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new file mode 100644
index 000000000..5d59c4985
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diff --git a/tooling/line-previewer/Cargo.toml b/tooling/line-previewer/Cargo.toml
new file mode 100644
index 000000000..74f03d3be
--- /dev/null
+++ b/tooling/line-previewer/Cargo.toml
@@ -0,0 +1,16 @@
+[package]
+name = "line-previewer"
+version = "0.1.0"
+edition = "2021"
+description = "CLI tool to preview dialogue/monologue line selection for a given game state."
+
+[[bin]]
+name = "line-previewer"
+path = "src/main.rs"
+
+[dependencies]
+serde = { version = "1", features = ["derive"] }
+serde_yaml = "0.9"
+clap = { version = "4", features = ["derive"] }
+rand = "0.9"
+rand_chacha = "0.9"
diff --git a/tooling/line-previewer/src/main.rs b/tooling/line-previewer/src/main.rs
new file mode 100644
index 000000000..27e952dbb
--- /dev/null
+++ b/tooling/line-previewer/src/main.rs
@@ -0,0 +1,234 @@
+//! line-previewer: CLI tool for previewing dialogue/monologue line selection.
+//!
+//! Answers: "Given this NPC state and player state, what line fires?"
+//! Authoring tool for content authors to test tag behavior without running the game.
+//! Implements the 4-layer dialogue selection pipeline (D-028) in standalone mode.
+
+use clap::{Parser, Subcommand};
+use std::path::PathBuf;
+
+mod pipeline;
+mod types;
+
+use pipeline::{
+    evaluate_dialogue, evaluate_monologue, print_coverage_report, print_dialogue_results,
+    print_monologue_results, DialogueContext, MonologueContext,
+};
+use types::{DialoguePool, MonologuePool};
+
+#[derive(Parser)]
+#[command(
+    name = "line-previewer",
+    about = "Preview dialogue/monologue line selection"
+)]
+struct Cli {
+    #[command(subcommand)]
+    command: Command,
+}
+
+#[derive(Subcommand)]
+enum Command {
+    /// Preview dialogue line selection
+    Dialogue {
+        /// Path to dialogue YAML file
+        #[arg(short, long)]
+        file: PathBuf,
+
+        /// Access tier(s): public, insider, authority, peer, hostile
+        #[arg(short, long, value_delimiter = ',')]
+        access: Vec<String>,
+
+        /// Trust level: surface, real, secret
+        #[arg(short, long, default_value = "surface")]
+        trust: String,
+
+        /// Active situation(s): arrival, shift_start, shift_end, etc.
+        #[arg(short, long, value_delimiter = ',')]
+        situation: Vec<String>,
+
+        /// Topic filter(s): colleague, routine, cargo, etc.
+        #[arg(long, value_delimiter = ',')]
+        topic: Vec<String>,
+
+        /// Mood filter(s): fond, comfortable, worried, etc.
+        #[arg(long, value_delimiter = ',')]
+        mood: Vec<String>,
+
+        /// Show detailed filter pass/fail for each line
+        #[arg(short, long)]
+        verbose: bool,
+
+        /// RNG seed for weighted selection (default: 42)
+        #[arg(long, default_value = "42")]
+        seed: u64,
+    },
+
+    /// Preview monologue line selection
+    Monologue {
+        /// Path to monologue YAML file
+        #[arg(short, long)]
+        file: PathBuf,
+
+        /// Character: smuggler or detective
+        #[arg(short, long)]
+        character: String,
+
+        /// Trigger type: enter_location, observe_npc, etc.
+        #[arg(short, long)]
+        trigger: String,
+
+        /// Known fact IDs (for prerequisite evaluation)
+        #[arg(long, value_delimiter = ',')]
+        known_facts: Vec<String>,
+
+        /// Show detailed prerequisite evaluation for each line
+        #[arg(short, long)]
+        verbose: bool,
+
+        /// RNG seed for weighted selection (default: 42)
+        #[arg(long, default_value = "42")]
+        seed: u64,
+    },
+
+    /// Show coverage report — which filter combinations have zero eligible lines
+    Coverage {
+        /// Path to dialogue or monologue YAML file
+        #[arg(short, long)]
+        file: PathBuf,
+    },
+
+    /// Preview a sequence of monologue lines (walk-through simulation)
+    Sequence {
+        /// Path to monologue YAML file
+        #[arg(short, long)]
+        file: PathBuf,
+
+        /// Character: smuggler or detective
+        #[arg(short, long)]
+        character: String,
+
+        /// Trigger sequence (comma-separated): enter_location,observe_npc,time_idle
+        #[arg(short, long, value_delimiter = ',')]
+        triggers: Vec<String>,
+
+        /// RNG seed (default: 42)
+        #[arg(long, default_value = "42")]
+        seed: u64,
+    },
+}
+
+fn main() {
+    let cli = Cli::parse();
+
+    match cli.command {
+        Command::Dialogue {
+            file,
+            access,
+            trust,
+            situation,
+            topic,
+            mood,
+            verbose,
+            seed,
+        } => {
+            let pool = load_dialogue(&file);
+            let ctx = DialogueContext {
+                access,
+                trust,
+                situation,
+                topic,
+                mood,
+                seed,
+            };
+            let results = evaluate_dialogue(&pool, &ctx);
+            print_dialogue_results(&results, verbose, seed);
+        }
+        Command::Monologue {
+            file,
+            character,
+            trigger,
+            known_facts,
+            verbose,
+            seed,
+        } => {
+            let pool = load_monologue(&file);
+            if pool.character != character {
+                eprintln!(
+                    "Warning: file character '{}' doesn't match requested '{}'",
+                    pool.character, character
+                );
+            }
+            let ctx = MonologueContext {
+                trigger,
+                known_facts,
+                seed,
+            };
+            let results = evaluate_monologue(&pool, &ctx);
+            print_monologue_results(&results, verbose, seed);
+        }
+        Command::Coverage { file } => {
+            let yaml_str = std::fs::read_to_string(&file).unwrap_or_else(|e| {
+                eprintln!("Error reading {}: {e}", file.display());
+                std::process::exit(1);
+            });
+            print_coverage_report(&yaml_str, &file);
+        }
+        Command::Sequence {
+            file,
+            character,
+            triggers,
+            seed,
+        } => {
+            let pool = load_monologue(&file);
+            if pool.character != character {
+                eprintln!(
+                    "Warning: file character '{}' doesn't match requested '{}'",
+                    pool.character, character
+                );
+            }
+            println!("[Sequence: {} — {}]", file.display(), character);
+            let mut used_ids: Vec<String> = Vec::new();
+            for (i, trigger) in triggers.iter().enumerate() {
+                let ctx = MonologueContext {
+                    trigger: trigger.clone(),
+                    known_facts: vec![],
+                    seed: seed.wrapping_add(i as u64),
+                };
+                let results = evaluate_monologue(&pool, &ctx);
+                // Filter out recently used lines
+                let eligible: Vec<_> = results
+                    .iter()
+                    .filter(|r| r.passed && !used_ids.contains(&r.line_id))
+                    .collect();
+                if let Some(selected) = eligible.first() {
+                    println!("{}. ({}) {:?}", i + 1, trigger, selected.text);
+                    used_ids.push(selected.line_id.clone());
+                } else {
+                    println!("{}. ({}) [no eligible line]", i + 1, trigger);
+                }
+            }
+        }
+    }
+}
+
+fn load_dialogue(path: &PathBuf) -> DialoguePool {
+    let yaml_str = std::fs::read_to_string(path).unwrap_or_else(|e| {
+        eprintln!("Error reading {}: {e}", path.display());
+        std::process::exit(1);
+    });
+    serde_yaml::from_str(&yaml_str).unwrap_or_else(|e| {
+        eprintln!("Error parsing dialogue YAML: {e}");
+        std::process::exit(1);
+    })
+}
+
+fn load_monologue(path: &PathBuf) -> MonologuePool {
+    let yaml_str = std::fs::read_to_string(path).unwrap_or_else(|e| {
+        eprintln!("Error reading {}: {e}", path.display());
+        std::process::exit(1);
+    });
+    serde_yaml::from_str(&yaml_str).unwrap_or_else(|e| {
+        eprintln!("Error parsing monologue YAML: {e}");
+        std::process::exit(1);
+    })
+}
diff --git a/tooling/line-previewer/src/pipeline.rs b/tooling/line-previewer/src/pipeline.rs
new file mode 100644
index 000000000..3a8025b3f
--- /dev/null
+++ b/tooling/line-previewer/src/pipeline.rs
@@ -0,0 +1,585 @@
+//! 4-layer dialogue selection pipeline (D-028) and monologue trigger evaluation.
+//!
+//! Layer 1: Access tier filter (hard filter)
+//! Layer 2: Situation filter (hard filter)
+//! Layer 3: Trust level filter (hard filter)
+//! Layer 4: Weighted selection by topic + mood match
+
+use crate::types::{DialogueLine, DialoguePool, MonologueLine, MonologuePool};
+use rand::prelude::*;
+use rand_chacha::ChaCha20Rng;
+use std::path::Path;
+
+// --- Dialogue pipeline ---
+
+pub struct DialogueContext {
+    pub access: Vec<String>,
+    pub trust: String,
+    pub situation: Vec<String>,
+    pub topic: Vec<String>,
+    pub mood: Vec<String>,
+    #[allow(dead_code)]
+    pub seed: u64,
+}
+
+pub struct DialogueResult {
+    pub line_id: String,
+    pub text: String,
+    pub passed: bool,
+    pub weight: f64,
+    pub access_pass: bool,
+    pub trust_pass: bool,
+    pub situation_pass: bool,
+    pub topic_match: f64,
+    pub mood_match: f64,
+    pub access_detail: String,
+    pub trust_detail: String,
+    pub situation_detail: String,
+}
+
+pub fn evaluate_dialogue(pool: &DialoguePool, ctx: &DialogueContext) -> Vec<DialogueResult> {
+    pool.lines
+        .iter()
+        .map(|line| evaluate_dialogue_line(line, ctx))
+        .collect()
+}
+
+fn evaluate_dialogue_line(line: &DialogueLine, ctx: &DialogueContext) -> DialogueResult {
+    // Layer 1: Access tier — at least one of the player's access tiers must match
+    let access_pass = line.access.iter().any(|a| ctx.access.contains(a));
+    let access_detail = if access_pass {
+        let matched: Vec<_> = line
+            .access
+            .iter()
+            .filter(|a| ctx.access.contains(a))
+            .collect();
+        format!(
+            "matched: {}",
+            matched
+                .iter()
+                .map(|s| s.as_str())
+                .collect::<Vec<_>>()
+                .join(", ")
+        )
+    } else {
+        format!(
+            "line requires [{}], player has [{}]",
+            line.access.join(", "),
+            ctx.access.join(", ")
+        )
+    };
+
+    // Layer 2: Situation — at least one active situation must match
+    let situation_pass = if ctx.situation.is_empty() {
+        true // no situation filter = all situations match
+    } else {
+        line.situation.iter().any(|s| ctx.situation.contains(s))
+    };
+    let situation_detail = if situation_pass {
+        if ctx.situation.is_empty() {
+            "no filter applied".to_string()
+        } else {
+            let matched: Vec<_> = line
+                .situation
+                .iter()
+                .filter(|s| ctx.situation.contains(s))
+                .collect();
+            format!(
+                "matched: {}",
+                matched
+                    .iter()
+                    .map(|s| s.as_str())
+                    .collect::<Vec<_>>()
+                    .join(", ")
+            )
+        }
+    } else {
+        format!(
+            "line requires [{}], active: [{}]",
+            line.situation.join(", "),
+            ctx.situation.join(", ")
+        )
+    };
+
+    // Layer 3: Trust — line's trust level must be <= player's trust level
+    let trust_order = trust_rank(&line.trust);
+    let player_trust = trust_rank(&ctx.trust);
+    let trust_pass = trust_order <= player_trust;
+    let trust_detail = if trust_pass {
+        format!("line={} <= player={}", line.trust, ctx.trust)
+    } else {
+        format!(
+            "line requires {} but player only has {}",
+            line.trust, ctx.trust
+        )
+    };
+
+    // Layer 4: Weighted selection by topic + mood overlap
+    let topic_match = if ctx.topic.is_empty() || line.topic.is_empty() {
+        0.5 // neutral weight when no topic filter
+    } else {
+        let matches = line.topic.iter().filter(|t| ctx.topic.contains(t)).count();
+        if matches > 0 {
+            0.5 + 0.5 * (matches as f64 / line.topic.len().max(1) as f64)
+        } else {
+            0.3 // slight penalty for topic mismatch but not exclusion
+        }
+    };
+
+    let mood_match = if ctx.mood.is_empty() || line.mood.is_empty() {
+        0.5
+    } else {
+        let matches = line.mood.iter().filter(|m| ctx.mood.contains(m)).count();
+        if matches > 0 {
+            0.5 + 0.5 * (matches as f64 / line.mood.len().max(1) as f64)
+        } else {
+            0.3
+        }
+    };
+
+    let passed = access_pass && situation_pass && trust_pass;
+    let weight = if passed {
+        topic_match * mood_match
+    } else {
+        0.0
+    };
+
+    DialogueResult {
+        line_id: line.id.clone(),
+        text: line.text.clone(),
+        passed,
+        weight,
+        access_pass,
+        trust_pass,
+        situation_pass,
+        topic_match,
+        mood_match,
+        access_detail,
+        trust_detail,
+        situation_detail,
+    }
+}
+
+fn trust_rank(trust: &str) -> u8 {
+    match trust {
+        "surface" => 0,
+        "real" => 1,
+        "secret" => 2,
+        _ => 0,
+    }
+}
+
+pub fn print_dialogue_results(results: &[DialogueResult], verbose: bool, seed: u64) {
+    let passing: Vec<_> = results.iter().filter(|r| r.passed).collect();
+    let failing: Vec<_> = results.iter().filter(|r| !r.passed).collect();
+
+    println!(
+        "Dialogue evaluation: {} total, {} eligible, {} filtered out\n",
+        results.len(),
+        passing.len(),
+        failing.len()
+    );
+
+    for r in &passing {
+        println!("  [PASS] {}: {:?}", r.line_id, r.text);
+        println!(
+            "         weight={:.2}  topic={:.2}  mood={:.2}",
+            r.weight, r.topic_match, r.mood_match
+        );
+        if verbose {
+            println!("         access: {}", r.access_detail);
+            println!("         trust: {}", r.trust_detail);
+            println!("         situation: {}", r.situation_detail);
+        }
+    }
+
+    if verbose && !failing.is_empty() {
+        println!("\n  Filtered out:");
+        for r in &failing {
+            let reasons: Vec<&str> = [
+                if !r.access_pass { Some("access") } else { None },
+                if !r.trust_pass { Some("trust") } else { None },
+                if !r.situation_pass {
+                    Some("situation")
+                } else {
+                    None
+                },
+            ]
+            .iter()
+            .filter_map(|x| *x)
+            .collect();
+
+            println!(
+                "  [FAIL] {}: {:?}  (failed: {})",
+                r.line_id,
+                r.text,
+                reasons.join(", ")
+            );
+            if !r.access_pass {
+                println!("         access: {}", r.access_detail);
+            }
+            if !r.trust_pass {
+                println!("         trust: {}", r.trust_detail);
+            }
+            if !r.situation_pass {
+                println!("         situation: {}", r.situation_detail);
+            }
+        }
+    }
+
+    // Weighted selection
+    if !passing.is_empty() {
+        let total_weight: f64 = passing.iter().map(|r| r.weight).sum();
+        if total_weight > 0.0 {
+            let mut rng = ChaCha20Rng::seed_from_u64(seed);
+            let roll: f64 = rng.random::<f64>() * total_weight;
+            let mut cumulative = 0.0;
+            for r in &passing {
+                cumulative += r.weight;
+                if cumulative >= roll {
+                    println!(
+                        "\n  Selected: {} (weight={:.2}/{:.2})",
+                        r.line_id, r.weight, total_weight
+                    );
+                    break;
+                }
+            }
+        }
+    } else {
+        println!("\n  No eligible lines for this context.");
+    }
+}
+
+// --- Monologue pipeline ---
+
+pub struct MonologueContext {
+    pub trigger: String,
+    pub known_facts: Vec<String>,
+    #[allow(dead_code)]
+    pub seed: u64,
+}
+
+pub struct MonologueResult {
+    pub line_id: String,
+    pub text: String,
+    pub passed: bool,
+    pub trigger_pass: bool,
+    pub prereq_pass: bool,
+    pub priority: i32,
+    pub trigger_detail: String,
+    pub prereq_detail: String,
+}
+
+pub fn evaluate_monologue(pool: &MonologuePool, ctx: &MonologueContext) -> Vec<MonologueResult> {
+    let mut results: Vec<_> = pool
+        .lines
+        .iter()
+        .map(|line| evaluate_monologue_line(line, ctx))
+        .collect();
+
+    // Sort by priority (higher first), then by line_id for determinism
+    results.sort_by(|a, b| {
+        b.priority
+            .cmp(&a.priority)
+            .then_with(|| a.line_id.cmp(&b.line_id))
+    });
+
+    results
+}
+
+fn evaluate_monologue_line(line: &MonologueLine, ctx: &MonologueContext) -> MonologueResult {
+    // Trigger match
+    let trigger_pass = line.trigger == ctx.trigger;
+    let trigger_detail = if trigger_pass {
+        format!("matched: {}", ctx.trigger)
+    } else {
+        format!("line={}, context={}", line.trigger, ctx.trigger)
+    };
+
+    // Prerequisite evaluation
+    let (prereq_pass, prereq_detail) = if let Some(ref prereqs) = line.prerequisites {
+        evaluate_prerequisites(prereqs, &ctx.known_facts)
+    } else {
+        (true, "no prerequisites".to_string())
+    };
+
+    let passed = trigger_pass && prereq_pass;
+    let priority = line.priority.unwrap_or(5);
+
+    MonologueResult {
+        line_id: line.id.clone(),
+        text: line.text.clone(),
+        passed,
+        trigger_pass,
+        prereq_pass,
+        priority,
+        trigger_detail,
+        prereq_detail,
+    }
+}
+
+fn evaluate_prerequisites(
+    prereqs: &crate::types::Prerequisites,
+    known_facts: &[String],
+) -> (bool, String) {
+    let mut details = Vec::new();
+    let mut all_pass = true;
+
+    for fact_req in &prereqs.facts {
+        let has_fact = known_facts.contains(&fact_req.fact_id);
+        if has_fact {
+            details.push(format!(
+                "fact:{} >= {} [PASS]",
+                fact_req.fact_id, fact_req.min_confidence
+            ));
+        } else {
+            details.push(format!(
+                "fact:{} >= {} [FAIL: not known]",
+                fact_req.fact_id, fact_req.min_confidence
+            ));
+            all_pass = false;
+        }
+    }
+
+    // Entity attributes and relationships are not yet checkable without full game state
+    if !prereqs.entity_attributes.is_empty() {
+        details.push(format!(
+            "{} entity_attribute prereqs (skipped: no game state)",
+            prereqs.entity_attributes.len()
+        ));
+    }
+
+    if prereqs.relationship.is_some() {
+        details.push("relationship prereq (skipped: no game state)".to_string());
+    }
+
+    if details.is_empty() {
+        (true, "no prerequisites".to_string())
+    } else {
+        (all_pass, details.join("; "))
+    }
+}
+
+pub fn print_monologue_results(results: &[MonologueResult], verbose: bool, _seed: u64) {
+    let passing: Vec<_> = results.iter().filter(|r| r.passed).collect();
+    let failing: Vec<_> = results.iter().filter(|r| !r.passed).collect();
+
+    println!(
+        "Monologue evaluation: {} total, {} eligible, {} filtered out\n",
+        results.len(),
+        passing.len(),
+        failing.len()
+    );
+
+    for r in &passing {
+        println!(
+            "  [PASS] {} (priority={}): {:?}",
+            r.line_id, r.priority, r.text
+        );
+        if verbose {
+            println!("         trigger: {}", r.trigger_detail);
+            println!("         prereqs: {}", r.prereq_detail);
+        }
+    }
+
+    if verbose && !failing.is_empty() {
+        println!("\n  Filtered out:");
+        for r in &failing {
+            let reasons: Vec<&str> = [
+                if !r.trigger_pass {
+                    Some("trigger")
+                } else {
+                    None
+                },
+                if !r.prereq_pass {
+                    Some("prerequisites")
+                } else {
+                    None
+                },
+            ]
+            .iter()
+            .filter_map(|x| *x)
+            .collect();
+
+            println!(
+                "  [FAIL] {}: {:?}  (failed: {})",
+                r.line_id,
+                r.text,
+                reasons.join(", ")
+            );
+            if !r.trigger_pass {
+                println!("         trigger: {}", r.trigger_detail);
+            }
+            if !r.prereq_pass {
+                println!("         prereqs: {}", r.prereq_detail);
+            }
+        }
+    }
+
+    // Selection: highest priority eligible line
+    if let Some(selected) = passing.first() {
+        println!(
+            "\n  Selected: {} (priority={})",
+            selected.line_id, selected.priority
+        );
+    } else {
+        println!("\n  No eligible lines for this trigger.");
+    }
+}
+
+// --- Coverage report ---
+
+pub fn print_coverage_report(yaml_str: &str, path: &Path) {
+    // Try dialogue first, then monologue
+    if let Ok(pool) = serde_yaml::from_str::<DialoguePool>(yaml_str) {
+        print_dialogue_coverage(&pool, path);
+    } else if let Ok(pool) = serde_yaml::from_str::<MonologuePool>(yaml_str) {
+        print_monologue_coverage(&pool, path);
+    } else {
+        eprintln!("Error: file is neither dialogue nor monologue YAML");
+        std::process::exit(1);
+    }
+}
+
+fn print_dialogue_coverage(pool: &DialoguePool, path: &Path) {
+    let access_tiers = ["public", "insider", "authority", "peer", "hostile"];
+    let trust_levels = ["surface", "real", "secret"];
+    let situations = [
+        "arrival",
+        "shift_start",
+        "shift_end",
+        "shift_transition",
+        "bar_evening",
+        "night_shift",
+        "investigation",
+        "confrontation",
+        "social",
+        "alone",
+        "emergency",
+        "routine",
+        "observation",
+    ];
+
+    println!(
+        "Coverage report: {} (role: {}, location: {})\n",
+        path.display(),
+        pool.role,
+        pool.location
+    );
+
+    let mut gaps = Vec::new();
+
+    for access in &access_tiers {
+        for trust in &trust_levels {
+            for situation in &situations {
+                let eligible = pool
+                    .lines
+                    .iter()
+                    .filter(|line| {
+                        line.access.iter().any(|a| a == access)
+                            && trust_rank(&line.trust) <= trust_rank(trust)
+                            && line.situation.iter().any(|s| s == situation)
+                    })
+                    .count();
+
+                if eligible == 0 {
+                    gaps.push(format!(
+                        "  access={:<10} trust={:<8} situation={:<18} -> 0 lines",
+                        access, trust, situation
+                    ));
+                }
+            }
+        }
+    }
+
+    if gaps.is_empty() {
+        println!("  Full coverage! Every access/trust/situation combination has at least one eligible line.");
+    } else {
+        println!(
+            "  {} gaps found (access/trust/situation combos with zero eligible lines):\n",
+            gaps.len()
+        );
+        // Show first 20 gaps
+        for gap in gaps.iter().take(20) {
+            println!("{gap}");
+        }
+        if gaps.len() > 20 {
+            println!("  ... and {} more", gaps.len() - 20);
+        }
+    }
+
+    println!(
+        "\n  Total lines: {}, Access tiers used: {:?}, Trust levels used: {:?}",
+        pool.lines.len(),
+        pool.lines
+            .iter()
+            .flat_map(|l| l.access.iter())
+            .collect::<std::collections::BTreeSet<_>>(),
+        pool.lines
+            .iter()
+            .map(|l| l.trust.as_str())
+            .collect::<std::collections::BTreeSet<_>>(),
+    );
+}
+
+fn print_monologue_coverage(pool: &MonologuePool, path: &Path) {
+    let triggers = [
+        "enter_location",
+        "observe_npc",
+        "hear_sound",
+        "observe_anomaly",
+        "post_conversation",
+        "discover_evidence",
+        "witness_interaction",
+        "time_idle",
+        "return_visit",
+    ];
+
+    println!(
+        "Coverage report: {} (character: {}, location: {})\n",
+        path.display(),
+        pool.character,
+        pool.location
+    );
+
+    let mut covered = Vec::new();
+    let mut uncovered = Vec::new();
+
+    for trigger in &triggers {
+        let count = pool
+            .lines
+            .iter()
+            .filter(|line| line.trigger == *trigger)
+            .count();
+        if count > 0 {
+            covered.push(format!("  {:<25} {} lines", trigger, count));
+        } else {
+            uncovered.push(format!("  {:<25} 0 lines", trigger));
+        }
+    }
+
+    if !covered.is_empty() {
+        println!("  Covered triggers:");
+        for line in &covered {
+            println!("{line}");
+        }
+    }
+
+    if !uncovered.is_empty() {
+        println!("\n  Uncovered triggers:");
+        for line in &uncovered {
+            println!("{line}");
+        }
+    }
+
+    let with_prereqs = pool
+        .lines
+        .iter()
+        .filter(|l| l.prerequisites.is_some())
+        .count();
+    println!(
+        "\n  Total lines: {}, With prerequisites: {}",
+        pool.lines.len(),
+        with_prereqs
+    );
+}
diff --git a/tooling/line-previewer/src/types.rs b/tooling/line-previewer/src/types.rs
new file mode 100644
index 000000000..afa76e975
--- /dev/null
+++ b/tooling/line-previewer/src/types.rs
@@ -0,0 +1,90 @@
+//! Content types for dialogue and monologue pools.
+//! Mirrors the JSON Schema definitions in content/_schema/.
+//! Fields that appear unused are required for YAML deserialization fidelity.
+
+#![allow(dead_code)]
+
+use serde::Deserialize;
+
+// --- Dialogue Pool ---
+
+#[derive(Debug, Deserialize)]
+pub struct DialoguePool {
+    pub location: String,
+    pub role: String,
+    pub lines: Vec<DialogueLine>,
+}
+
+#[derive(Debug, Deserialize)]
+pub struct DialogueLine {
+    pub id: String,
+    pub text: String,
+    pub role: String,
+    pub access: Vec<String>,
+    pub trust: String,
+    pub situation: Vec<String>,
+    #[serde(default)]
+    pub topic: Vec<String>,
+    #[serde(default)]
+    pub mood: Vec<String>,
+    #[serde(default)]
+    pub tags: Vec<String>,
+    pub knowledge_grant: Option<KnowledgeGrant>,
+}
+
+#[derive(Debug, Deserialize)]
+pub struct KnowledgeGrant {
+    pub fact_id: String,
+    pub confidence: String,
+}
+
+// --- Monologue Pool ---
+
+#[derive(Debug, Deserialize)]
+pub struct MonologuePool {
+    pub character: String,
+    pub location: String,
+    pub lines: Vec<MonologueLine>,
+}
+
+#[derive(Debug, Deserialize)]
+pub struct MonologueLine {
+    pub id: String,
+    pub text: String,
+    pub trigger: String,
+    pub prerequisites: Option<Prerequisites>,
+    #[serde(default)]
+    pub priority: Option<i32>,
+    #[serde(default)]
+    pub cooldown: Option<i32>,
+    #[serde(default)]
+    pub tags: Vec<String>,
+}
+
+#[derive(Debug, Deserialize)]
+pub struct Prerequisites {
+    #[serde(default)]
+    pub facts: Vec<FactPrerequisite>,
+    #[serde(default)]
+    pub entity_attributes: Vec<AttributePrerequisite>,
+    pub relationship: Option<RelationshipPrerequisite>,
+}
+
+#[derive(Debug, Deserialize)]
+pub struct FactPrerequisite {
+    pub fact_id: String,
+    pub min_confidence: String,
+}
+
+#[derive(Debug, Deserialize)]
+pub struct AttributePrerequisite {
+    pub entity: String,
+    pub key: String,
+    pub value: String,
+}
+
+#[derive(Debug, Deserialize)]
+pub struct RelationshipPrerequisite {
+    pub target: Option<String>,
+    pub state: Option<String>,
+}
diff --git a/tooling/line-previewer/test-fixtures/sample-dialogue.yaml b/tooling/line-previewer/test-fixtures/sample-dialogue.yaml
new file mode 100644
index 000000000..bcaae2733
--- /dev/null
+++ b/tooling/line-previewer/test-fixtures/sample-dialogue.yaml
@@ -0,0 +1,48 @@
+# Test fixture: dock-worker dialogue at The Terminal
+location: the-terminal
+role: dock-worker
+lines:
+  - id: "terminal_d_001"
+    text: "Morning. Manifest's ready if you need it."
+    role: dock-worker
+    access: [public, insider]
+    trust: surface
+    situation: [shift_start, routine]
+    topic: [routine, cargo]
+    mood: [comfortable]
+
+  - id: "terminal_d_002"
+    text: "You're new around here? Or just... visiting?"
+    role: dock-worker
+    access: [public, authority]
+    trust: surface
+    situation: [arrival, social]
+    topic: [colleague]
+    mood: [comfortable, suspicious]
+
+  - id: "terminal_d_003"
+    text: "Between you and me, the shift change is when things get... creative."
+    role: dock-worker
+    access: [insider]
+    trust: real
+    situation: [shift_transition, social]
+    topic: [cargo, money]
+    mood: [comfortable]
+
+  - id: "terminal_d_004"
+    text: "I know what's in those crates. And I know you know."
+    role: dock-worker
+    access: [insider]
+    trust: secret
+    situation: [confrontation, investigation]
+    topic: [cargo, trust, danger]
+    mood: [worried, conflicted]
+
+  - id: "terminal_d_005"
+    text: "Just another shift. Nothing special."
+    role: dock-worker
+    access: [public]
+    trust: surface
+    situation: [routine, shift_start, shift_end]
+    topic: [routine]
+    mood: [comfortable]
diff --git a/tooling/line-previewer/test-fixtures/sample-monologue.yaml b/tooling/line-previewer/test-fixtures/sample-monologue.yaml
new file mode 100644
index 000000000..a31d197d0
--- /dev/null
+++ b/tooling/line-previewer/test-fixtures/sample-monologue.yaml
@@ -0,0 +1,36 @@
+# Test fixture: smuggler monologue at The Terminal
+character: smuggler
+location: the-terminal
+lines:
+  - id: "terminal_m_s_001"
+    text: "The Terminal. Same hum, same faces, same game."
+    trigger: enter_location
+    priority: 5
+
+  - id: "terminal_m_s_002"
+    text: "Kael's at his station. Looks tense today."
+    trigger: observe_npc
+    priority: 7
+
+  - id: "terminal_m_s_003"
+    text: "That manifest doesn't add up. Kael knows something."
+    trigger: observe_anomaly
+    prerequisites:
+      facts:
+        - fact_id: manifest_discrepancy
+          min_confidence: suspects
+    priority: 9
+
+  - id: "terminal_m_s_004"
+    text: "Should check in on the next shipment. Can't be too careful."
+    trigger: time_idle
+    priority: 3
+
+  - id: "terminal_m_s_005"
+    text: "Something's different today. The usual rhythm is off."
+    trigger: enter_location
+    prerequisites:
+      facts:
+        - fact_id: ring_pressure_increasing
+          min_confidence: suspects
+    priority: 8