) = std::env::var("LEAN_CTX_LIFECYCLE_PRUNE_UNRETRIEVED_DAYS") {
            self.prune_unretrieved_after_days = match v.trim().to_lowercase().as_str() {
                "" | "off" | "none" | "0" => None,
                s => s.parse::<i64>().ok().filter(|&n| n > 0),
            };
        }
        if let Ok(v) = std::env::var("LEAN_CTX_LIFECYCLE_RECLAIM_HEADROOM_PCT")
            && let Ok(n) = v.parse()
        {
            self.reclaim_headroom_pct = n;
        }
        if let Ok(v) = std::env::var("LEAN_CTX_LIFECYCLE_RECLAIM_ENABLED") {
            self.reclaim_enabled = !(v == "0" || v.eq_ignore_ascii_case("false"));
        }
    }

    fn validate(&self) -> Result<(), String> {
        if !(0.0..=1.0).contains(&self.decay_rate) {
            return Err("memory.lifecycle.decay_rate must be in [0.0, 1.0]".to_string());
        }
        if !(0.0..=1.0).contains(&self.low_confidence_threshold) {
            return Err(
                "memory.lifecycle.low_confidence_threshold must be in [0.0, 1.0]".to_string(),
            );
        }
        if self.stale_days < 0 {
            return Err("memory.lifecycle.stale_days must be >= 0".to_string());
        }
        if !(0.0..=1.0).contains(&self.similarity_threshold) {
            return Err("memory.lifecycle.similarity_threshold must be in [0.0, 1.0]".to_string());
        }
        if self.base_stability_days <= 0.0 {
            return Err("memory.lifecycle.base_stability_days must be > 0".to_string());
        }
        if !(0.0..=0.95).contains(&self.reclaim_headroom_pct) {
            return Err("memory.lifecycle.reclaim_headroom_pct must be in [0.0, 0.95]".to_string());
        }
        Ok(())
    }

    fn apply_overrides(&mut self, o: &LifecyclePolicyOverrides) {
        if let Some(v) = o.decay_rate {
            self.decay_rate = v;
        }
        if let Some(v) = o.low_confidence_threshold {
            self.low_confidence_threshold = v;
        }
        if let Some(v) = o.stale_days {
            self.stale_days = v;
        }
        if let Some(v) = o.similarity_threshold {
            self.similarity_threshold = v;
        }
        if let Some(ref v) = o.forgetting_model {
            self.forgetting_model.clone_from(v);
        }
        if let Some(v) = o.base_stability_days {
            self.base_stability_days = v;
        }
        if let Some(v) = o.archetype_aware_decay {
            self.archetype_aware_decay = v;
        }
    }
}

#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(default)]
pub struct EmbeddingsPolicy {
    pub max_facts: usize,
}

impl Default for EmbeddingsPolicy {
    fn default() -> Self {
        Self { max_facts: 2000 }
    }
}

impl EmbeddingsPolicy {
    fn apply_env_overrides(&mut self) {
        if let Ok(v) = std::env::var("LEAN_CTX_KNOWLEDGE_EMBEDDINGS_MAX_FACTS")
            && let Ok(n) = v.parse()
        {
            self.max_facts = n;
        }
    }

    fn validate(&self) -> Result<(), String> {
        if self.max_facts == 0 {
            return Err("memory.embeddings.max_facts must be > 0".to_string());
        }
        Ok(())
    }
}

/// Gotcha store bounds (`[memory.gotcha]`).
///
/// Decay follows each gotcha's provenance (promoted, agent-reported,
/// correlated, auto-detected), so the former `default_decay_rate`,
/// `category_decay_overrides`, `retrieval_budget_per_room` and
/// `auto_expire_days` keys were never applied; they are retired
/// (`config::retired`) and ignored when an older config loads.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(default)]
pub struct GotchaPolicy {
    /// Most gotchas kept per project; the lowest-confidence ones are dropped
    /// first. Env: `LEAN_CTX_GOTCHA_MAX_PER_PROJECT`.
    pub max_gotchas_per_project: usize,
}

impl Default for GotchaPolicy {
    fn default() -> Self {
        Self {
            max_gotchas_per_project: 100,
        }
    }
}

impl GotchaPolicy {
    fn apply_env_overrides(&mut self) {
        if let Ok(v) = std::env::var("LEAN_CTX_GOTCHA_MAX_PER_PROJECT")
            && let Ok(n) = v.parse()
        {
            self.max_gotchas_per_project = n;
        }
    }

    fn validate(&self) -> Result<(), String> {
        if self.max_gotchas_per_project == 0 {
            return Err("memory.gotcha.max_gotchas_per_project must be > 0".to_string());
        }
        Ok(())
    }
}

/// Write-time admission control for the knowledge store (#970). The cap +
/// importance-eviction is a backstop *after* the fact is written; admission is
/// the boundary *before* it, so a capped store fills with signal, not noise.
/// Applied only to direct `ctx_knowledge remember` (the agent-facing path);
/// internal restorers (archive rehydrate, cognition auto-promotion) bypass it.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(default)]
pub struct AdmissionPolicy {
    /// Master switch for write-time admission. When off, every `remember`
    /// inserts as before (legacy behavior).
    pub enabled: bool,
    /// A new fact whose value is at least this similar (word-Jaccard, 0.0–1.0) to
    /// an existing *current* fact in the **same category** under a different key
    /// is merged into it (a confirmation bump) instead of inserted as a new row.
    /// High by default so only genuine near-duplicates collapse; `0.0` disables
    /// auto-merge.
    pub auto_merge_similarity: f32,
    /// Facts whose content salience (`crate::core::memory_salience::text_salience`)
    /// is below this floor are not admitted as normal facts. `0` (default)
    /// disables the floor — the lossless choice; raise it to curate a noisy store.
    pub min_salience: u32,
}

impl Default for AdmissionPolicy {
    fn default() -> Self {
        Self {
            enabled: true,
            auto_merge_similarity: 0.9,
            min_salience: 0,
        }
    }
}

impl AdmissionPolicy {
    fn apply_env_overrides(&mut self) {
        if let Ok(v) = std::env::var("LEAN_CTX_ADMISSION_ENABLED") {
            self.enabled = !(v == "0" || v.eq_ignore_ascii_case("false"));
        }
        if let Ok(v) = std::env::var("LEAN_CTX_ADMISSION_MERGE_SIMILARITY")
            && let Ok(n) = v.parse()
        {
            self.auto_merge_similarity = n;
        }
        if let Ok(v) = std::env::var("LEAN_CTX_ADMISSION_MIN_SALIENCE")
            && let Ok(n) = v.parse()
        {
            self.min_salience = n;
        }
    }

    fn validate(&self) -> Result<(), String> {
        if !(0.0..=1.0).contains(&self.auto_merge_similarity) {
            return Err("memory.admission.auto_merge_similarity must be in [0.0, 1.0]".to_string());
        }
        Ok(())
    }
}

/// `[memory.compaction]`: no effect. Cluster compaction (#971) ran only in the
/// retired cognition loop (DEPRECATIONS.toml `config-memory-compaction`); the
/// section stays accepted, unvalidated, so existing configs keep loading.
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(default)]
pub struct CompactionPolicy {
    pub enabled: bool,
    pub min_cluster: usize,
    pub similarity: f32,
    pub max_confidence: f32,
    pub max_confirmations: u32,
}

impl Default for CompactionPolicy {
    fn default() -> Self {
        Self {
            enabled: true,
            min_cluster: 4,
            similarity: 0.5,
            max_confidence: 0.5,
            max_confirmations: 1,
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    fn restore_env(key: &str, prev: Option<String>) {
        match prev {
            Some(v) => crate::test_env::set_var(key, v),
            None => crate::test_env::remove_var(key),
        }
    }

    #[test]
    fn default_policy_is_valid() {
        let p = MemoryPolicy::default();
        p.validate().expect("default policy must be valid");
    }

    #[test]
    fn memory_discipline_defaults_are_premium() {
        // #970/#971/#972: self-curation is on by default, but lossless.
        let p = MemoryPolicy::default();
        assert!(p.admission.enabled, "admission on by default");
        assert_eq!(p.admission.min_salience, 0, "salience floor off (lossless)");
        assert_eq!(
            p.lifecycle.prune_unretrieved_after_days,
            Some(90),
            "conservative recoverable prune default"
        );
    }

    #[test]
    fn admission_env_overrides_apply() {
        let _lock = crate::core::data_dir::test_env_lock();

        let prev = [
            (
                "LEAN_CTX_ADMISSION_ENABLED",
                std::env::var("LEAN_CTX_ADMISSION_ENABLED").ok(),
            ),
            (
                "LEAN_CTX_ADMISSION_MIN_SALIENCE",
                std::env::var("LEAN_CTX_ADMISSION_MIN_SALIENCE").ok(),
            ),
        ];
        crate::test_env::set_var("LEAN_CTX_ADMISSION_ENABLED", "0");
        crate::test_env::set_var("LEAN_CTX_ADMISSION_MIN_SALIENCE", "42");

        let mut p = MemoryPolicy::default();
        p.apply_env_overrides();

        assert!(!p.admission.enabled);
        assert_eq!(p.admission.min_salience, 42);

        for (key, val) in prev {
            restore_env(key, val);
        }
    }

    #[test]
    fn validate_rejects_invalid_admission() {
        let mut p = MemoryPolicy::default();
        p.admission.auto_merge_similarity = 1.5;
        assert!(p.validate().is_err());
    }

    #[test]
    fn retired_compaction_section_still_loads_and_validates() {
        let p: MemoryPolicy =
            toml::from_str("[compaction]\nenabled = true\nmin_cluster = 1\nsimilarity = 2.0\n")
                .expect("a retired [compaction] section must keep loading");
        assert_eq!(p.compaction.min_cluster, 1);
        p.validate()
            .expect("a retired [compaction] section is not validated");
    }

    #[test]
    fn env_overrides_apply() {
        let _lock = crate::core::data_dir::test_env_lock();

        let prev_facts = std::env::var("LEAN_CTX_KNOWLEDGE_MAX_FACTS").ok();
        let prev_stale = std::env::var("LEAN_CTX_LIFECYCLE_STALE_DAYS").ok();
        let prev_rep = std::env::var("LEAN_CTX_PROCEDURAL_MIN_REPETITIONS").ok();
        let prev_eps = std::env::var("LEAN_CTX_EPISODIC_MAX_EPISODES").ok();

        crate::test_env::set_var("LEAN_CTX_KNOWLEDGE_MAX_FACTS", "123");
        crate::test_env::set_var("LEAN_CTX_LIFECYCLE_STALE_DAYS", "7");
        crate::test_env::set_var("LEAN_CTX_PROCEDURAL_MIN_REPETITIONS", "4");
        crate::test_env::set_var("LEAN_CTX_EPISODIC_MAX_EPISODES", "7");

        let mut p = MemoryPolicy::default();
        p.apply_env_overrides();

        // The fact cap is gone: its env var no longer sets anything.
        assert_eq!(p.knowledge.max_facts, None);
        assert_eq!(p.lifecycle.stale_days, 7);
        // The episode and procedure memory is retired: their env vars are ignored.
        assert_eq!(p.procedural.min_repetitions, 3);
        assert_eq!(p.episodic.max_episodes, 500);

        restore_env("LEAN_CTX_KNOWLEDGE_MAX_FACTS", prev_facts);
        restore_env("LEAN_CTX_LIFECYCLE_STALE_DAYS", prev_stale);
        restore_env("LEAN_CTX_PROCEDURAL_MIN_REPETITIONS", prev_rep);
        restore_env("LEAN_CTX_EPISODIC_MAX_EPISODES", prev_eps);
    }

    #[test]
    fn validate_rejects_invalid_values() {
        let mut p = MemoryPolicy::default();
        p.knowledge.max_patterns = 0;
        assert!(p.validate().is_err());

        // The ignored fact cap never fails validation, even at 0.
        let mut p = MemoryPolicy::default();
        p.knowledge.max_facts = Some(0);
        assert!(p.validate().is_ok());

        let mut p = MemoryPolicy::default();
        p.lifecycle.decay_rate = 2.0;
        assert!(p.validate().is_err());
    }

    #[test]
    fn retired_episodic_and_procedural_sections_still_load_and_validate() {
        let p: MemoryPolicy = toml::from_str(
            "[episodic]\nmax_episodes = 0\n[procedural]\nmin_sequence_len = 1\nmax_procedures = 0\n",
        )
        .expect("retired [episodic]/[procedural] sections must keep loading");
        assert_eq!(p.episodic.max_episodes, 0);
        assert_eq!(p.procedural.min_sequence_len, 1);
        p.validate()
            .expect("retired [episodic]/[procedural] sections are not validated");
    }
}