From 5b2b6a157c3959314742b17ce0b2ea4d55227b2b Mon Sep 17 00:00:00 2001
From: temiport25 <temiport25@users.noreply.github.com>
Date: Mon, 1 Jun 2026 11:06:07 +0100
Subject: [PATCH 1/2] feat(harness): add integration tests for fee_stats, error
 injection, and response delay

Closes #230
Closes #231
Closes #232
Closes #233

Co-Authored-By: temiport25 <temiport25@users.noreply.github.com>
---
 packages/devkit/src/cli/export.rs            | 13 ++--
 packages/devkit/src/cli/mod.rs               |  6 +-
 packages/devkit/src/cli/replay.rs            | 59 +++++++-----------
 packages/devkit/src/test_helpers/mod.rs      | 27 +++++----
 packages/devkit/tests/harness_integration.rs | 64 ++++++++++++++++++++
 5 files changed, 111 insertions(+), 58 deletions(-)
 create mode 100644 packages/devkit/tests/harness_integration.rs

diff --git a/packages/devkit/src/cli/export.rs b/packages/devkit/src/cli/export.rs
index 0eedccc..4202a2c 100644
--- a/packages/devkit/src/cli/export.rs
+++ b/packages/devkit/src/cli/export.rs
@@ -1,9 +1,7 @@
-use crate::simulation::fee_model::FeePoint;
+use crate::simulation::fee_model::FeePoint;
 use std::fmt::Write as FmtWrite;
 use std::path::{Path, PathBuf};
 
-use crate::simulation::fee_model::FeePoint;
-
 /// Arguments for the `export` subcommand.
 pub struct ExportArgs {
     /// Source SQLite database path.
@@ -56,7 +54,6 @@ impl Window {
 pub struct Export;
 
 impl Export {
-    /// Serialize fee points to CSV.
     /// Filter points by window relative to the latest timestamp.
     pub fn filter_window<'a>(points: &'a [FeePoint], window: Window) -> &'a [FeePoint] {
         match window.cutoff_seconds() {
@@ -116,6 +113,10 @@ mod tests {
         ]
     }
 
+    fn sample() -> Vec<FeePoint> {
+        vec![FeePoint { timestamp: 1000, fee: 100, ledger: 1, is_spike: false }]
+    }
+
     #[test]
     fn window_1h_filters() {
         let p = pts();
@@ -128,8 +129,6 @@ mod tests {
     fn window_all_keeps_all() {
         let p = pts();
         assert_eq!(Export::filter_window(&p, Window::All).len(), 2);
-    fn sample() -> Vec<FeePoint> {
-        vec![FeePoint { timestamp: 1000, fee: 100, ledger: 1, is_spike: false }]
     }
 
     #[test]
@@ -144,4 +143,4 @@ mod tests {
         assert!(json.starts_with('['));
         assert!(json.ends_with(']'));
     }
-}
\ No newline at end of file
+}
diff --git a/packages/devkit/src/cli/mod.rs b/packages/devkit/src/cli/mod.rs
index d8ea2a6..6e27d8b 100644
--- a/packages/devkit/src/cli/mod.rs
+++ b/packages/devkit/src/cli/mod.rs
@@ -2,6 +2,8 @@ pub mod benchmark;
 pub mod export;
 pub mod replay;
 
+use clap::{Parser, Subcommand};
+
 /// Arguments for the `simulate` subcommand.
 pub struct SimulateArgs {
     /// Base fee floor in stroops.
@@ -30,6 +32,8 @@ impl SimulateArgs {
             self.duration, self.base_fee, self.spike_prob
         );
     }
+}
+
 /// Arguments for the `mock` subcommand.
 pub struct MockArgs {
     /// Scenario to load (e.g. "normal", "congested", "spike").
@@ -55,7 +59,7 @@ impl MockArgs {
             self.port, self.scenario
         );
     }
-use clap::{Parser, Subcommand};
+}
 
 /// Developer toolkit for the Stellar fee tracker.
 #[derive(Parser)]
diff --git a/packages/devkit/src/cli/replay.rs b/packages/devkit/src/cli/replay.rs
index ef0cd5e..122b156 100644
--- a/packages/devkit/src/cli/replay.rs
+++ b/packages/devkit/src/cli/replay.rs
@@ -8,6 +8,24 @@ pub struct ReplayArgs {
     pub db: PathBuf,
     /// Show a progress bar during replay.
     pub progress: bool,
+    /// Playback speed multiplier (1.0 = real-time).
+    pub speed: f32,
+    /// Start of the replay window (ISO-8601 timestamp).
+    pub from: Option<String>,
+    /// End of the replay window (ISO-8601 timestamp).
+    pub to: Option<String>,
+}
+
+impl Default for ReplayArgs {
+    fn default() -> Self {
+        Self {
+            db: PathBuf::from("stellar_fees.db"),
+            progress: false,
+            speed: 1.0,
+            from: None,
+            to: None,
+        }
+    }
 }
 
 impl ReplayArgs {
@@ -27,27 +45,10 @@ impl ReplayArgs {
             bar.inc(1);
         }
         bar.finish_with_message("replay complete");
-use clap::Args;
-
-/// Arguments for the `replay` subcommand.
-#[derive(Args)]
-pub struct ReplayArgs {
-    /// Path to the SQLite database file.
-    pub db: PathBuf,
-    /// Playback speed multiplier (1.0 = real-time).
-    #[arg(long, default_value = "1.0")]
-    pub speed: f32,
-    /// Start of the replay window (ISO-8601 timestamp).
-    #[arg(long)]
-    pub from: Option<String>,
-    /// End of the replay window (ISO-8601 timestamp).
-    #[arg(long)]
-    pub to: Option<String>,
-}
+    }
 
-impl ReplayArgs {
     /// Replays fee records filtered by the given time window.
-    pub fn run(&self) {
+    pub fn run_windowed(&self) {
         eprintln!(
             "Replaying from {} at {:.1}x speed, window {:?}..{:?}",
             self.db.display(),
@@ -55,26 +56,10 @@ impl ReplayArgs {
             self.from,
             self.to
         );
-    /// Path to the SQLite database file containing recorded fee data.
-    pub db: PathBuf,
-    /// Playback speed multiplier (1.0 = real-time, 10.0 = 10x faster).
-    #[arg(long, default_value = "1.0")]
-    pub speed: f32,
-}
-
-impl ReplayArgs {
-    /// Replays fee records at the specified speed multiplier.
-    pub fn run(&self) {
-        eprintln!(
-            "Replaying from {} at {:.1}x speed",
-            self.db.display(),
-            self.speed
-        );
-}
+    }
 
-impl ReplayArgs {
     /// Replays fee records from the database to stdout as a JSON stream.
-    pub fn run(&self) {
+    pub fn run_json(&self) {
         eprintln!("Replaying fee records from {}", self.db.display());
         println!("[]");
     }
diff --git a/packages/devkit/src/test_helpers/mod.rs b/packages/devkit/src/test_helpers/mod.rs
index b601a87..cedb970 100644
--- a/packages/devkit/src/test_helpers/mod.rs
+++ b/packages/devkit/src/test_helpers/mod.rs
@@ -1,8 +1,10 @@
-use crate::simulation::fee_model::{FeeModel, FeeModelConfig};
-use crate::types::FeeRecord;
+use crate::simulation::fee_model::{FeeModel, FeeModelConfig, FeePoint};
+
+use rand::rngs::SmallRng;
+use rand::{Rng, SeedableRng};
 
 /// Returns a deterministic fee sequence of `count` records seeded by `seed`.
-pub fn make_fee_sequence(count: usize, seed: u64) -> Vec<FeeRecord> {
+pub fn make_fee_sequence(count: usize, seed: u64) -> Vec<FeePoint> {
     let config = FeeModelConfig {
         seed: Some(seed),
         ..Default::default()
@@ -11,7 +13,7 @@ pub fn make_fee_sequence(count: usize, seed: u64) -> Vec<FeeRecord> {
 }
 
 /// Returns a fee sequence where every record is flagged as a spike.
-pub fn make_spike_sequence(count: usize) -> Vec<FeeRecord> {
+pub fn make_spike_sequence(count: usize) -> Vec<FeePoint> {
     let config = FeeModelConfig {
         spike_probability: 1.0,
         seed: Some(0),
@@ -21,7 +23,7 @@ pub fn make_spike_sequence(count: usize) -> Vec<FeeRecord> {
 }
 
 /// Returns a fee sequence with no spikes (baseline load only).
-pub fn make_baseline_sequence(count: usize) -> Vec<FeeRecord> {
+pub fn make_baseline_sequence(count: usize) -> Vec<FeePoint> {
     let config = FeeModelConfig {
         spike_probability: 0.0,
         seed: Some(1),
@@ -29,10 +31,6 @@ pub fn make_baseline_sequence(count: usize) -> Vec<FeeRecord> {
     };
     FeeModel::new(config).generate(count, 0)
 }
-//! Test helpers: deterministic fee sequence generator and SQLite fixture builder.
-
-use rand::{Rng, SeedableRng};
-use rand::rngs::SmallRng;
 
 /// Generates a deterministic fee sequence from a seed for repeatable tests.
 pub struct FeeGenerator {
@@ -58,21 +56,21 @@ impl FeeGenerator {
 
 /// A simple in-memory fee record for fixture use.
 #[derive(Debug, Clone, PartialEq)]
-pub struct FeeRecord {
+pub struct FixtureFeeRecord {
     pub timestamp: u64,
     pub fee_amount: u64,
     pub ledger_sequence: u64,
     pub tx_hash: String,
 }
 
-/// Builds a vec of FeeRecord fixtures for testing.
+/// Builds a vec of FixtureFeeRecord fixtures for testing.
 pub struct FixtureBuilder;
 
 impl FixtureBuilder {
     /// Build `n` sequential fee records starting at `base_timestamp`.
-    pub fn build(n: usize, base_timestamp: u64, base_fee: u64) -> Vec<FeeRecord> {
+    pub fn build(n: usize, base_timestamp: u64, base_fee: u64) -> Vec<FixtureFeeRecord> {
         (0..n)
-            .map(|i| FeeRecord {
+            .map(|i| FixtureFeeRecord {
                 timestamp: base_timestamp + i as u64,
                 fee_amount: base_fee,
                 ledger_sequence: 1000 + i as u64,
@@ -97,6 +95,9 @@ mod tests {
         let records = FixtureBuilder::build(3, 1000, 100);
         assert_eq!(records[0].timestamp, 1000);
         assert_eq!(records[2].timestamp, 1002);
+    }
+
+    #[test]
     fn same_seed_produces_same_sequence() {
         let a = FeeGenerator::new(42).generate(10, 100, 1000);
         let b = FeeGenerator::new(42).generate(10, 100, 1000);
diff --git a/packages/devkit/tests/harness_integration.rs b/packages/devkit/tests/harness_integration.rs
new file mode 100644
index 0000000..a38bf00
--- /dev/null
+++ b/packages/devkit/tests/harness_integration.rs
@@ -0,0 +1,64 @@
+use std::time::{Duration, Instant};
+
+use stellar_devkit::harness::horizon_mock::HorizonMock;
+
+/// Spin up mock server with normal.json. Assert response status 200 and fee_charged.mode = "100".
+#[test]
+fn normal_scenario_fee_stats_returns_mode_100() {
+    let path = std::path::Path::new("src/harness/scenarios/normal.json");
+    let mock = HorizonMock::new("normal").with_scenario_path(path);
+
+    let body = mock.fee_stats_payload().expect("fee_stats_payload failed");
+    assert!(!body.is_empty(), "response body must not be empty");
+
+    let json: serde_json::Value =
+        serde_json::from_str(&body).expect("response is not valid JSON");
+    let mode = json["fee_stats"]["fee_charged"]["mode"]
+        .as_str()
+        .expect("fee_charged.mode missing");
+    assert_eq!(mode, "100", "expected fee_charged.mode == \"100\", got {}", mode);
+}
+
+/// Spin up with congested.json. Assert fee_charged.p95 parses to a value > 100000.
+#[test]
+fn congested_scenario_fee_stats_p95_exceeds_100k() {
+    let path = std::path::Path::new("src/harness/scenarios/congested.json");
+    let mock = HorizonMock::new("congested").with_scenario_path(path);
+
+    let body = mock.fee_stats_payload().expect("fee_stats_payload failed");
+    let json: serde_json::Value =
+        serde_json::from_str(&body).expect("response is not valid JSON");
+
+    let p95: u64 = json["fee_stats"]["fee_charged"]["p95"]
+        .as_str()
+        .expect("fee_charged.p95 missing")
+        .parse()
+        .expect("fee_charged.p95 is not a number");
+    assert!(p95 > 100_000, "expected p95 > 100000, got {}", p95);
+}
+
+/// Set error_rate=1.0. Assert every request returns 503 (should_inject_error always true).
+#[test]
+fn error_injection_rate_1_always_injects() {
+    let mock = HorizonMock::new("normal").with_error_rate(1.0);
+    for _ in 0..20 {
+        assert!(
+            mock.should_inject_error(),
+            "expected should_inject_error() == true with error_rate=1.0"
+        );
+    }
+}
+
+/// Set delay_ms=200. Assert response time >= 200ms.
+#[test]
+fn response_delay_200ms_respected() {
+    let mock = HorizonMock::new("normal").with_delay_ms(200);
+    let start = Instant::now();
+    mock.apply_delay();
+    let elapsed = start.elapsed();
+    assert!(
+        elapsed >= Duration::from_millis(200),
+        "expected elapsed >= 200ms, got {:?}",
+        elapsed
+    );
+}

From 762194f758d5f6a10ed345cef390e998ff0b7d70 Mon Sep 17 00:00:00 2001
From: temiport25 <temiport25@users.noreply.github.com>
Date: Mon, 1 Jun 2026 11:46:09 +0100
Subject: [PATCH 2/2] fix: apply cargo fmt and rename Window::from_str to parse
 (clippy)

---
 Cargo.lock                                   | 71 ++++++++++++++++++++
 packages/devkit/src/cli/benchmark.rs         | 11 ++-
 packages/devkit/src/cli/export.rs            | 25 +++++--
 packages/devkit/src/test_helpers/mod.rs      |  8 ++-
 packages/devkit/tests/cli_export.rs          | 15 ++++-
 packages/devkit/tests/cli_replay.rs          | 10 ++-
 packages/devkit/tests/harness_integration.rs | 12 ++--
 packages/devkit/tests/percentile_prop.rs     |  4 +-
 packages/devkit/tests/spike_prop.rs          |  4 +-
 9 files changed, 136 insertions(+), 24 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 856e6de..f6b972d 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -402,6 +402,19 @@ dependencies = [
  "crossbeam-utils",
 ]
 
+[[package]]
+name = "console"
+version = "0.15.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "054ccb5b10f9f2cbf51eb355ca1d05c2d279ce1804688d0db74b4733a5aeafd8"
+dependencies = [
+ "encode_unicode",
+ "libc",
+ "once_cell",
+ "unicode-width",
+ "windows-sys 0.59.0",
+]
+
 [[package]]
 name = "const-oid"
 version = "0.9.6"
@@ -616,6 +629,12 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "encode_unicode"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34aa73646ffb006b8f5147f3dc182bd4bcb190227ce861fc4a4844bf8e3cb2c0"
+
 [[package]]
 name = "encoding_rs"
 version = "0.8.35"
@@ -1292,6 +1311,19 @@ dependencies = [
  "hashbrown 0.16.1",
 ]
 
+[[package]]
+name = "indicatif"
+version = "0.17.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "183b3088984b400f4cfac3620d5e076c84da5364016b4f49473de574b2586235"
+dependencies = [
+ "console",
+ "number_prefix",
+ "portable-atomic",
+ "unicode-width",
+ "web-time",
+]
+
 [[package]]
 name = "infer"
 version = "0.2.3"
@@ -1571,6 +1603,12 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "number_prefix"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "830b246a0e5f20af87141b25c173cd1b609bd7779a4617d6ec582abaf90870f3"
+
 [[package]]
 name = "once_cell"
 version = "1.21.3"
@@ -1750,6 +1788,12 @@ dependencies = [
  "plotters-backend",
 ]
 
+[[package]]
+name = "portable-atomic"
+version = "1.13.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c33a9471896f1c69cecef8d20cbe2f7accd12527ce60845ff44c153bb2a21b49"
+
 [[package]]
 name = "potential_utf"
 version = "0.1.4"
@@ -2573,7 +2617,9 @@ name = "stellar-devkit"
 version = "0.1.0"
 dependencies = [
  "axum",
+ "clap",
  "criterion",
+ "indicatif",
  "rand 0.8.5",
  "serde",
  "serde_json",
@@ -3006,6 +3052,12 @@ version = "1.12.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f6ccf251212114b54433ec949fd6a7841275f9ada20dddd2f29e9ceea4501493"
 
+[[package]]
+name = "unicode-width"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b4ac048d71ede7ee76d585517add45da530660ef4390e49b098733c6e897f254"
+
 [[package]]
 name = "unicode_categories"
 version = "0.1.1"
@@ -3191,6 +3243,16 @@ dependencies = [
  "wasm-bindgen",
 ]
 
+[[package]]
+name = "web-time"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5a6580f308b1fad9207618087a65c04e7a10bc77e02c8e84e9b00dd4b12fa0bb"
+dependencies = [
+ "js-sys",
+ "wasm-bindgen",
+]
+
 [[package]]
 name = "whoami"
 version = "1.6.1"
@@ -3287,6 +3349,15 @@ dependencies = [
  "windows-targets 0.52.6",
 ]
 
+[[package]]
+name = "windows-sys"
+version = "0.59.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e38bc4d79ed67fd075bcc251a1c39b32a1776bbe92e5bef1f0bf1f8c531853b"
+dependencies = [
+ "windows-targets 0.52.6",
+]
+
 [[package]]
 name = "windows-sys"
 version = "0.60.2"
diff --git a/packages/devkit/src/cli/benchmark.rs b/packages/devkit/src/cli/benchmark.rs
index 52cb660..67db741 100644
--- a/packages/devkit/src/cli/benchmark.rs
+++ b/packages/devkit/src/cli/benchmark.rs
@@ -1,4 +1,4 @@
-/// Runs benchmarks against the fee tracker pipeline.
+/// Runs benchmarks against the fee tracker pipeline.
 pub struct Benchmark;
 
 impl Benchmark {
@@ -27,7 +27,12 @@ impl Benchmark {
     /// Run all analysis benchmarks and print a summary table.
     pub fn run_all(fees: &[f64], window: usize, alpha: f64) {
         println!("=== Benchmark Results ===");
-        println!("Input: {} data points, window={}, alpha={}", fees.len(), window, alpha);
+        println!(
+            "Input: {} data points, window={}, alpha={}",
+            fees.len(),
+            window,
+            alpha
+        );
         println!();
         Self::compare_spike(fees, window, alpha);
     }
@@ -42,4 +47,4 @@ mod tests {
         let fees: Vec<f64> = (1..=10).map(|x| x as f64 * 100.0).collect();
         Benchmark::run_all(&fees, 3, 0.3);
     }
-}
\ No newline at end of file
+}
diff --git a/packages/devkit/src/cli/export.rs b/packages/devkit/src/cli/export.rs
index 4202a2c..8052ad7 100644
--- a/packages/devkit/src/cli/export.rs
+++ b/packages/devkit/src/cli/export.rs
@@ -30,7 +30,7 @@ pub enum Window {
 }
 
 impl Window {
-    pub fn from_str(s: &str) -> Option<Self> {
+    pub fn parse(s: &str) -> Option<Self> {
         match s {
             "1h" => Some(Self::OneHour),
             "6h" => Some(Self::SixHours),
@@ -55,7 +55,7 @@ pub struct Export;
 
 impl Export {
     /// Filter points by window relative to the latest timestamp.
-    pub fn filter_window<'a>(points: &'a [FeePoint], window: Window) -> &'a [FeePoint] {
+    pub fn filter_window(points: &[FeePoint], window: Window) -> &[FeePoint] {
         match window.cutoff_seconds() {
             None => points,
             Some(secs) => {
@@ -108,13 +108,28 @@ mod tests {
 
     fn pts() -> Vec<FeePoint> {
         vec![
-            FeePoint { timestamp: 0, fee: 100, ledger: 1, is_spike: false },
-            FeePoint { timestamp: 7200, fee: 200, ledger: 2, is_spike: true },
+            FeePoint {
+                timestamp: 0,
+                fee: 100,
+                ledger: 1,
+                is_spike: false,
+            },
+            FeePoint {
+                timestamp: 7200,
+                fee: 200,
+                ledger: 2,
+                is_spike: true,
+            },
         ]
     }
 
     fn sample() -> Vec<FeePoint> {
-        vec![FeePoint { timestamp: 1000, fee: 100, ledger: 1, is_spike: false }]
+        vec![FeePoint {
+            timestamp: 1000,
+            fee: 100,
+            ledger: 1,
+            is_spike: false,
+        }]
     }
 
     #[test]
diff --git a/packages/devkit/src/test_helpers/mod.rs b/packages/devkit/src/test_helpers/mod.rs
index cedb970..cd3c835 100644
--- a/packages/devkit/src/test_helpers/mod.rs
+++ b/packages/devkit/src/test_helpers/mod.rs
@@ -40,12 +40,16 @@ pub struct FeeGenerator {
 impl FeeGenerator {
     /// Create a generator with the given seed.
     pub fn new(seed: u64) -> Self {
-        Self { rng: SmallRng::seed_from_u64(seed) }
+        Self {
+            rng: SmallRng::seed_from_u64(seed),
+        }
     }
 
     /// Generate `n` fee values in the range [min_fee, max_fee].
     pub fn generate(&mut self, n: usize, min_fee: u64, max_fee: u64) -> Vec<u64> {
-        (0..n).map(|_| self.rng.gen_range(min_fee..=max_fee)).collect()
+        (0..n)
+            .map(|_| self.rng.gen_range(min_fee..=max_fee))
+            .collect()
     }
 
     /// Generate a flat sequence of `n` identical fees (useful for baseline tests).
diff --git a/packages/devkit/tests/cli_export.rs b/packages/devkit/tests/cli_export.rs
index 4b10b94..22c8c6b 100644
--- a/packages/devkit/tests/cli_export.rs
+++ b/packages/devkit/tests/cli_export.rs
@@ -3,7 +3,10 @@ use stellar_devkit::simulation::fee_model::{FeeModel, FeeModelConfig};
 
 #[test]
 fn export_csv_has_correct_header() {
-    let config = FeeModelConfig { seed: Some(1), ..Default::default() };
+    let config = FeeModelConfig {
+        seed: Some(1),
+        ..Default::default()
+    };
     let mut model = FeeModel::new(config);
     let points = model.generate(5, 0);
     let csv = Export::to_csv(&points);
@@ -15,7 +18,10 @@ fn export_csv_has_correct_header() {
 
 #[test]
 fn export_csv_row_count_matches_input() {
-    let config = FeeModelConfig { seed: Some(2), ..Default::default() };
+    let config = FeeModelConfig {
+        seed: Some(2),
+        ..Default::default()
+    };
     let mut model = FeeModel::new(config);
     let points = model.generate(10, 0);
     let csv = Export::to_csv(&points);
@@ -30,7 +36,10 @@ fn export_csv_row_count_matches_input() {
 
 #[test]
 fn export_csv_columns_are_parseable() {
-    let config = FeeModelConfig { seed: Some(3), ..Default::default() };
+    let config = FeeModelConfig {
+        seed: Some(3),
+        ..Default::default()
+    };
     let mut model = FeeModel::new(config);
     let points = model.generate(1, 1_000);
     let csv = Export::to_csv(&points);
diff --git a/packages/devkit/tests/cli_replay.rs b/packages/devkit/tests/cli_replay.rs
index efa1599..17a57df 100644
--- a/packages/devkit/tests/cli_replay.rs
+++ b/packages/devkit/tests/cli_replay.rs
@@ -2,7 +2,10 @@ use stellar_devkit::simulation::fee_model::{FeeModel, FeeModelConfig};
 
 #[test]
 fn replay_generates_expected_record_count() {
-    let config = FeeModelConfig { seed: Some(42), ..Default::default() };
+    let config = FeeModelConfig {
+        seed: Some(42),
+        ..Default::default()
+    };
     let mut model = FeeModel::new(config);
     let records = model.generate(100, 0);
     assert_eq!(
@@ -35,7 +38,10 @@ fn replay_records_have_sequential_timestamps() {
 #[test]
 fn replay_is_deterministic_with_same_seed() {
     let make = || {
-        let cfg = FeeModelConfig { seed: Some(77), ..Default::default() };
+        let cfg = FeeModelConfig {
+            seed: Some(77),
+            ..Default::default()
+        };
         FeeModel::new(cfg).generate(100, 0)
     };
     let a = make();
diff --git a/packages/devkit/tests/harness_integration.rs b/packages/devkit/tests/harness_integration.rs
index a38bf00..5e90f1d 100644
--- a/packages/devkit/tests/harness_integration.rs
+++ b/packages/devkit/tests/harness_integration.rs
@@ -11,12 +11,15 @@ fn normal_scenario_fee_stats_returns_mode_100() {
     let body = mock.fee_stats_payload().expect("fee_stats_payload failed");
     assert!(!body.is_empty(), "response body must not be empty");
 
-    let json: serde_json::Value =
-        serde_json::from_str(&body).expect("response is not valid JSON");
+    let json: serde_json::Value = serde_json::from_str(&body).expect("response is not valid JSON");
     let mode = json["fee_stats"]["fee_charged"]["mode"]
         .as_str()
         .expect("fee_charged.mode missing");
-    assert_eq!(mode, "100", "expected fee_charged.mode == \"100\", got {}", mode);
+    assert_eq!(
+        mode, "100",
+        "expected fee_charged.mode == \"100\", got {}",
+        mode
+    );
 }
 
 /// Spin up with congested.json. Assert fee_charged.p95 parses to a value > 100000.
@@ -26,8 +29,7 @@ fn congested_scenario_fee_stats_p95_exceeds_100k() {
     let mock = HorizonMock::new("congested").with_scenario_path(path);
 
     let body = mock.fee_stats_payload().expect("fee_stats_payload failed");
-    let json: serde_json::Value =
-        serde_json::from_str(&body).expect("response is not valid JSON");
+    let json: serde_json::Value = serde_json::from_str(&body).expect("response is not valid JSON");
 
     let p95: u64 = json["fee_stats"]["fee_charged"]["p95"]
         .as_str()
diff --git a/packages/devkit/tests/percentile_prop.rs b/packages/devkit/tests/percentile_prop.rs
index 83e981d..bb50a4a 100644
--- a/packages/devkit/tests/percentile_prop.rs
+++ b/packages/devkit/tests/percentile_prop.rs
@@ -1,4 +1,4 @@
-//! Property-style tests for percentile functions.
+//! Property-style tests for percentile functions.
 //! Verifies invariants on arbitrary fee sequences without external proptest crate.
 
 use stellar_devkit::analysis::percentile::Percentile;
@@ -49,4 +49,4 @@ fn interpolation_p50_of_two_elements_is_midpoint() {
         let mid = Percentile::linear_interpolation(&data, 50);
         assert_eq!(mid, (a + b) / 2);
     }
-}
\ No newline at end of file
+}
diff --git a/packages/devkit/tests/spike_prop.rs b/packages/devkit/tests/spike_prop.rs
index 7d306c3..494b9b2 100644
--- a/packages/devkit/tests/spike_prop.rs
+++ b/packages/devkit/tests/spike_prop.rs
@@ -1,4 +1,4 @@
-//! Property-style tests for spike classifier — no false positives on flat sequences.
+//! Property-style tests for spike classifier — no false positives on flat sequences.
 
 use stellar_devkit::analysis::spike_classifier::SpikeClassifier;
 
@@ -45,4 +45,4 @@ fn spike_detected_when_fee_exceeds_threshold() {
     let fees = vec![100u64, 200, 100];
     let events = SpikeClassifier::detect(&fees, 100);
     assert!(!events.is_empty());
-}
\ No newline at end of file
+}