diff --git a/CHANGELOG.md b/CHANGELOG.md
index a4210ea8f..d6b8c945a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -23,6 +23,11 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
 ### Changed
 
+- config: enable temporal decay, MMR, and importance scoring by default in semantic memory; existing configs with explicit `enabled = false` are unaffected (#2101)
+- config: change default vector backend from Qdrant to SQLite — zero-dependency out-of-box experience; set `vector_backend = "qdrant"` to revert (#2101)
+- config: enable anomaly detection, audit logging, and cost tracking by default; `max_daily_cents = 0` (unlimited) — cost is tracked but not capped (#2101)
+- config: enable `autosave_assistant` by default (`min_length = 20`); assistant responses are now persisted to semantic memory unless explicitly disabled (#2101)
+
 - refactor(zeph-llm): remove redundant `schema` feature gate — `schemars` is now a mandatory dependency of `zeph-llm`; all `#[cfg(feature = "schema")]` / `#[cfg_attr(feature = "schema", ...)]` annotations removed; `chat_typed`, `chat_typed_erased`, structured output types, and the `extractor` module are always compiled (#2100)
 - Promote `scheduler` and `guardrail` features to the default feature set; users with `default-features = false` are unaffected
 
diff --git a/config/default.toml b/config/default.toml
index 80eaa678a..4824d3b09 100644
--- a/config/default.toml
+++ b/config/default.toml
@@ -227,13 +227,13 @@ prune_protect_tokens = 40000
 # Minimum relevance score for cross-session memory results (0.0-1.0)
 cross_session_score_threshold = 0.35
 # Vector backend: "qdrant" (external) or "sqlite" (embedded, zero-dependency)
-# vector_backend = "qdrant"
+vector_backend = "sqlite"
 # Token safety margin multiplier for compaction budget (must be > 0)
 # token_safety_margin = 1.0
 # Redact credentials from LLM context before sending
 # redact_credentials = true
 # Auto-save assistant responses to semantic memory
-# autosave_assistant = false
+autosave_assistant = true
 # Minimum character length for autosave (shorter responses skip embedding)
 # autosave_min_length = 20
 # Store a lightweight session summary on shutdown when no hard compaction fired
@@ -270,14 +270,14 @@ recall_limit = 5
 vector_weight = 0.7
 keyword_weight = 0.3
 # Temporal decay: penalize older memories by age
-# temporal_decay_enabled = false
+temporal_decay_enabled = true
 # temporal_decay_half_life_days = 30
 # MMR re-ranking: diversify recall results
-# mmr_enabled = false
+mmr_enabled = true
 # mmr_lambda = 0.7
 # Write-time importance scoring: boost recall rank for messages with explicit markers (#2021)
-# importance_enabled = false
-# importance_weight = 0.15
+importance_enabled = true
+importance_weight = 0.15
 
 # Code RAG: AST-based code indexing and hybrid retrieval
 # Requires Qdrant for semantic retrieval; tree-sitter grammars are always available
@@ -364,9 +364,9 @@ max_dynamic_servers = 10
 
 [cost]
 # Track LLM API costs and enforce daily budget
-enabled = false
+enabled = true
 # Maximum daily spend in cents (0 = unlimited)
-max_daily_cents = 500
+max_daily_cents = 0
 
 [observability]
 # Tracing exporter: "" (disabled) or "otlp" (requires otel feature)
@@ -462,7 +462,7 @@ max_overflow_bytes = 10485760
 
 [tools.audit]
 # Enable audit logging for tool executions
-enabled = false
+enabled = true
 # Audit destination: "stdout" or file path (e.g., "./data/audit.jsonl")
 destination = "stdout"
 
@@ -487,7 +487,7 @@ default_effect = "deny"
 
 [tools.anomaly]
 # Enable sliding-window anomaly detection for tool execution errors
-enabled = false
+enabled = true
 # Number of recent tool calls to track in the window
 window_size = 10
 # Error ratio threshold for warning alerts (0.0-1.0)
diff --git a/crates/zeph-config/config/default.toml b/crates/zeph-config/config/default.toml
index 35e5ca429..44b606f5a 100644
--- a/crates/zeph-config/config/default.toml
+++ b/crates/zeph-config/config/default.toml
@@ -225,13 +225,13 @@ prune_protect_tokens = 40000
 # Minimum relevance score for cross-session memory results (0.0-1.0)
 cross_session_score_threshold = 0.35
 # Vector backend: "qdrant" (external) or "sqlite" (embedded, zero-dependency)
-# vector_backend = "qdrant"
+vector_backend = "sqlite"
 # Token safety margin multiplier for compaction budget (must be > 0)
 # token_safety_margin = 1.0
 # Redact credentials from LLM context before sending
 # redact_credentials = true
 # Auto-save assistant responses to semantic memory
-# autosave_assistant = false
+autosave_assistant = true
 # Minimum character length for autosave (shorter responses skip embedding)
 # autosave_min_length = 20
 # Use structured anchored summaries for context compaction (experimental, off by default)
@@ -264,11 +264,14 @@ recall_limit = 5
 vector_weight = 0.7
 keyword_weight = 0.3
 # Temporal decay: penalize older memories by age
-# temporal_decay_enabled = false
+temporal_decay_enabled = true
 # temporal_decay_half_life_days = 30
 # MMR re-ranking: diversify recall results
-# mmr_enabled = false
+mmr_enabled = true
 # mmr_lambda = 0.7
+# Write-time importance scoring: boost recall rank for messages with explicit markers (#2021)
+importance_enabled = true
+importance_weight = 0.15
 
 # Code RAG: AST-based code indexing and hybrid retrieval
 # Requires Qdrant for semantic retrieval; tree-sitter grammars are always available
@@ -334,9 +337,9 @@ max_dynamic_servers = 10
 
 [cost]
 # Track LLM API costs and enforce daily budget
-enabled = false
+enabled = true
 # Maximum daily spend in cents (0 = unlimited)
-max_daily_cents = 500
+max_daily_cents = 0
 
 [observability]
 # Tracing exporter: "" (disabled) or "otlp" (requires otel feature)
@@ -432,7 +435,7 @@ max_overflow_bytes = 10485760
 
 [tools.audit]
 # Enable audit logging for tool executions
-enabled = false
+enabled = true
 # Audit destination: "stdout" or file path (e.g., "./data/audit.jsonl")
 destination = "stdout"
 
@@ -446,7 +449,7 @@ default_effect = "deny"
 
 [tools.anomaly]
 # Enable sliding-window anomaly detection for tool execution errors
-enabled = false
+enabled = true
 # Number of recent tool calls to track in the window
 window_size = 10
 # Error ratio threshold for warning alerts (0.0-1.0)
diff --git a/crates/zeph-config/src/features.rs b/crates/zeph-config/src/features.rs
index 90f15a757..76109933e 100644
--- a/crates/zeph-config/src/features.rs
+++ b/crates/zeph-config/src/features.rs
@@ -56,7 +56,7 @@ fn default_vault_backend() -> String {
 }
 
 fn default_max_daily_cents() -> u32 {
-    500
+    0
 }
 
 fn default_otlp_endpoint() -> String {
@@ -180,7 +180,7 @@ impl Default for VaultConfig {
 
 #[derive(Debug, Deserialize, Serialize)]
 pub struct CostConfig {
-    #[serde(default)]
+    #[serde(default = "default_true")]
     pub enabled: bool,
     #[serde(default = "default_max_daily_cents")]
     pub max_daily_cents: u32,
@@ -189,7 +189,7 @@ pub struct CostConfig {
 impl Default for CostConfig {
     fn default() -> Self {
         Self {
-            enabled: false,
+            enabled: true,
             max_daily_cents: default_max_daily_cents(),
         }
     }
diff --git a/crates/zeph-config/src/memory.rs b/crates/zeph-config/src/memory.rs
index 1944027e9..68dc627a2 100644
--- a/crates/zeph-config/src/memory.rs
+++ b/crates/zeph-config/src/memory.rs
@@ -3,7 +3,7 @@
 
 use serde::{Deserialize, Serialize};
 
-use crate::defaults::default_sqlite_path_field;
+use crate::defaults::{default_sqlite_path_field, default_true};
 
 fn default_sqlite_pool_size() -> u32 {
     5
@@ -504,8 +504,8 @@ impl Default for NoteLinkingConfig {
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Default, Deserialize, Serialize)]
 #[serde(rename_all = "lowercase")]
 pub enum VectorBackend {
-    #[default]
     Qdrant,
+    #[default]
     Sqlite,
 }
 
@@ -558,7 +558,7 @@ pub struct MemoryConfig {
     pub token_safety_margin: f32,
     #[serde(default = "default_redact_credentials")]
     pub redact_credentials: bool,
-    #[serde(default)]
+    #[serde(default = "default_true")]
     pub autosave_assistant: bool,
     #[serde(default = "default_autosave_min_length")]
     pub autosave_min_length: usize,
@@ -674,15 +674,15 @@ pub struct SemanticConfig {
     pub vector_weight: f64,
     #[serde(default = "default_keyword_weight")]
     pub keyword_weight: f64,
-    #[serde(default)]
+    #[serde(default = "default_true")]
     pub temporal_decay_enabled: bool,
     #[serde(default = "default_temporal_decay_half_life_days")]
     pub temporal_decay_half_life_days: u32,
-    #[serde(default)]
+    #[serde(default = "default_true")]
     pub mmr_enabled: bool,
     #[serde(default = "default_mmr_lambda")]
     pub mmr_lambda: f32,
-    #[serde(default)]
+    #[serde(default = "default_true")]
     pub importance_enabled: bool,
     #[serde(
         default = "default_importance_weight",
@@ -698,11 +698,11 @@ impl Default for SemanticConfig {
             recall_limit: default_recall_limit(),
             vector_weight: default_vector_weight(),
             keyword_weight: default_keyword_weight(),
-            temporal_decay_enabled: false,
+            temporal_decay_enabled: true,
             temporal_decay_half_life_days: default_temporal_decay_half_life_days(),
-            mmr_enabled: false,
+            mmr_enabled: true,
             mmr_lambda: default_mmr_lambda(),
-            importance_enabled: false,
+            importance_enabled: true,
             importance_weight: default_importance_weight(),
         }
     }
diff --git a/crates/zeph-config/src/root.rs b/crates/zeph-config/src/root.rs
index c1a53df09..f226c0cbf 100644
--- a/crates/zeph-config/src/root.rs
+++ b/crates/zeph-config/src/root.rs
@@ -183,7 +183,7 @@ impl Default for Config {
                 vector_backend: VectorBackend::default(),
                 token_safety_margin: 1.0,
                 redact_credentials: true,
-                autosave_assistant: false,
+                autosave_assistant: true,
                 autosave_min_length: 20,
                 tool_call_cutoff: 6,
                 sqlite_pool_size: 5,
diff --git a/crates/zeph-core/src/agent/builder.rs b/crates/zeph-core/src/agent/builder.rs
index 8ed731684..5db4012a0 100644
--- a/crates/zeph-core/src/agent/builder.rs
+++ b/crates/zeph-core/src/agent/builder.rs
@@ -1229,7 +1229,8 @@ mod tests {
     fn apply_session_config_skips_anomaly_detector_when_disabled() {
         use crate::config::Config;
 
-        let config = Config::default(); // anomaly.enabled defaults to false
+        let mut config = Config::default();
+        config.tools.anomaly.enabled = false; // explicitly disable to test the disabled path
         let session_cfg = AgentSessionConfig::from_config(&config, 100_000);
         assert!(!session_cfg.anomaly_config.enabled);
 
diff --git a/crates/zeph-core/src/cost.rs b/crates/zeph-core/src/cost.rs
index 79ff7a2d6..788abf5c9 100644
--- a/crates/zeph-core/src/cost.rs
+++ b/crates/zeph-core/src/cost.rs
@@ -204,7 +204,7 @@ impl CostTracker {
             state.spent_cents = 0.0;
             state.day = today;
         }
-        if state.spent_cents >= self.max_daily_cents {
+        if self.max_daily_cents > 0.0 && state.spent_cents >= self.max_daily_cents {
             return Err(BudgetExhausted {
                 spent_cents: state.spent_cents,
                 budget_cents: self.max_daily_cents,
diff --git a/crates/zeph-tools/src/config.rs b/crates/zeph-tools/src/config.rs
index dd31ec35c..3b3b6aae5 100644
--- a/crates/zeph-tools/src/config.rs
+++ b/crates/zeph-tools/src/config.rs
@@ -89,7 +89,7 @@ fn default_anomaly_critical_threshold() -> f64 {
 /// Configuration for the sliding-window anomaly detector.
 #[derive(Debug, Clone, Deserialize, Serialize)]
 pub struct AnomalyConfig {
-    #[serde(default)]
+    #[serde(default = "default_true")]
     pub enabled: bool,
     #[serde(default = "default_anomaly_window")]
     pub window_size: usize,
@@ -102,7 +102,7 @@ pub struct AnomalyConfig {
 impl Default for AnomalyConfig {
     fn default() -> Self {
         Self {
-            enabled: false,
+            enabled: true,
             window_size: default_anomaly_window(),
             error_threshold: default_anomaly_error_threshold(),
             critical_threshold: default_anomaly_critical_threshold(),
@@ -284,7 +284,7 @@ pub struct ShellConfig {
 /// Configuration for audit logging of tool executions.
 #[derive(Debug, Deserialize, Serialize)]
 pub struct AuditConfig {
-    #[serde(default)]
+    #[serde(default = "default_true")]
     pub enabled: bool,
     #[serde(default = "default_audit_destination")]
     pub destination: String,
@@ -327,7 +327,7 @@ impl Default for ShellConfig {
 impl Default for AuditConfig {
     fn default() -> Self {
         Self {
-            enabled: false,
+            enabled: true,
             destination: default_audit_destination(),
         }
     }
@@ -401,7 +401,7 @@ mod tests {
         assert!(config.summarize_output);
         assert_eq!(config.shell.timeout, 30);
         assert!(config.shell.blocked_commands.is_empty());
-        assert!(!config.audit.enabled);
+        assert!(config.audit.enabled);
     }
 
     #[test]
@@ -440,7 +440,7 @@ mod tests {
         assert!(!config.shell.confirm_patterns.is_empty());
         assert_eq!(config.scrape.timeout, 15);
         assert_eq!(config.scrape.max_body_bytes, 4_194_304);
-        assert!(!config.audit.enabled);
+        assert!(config.audit.enabled);
         assert_eq!(config.audit.destination, "stdout");
         assert!(config.summarize_output);
     }
@@ -521,7 +521,7 @@ mod tests {
     #[test]
     fn default_audit_config() {
         let config = AuditConfig::default();
-        assert!(!config.enabled);
+        assert!(config.enabled);
         assert_eq!(config.destination, "stdout");
     }