implement watch mode

- add `--watch` flag - start saving seeds in persistent storage - make a separate version of execution functions that use `vector of interaction` instead of `InteractionPlan`
2026-02-23 17:05:36 +01:00 · 2025-01-18 23:54:03 +03:00
parent c30e2757b4
commit e476b9f697
12 changed files with 521 additions and 91 deletions
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -183,9 +183,9 @@ checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"

 [[package]]
 name = "bitflags"
-version = "2.6.0"
+version = "2.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b048fb63fd8b5923fc5aa7b340d8e156aec7ec02f0c78fa8a6ddc2613f6f71de"
+checksum = "8f68f53c83ab957f72c32642f3868eec03eb974d1fb82e453128456482613d36"

 [[package]]
 name = "block-buffer"
@@ -735,6 +735,18 @@ dependencies = [
 "windows-sys 0.48.0",
 ]

+[[package]]
+name = "filetime"
+version = "0.2.25"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "35c0522e981e68cbfa8c3f978441a5f34b30b96e146b33cd3359176b50fe8586"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "libredox",
+ "windows-sys 0.59.0",
+]
+
 [[package]]
 name = "findshlibs"
 version = "0.10.2"
@@ -753,6 +765,15 @@ version = "2.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6c2141d6d6c8512188a7891b4b01590a45f6dac67afb4f255c4124dbb86d4eaa"

+[[package]]
+name = "fsevent-sys"
+version = "4.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "76ee7a02da4d231650c7cea31349b889be2f45ddb3ef3032d2ec8185f6313fd2"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "futures"
 version = "0.3.31"
@@ -1009,6 +1030,26 @@ dependencies = [
 "str_stack",
 ]

+[[package]]
+name = "inotify"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f37dccff2791ab604f9babef0ba14fbe0be30bd368dc541e2b08d07c8aa908f3"
+dependencies = [
+ "bitflags 2.8.0",
+ "inotify-sys",
+ "libc",
+]
+
+[[package]]
+name = "inotify-sys"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e05c02b5e89bff3b946cedeca278abc628fe811e604f027c45a8aa3cf793d0eb"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "io-uring"
 version = "0.6.4"
@@ -1125,6 +1166,26 @@ dependencies = [
 "chrono",
 ]

+[[package]]
+name = "kqueue"
+version = "1.0.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7447f1ca1b7b563588a205fe93dea8df60fd981423a768bc1c0ded35ed147d0c"
+dependencies = [
+ "kqueue-sys",
+ "libc",
+]
+
+[[package]]
+name = "kqueue-sys"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ed9625ffda8729b85e45cf04090035ac368927b8cebc34898e7c120f52e4838b"
+dependencies = [
+ "bitflags 1.3.2",
+ "libc",
+]
+
 [[package]]
 name = "lazy_static"
 version = "1.5.0"
@@ -1163,8 +1224,9 @@ version = "0.1.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c0ff37bd590ca25063e35af745c343cb7a0271906fb7b37e4813e8f79f00268d"
 dependencies = [
- "bitflags 2.6.0",
+ "bitflags 2.8.0",
 "libc",
+ "redox_syscall",
 ]

 [[package]]
@@ -1282,6 +1344,7 @@ dependencies = [
 "env_logger 0.10.2",
 "limbo_core",
 "log",
+ "notify",
 "rand",
 "rand_chacha",
 "serde",
@@ -1416,6 +1479,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2886843bf800fba2e3377cff24abf6379b4c4d5c6681eaf9ea5b0d15090450bd"
 dependencies = [
 "libc",
+ "log",
 "wasi",
 "windows-sys 0.52.0",
 ]
@@ -1472,7 +1536,7 @@ version = "0.29.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "71e2746dc3a24dd78b3cfcb7be93368c6de9963d30f43a6a73998a9cf4b17b46"
 dependencies = [
- "bitflags 2.6.0",
+ "bitflags 2.8.0",
 "cfg-if",
 "cfg_aliases",
 "libc",
@@ -1488,6 +1552,31 @@ dependencies = [
 "minimal-lexical",
 ]

+[[package]]
+name = "notify"
+version = "8.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2fee8403b3d66ac7b26aee6e40a897d85dc5ce26f44da36b8b73e987cc52e943"
+dependencies = [
+ "bitflags 2.8.0",
+ "filetime",
+ "fsevent-sys",
+ "inotify",
+ "kqueue",
+ "libc",
+ "log",
+ "mio",
+ "notify-types",
+ "walkdir",
+ "windows-sys 0.59.0",
+]
+
+[[package]]
+name = "notify-types"
+version = "2.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5e0826a989adedc2a244799e823aece04662b66609d96af8dff7ac6df9a8925d"
+
 [[package]]
 name = "num-format"
 version = "0.4.4"
@@ -1949,7 +2038,7 @@ version = "0.5.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9b6dfecf2c74bce2466cabf93f6664d6998a69eb21e39f4207930065b27b771f"
 dependencies = [
- "bitflags 2.6.0",
+ "bitflags 2.8.0",
 ]

 [[package]]
@@ -2042,7 +2131,7 @@ version = "0.29.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "549b9d036d571d42e6e85d1c1425e2ac83491075078ca9a15be021c56b1641f2"
 dependencies = [
- "bitflags 2.6.0",
+ "bitflags 2.8.0",
 "fallible-iterator 0.2.0",
 "fallible-streaming-iterator",
 "hashlink",
@@ -2071,7 +2160,7 @@ version = "0.38.42"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f93dc38ecbab2eb790ff964bb77fa94faf256fd3e73285fd7ba0903b76bedb85"
 dependencies = [
- "bitflags 2.6.0",
+ "bitflags 2.8.0",
 "errno",
 "libc",
 "linux-raw-sys",
@@ -2084,7 +2173,7 @@ version = "12.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "994eca4bca05c87e86e15d90fc7a91d1be64b4482b38cb2d27474568fe7c9db9"
 dependencies = [
- "bitflags 2.6.0",
+ "bitflags 2.8.0",
 "cfg-if",
 "clipboard-win",
 "fd-lock",
@@ -2228,7 +2317,7 @@ dependencies = [
 name = "sqlite3-parser"
 version = "0.13.0"
 dependencies = [
- "bitflags 2.6.0",
+ "bitflags 2.8.0",
 "cc",
 "env_logger 0.11.5",
 "fallible-iterator 0.3.0",
--- a/simulator/Cargo.toml
+++ b/simulator/Cargo.toml
@@ -25,3 +25,4 @@ anarchist-readable-name-generator-lib = "0.1.2"
 clap = { version = "4.5", features = ["derive"] }
 serde = { version = "1.0", features = ["derive"] }
 serde_json = { version = "1.0" }
+notify = "8.0.0"
--- a/simulator/generation/plan.rs
+++ b/simulator/generation/plan.rs
@@ -1,4 +1,4 @@
-use std::{fmt::Display, rc::Rc, vec};
+use std::{fmt::Display, path::Path, rc::Rc, vec};

 use limbo_core::{Connection, Result, StepResult};
 use serde::{Deserialize, Serialize};
@@ -26,6 +26,69 @@ pub(crate) struct InteractionPlan {
    pub(crate) plan: Vec<Interactions>,
 }

+impl InteractionPlan {
+    /// Compute via diff computes a a plan from a given `.plan` file without the need to parse
+    /// sql. This is possible because there are two versions of the plan file, one that is human
+    /// readable and one that is serialized as JSON. Under watch mode, the users will be able to
+    /// delete interactions from the human readable file, and this function uses the JSON file as
+    /// a baseline to detect with interactions were deleted and constructs the plan from the
+    /// remaining interactions.
+    pub(crate) fn compute_via_diff(plan_path: &Path) -> Vec<Vec<Interaction>> {
+        let interactions = std::fs::read_to_string(plan_path).unwrap();
+        let interactions = interactions.lines().collect::<Vec<_>>();
+
+        let plan: InteractionPlan = serde_json::from_str(
+            std::fs::read_to_string(plan_path.with_extension("plan.json"))
+                .unwrap()
+                .as_str(),
+        )
+        .unwrap();
+
+        let mut plan = plan
+            .plan
+            .into_iter()
+            .map(|i| i.interactions())
+            .collect::<Vec<_>>();
+
+        let (mut i, mut j1, mut j2) = (0, 0, 0);
+
+        while i < interactions.len() && j1 < plan.len() {
+            if interactions[i].starts_with("-- begin")
+                || interactions[i].starts_with("-- end")
+                || interactions[i].is_empty()
+            {
+                i += 1;
+                continue;
+            }
+
+            if interactions[i].contains(plan[j1][j2].to_string().as_str()) {
+                i += 1;
+                if j2 + 1 < plan[j1].len() {
+                    j2 += 1;
+                } else {
+                    j1 += 1;
+                    j2 = 0;
+                }
+            } else {
+                plan[j1].remove(j2);
+
+                if plan[j1].is_empty() {
+                    plan.remove(j1);
+                    j2 = 0;
+                }
+            }
+        }
+        if j1 < plan.len() {
+            if j2 < plan[j1].len() {
+                let _ = plan[j1].split_off(j2);
+            }
+            let _ = plan.split_off(j1);
+        }
+
+        plan
+    }
+}
+
 pub(crate) struct InteractionPlanState {
    pub(crate) stack: Vec<ResultSet>,
    pub(crate) interaction_pointer: usize,
@@ -110,12 +173,12 @@ impl Display for InteractionPlan {
                        match interaction {
                            Interaction::Query(query) => writeln!(f, "{};", query)?,
                            Interaction::Assumption(assumption) => {
-                                writeln!(f, "-- ASSUME: {};", assumption.message)?
+                                writeln!(f, "-- ASSUME {};", assumption.message)?
                            }
                            Interaction::Assertion(assertion) => {
-                                writeln!(f, "-- ASSERT: {};", assertion.message)?
+                                writeln!(f, "-- ASSERT {};", assertion.message)?
                            }
-                            Interaction::Fault(fault) => writeln!(f, "-- FAULT: {};", fault)?,
+                            Interaction::Fault(fault) => writeln!(f, "-- FAULT '{}';", fault)?,
                        }
                    }
                    writeln!(f, "-- end testing '{}'", name)?;
@@ -162,9 +225,9 @@ impl Display for Interaction {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Self::Query(query) => write!(f, "{}", query),
-            Self::Assumption(assumption) => write!(f, "ASSUME: {}", assumption.message),
-            Self::Assertion(assertion) => write!(f, "ASSERT: {}", assertion.message),
-            Self::Fault(fault) => write!(f, "FAULT: {}", fault),
+            Self::Assumption(assumption) => write!(f, "ASSUME {}", assumption.message),
+            Self::Assertion(assertion) => write!(f, "ASSERT {}", assertion.message),
+            Self::Fault(fault) => write!(f, "FAULT '{}'", fault),
        }
    }
 }
@@ -326,6 +389,14 @@ impl ArbitraryFrom<&mut SimulatorEnv> for InteractionPlan {
 }

 impl Interaction {
+    pub(crate) fn shadow(&self, env: &mut SimulatorEnv) {
+        match self {
+            Self::Query(query) => query.shadow(env),
+            Self::Assumption(_) => {}
+            Self::Assertion(_) => {}
+            Self::Fault(_) => {}
+        }
+    }
    pub(crate) fn execute_query(&self, conn: &mut Rc<Connection>) -> ResultSet {
        if let Self::Query(query) = self {
            let query_str = query.to_string();
--- a/simulator/generation/property.rs
+++ b/simulator/generation/property.rs
@@ -104,7 +104,6 @@ impl Property {

                let assertion = Interaction::Assertion(Assertion {
                    message: format!(
-                        // todo: add the part inserting ({} = {})",
                        "row [{:?}] not found in table {}",
                        row.iter().map(|v| v.to_string()).collect::<Vec<String>>(),
                        insert.table,
--- a/simulator/main.rs
+++ b/simulator/main.rs
@@ -1,17 +1,20 @@
 #![allow(clippy::arc_with_non_send_sync, dead_code)]
 use clap::Parser;
-use generation::plan::{InteractionPlan, InteractionPlanState};
+use generation::plan::{Interaction, InteractionPlan, InteractionPlanState};
 use generation::ArbitraryFrom;
 use limbo_core::Database;
+use notify::event::{DataChange, ModifyKind};
+use notify::{EventKind, RecursiveMode, Watcher};
 use rand::prelude::*;
 use runner::cli::SimulatorCLI;
 use runner::env::SimulatorEnv;
 use runner::execution::{execute_plans, Execution, ExecutionHistory, ExecutionResult};
+use runner::watch;
 use std::any::Any;
 use std::backtrace::Backtrace;
 use std::io::Write;
 use std::path::{Path, PathBuf};
-use std::sync::{Arc, Mutex};
+use std::sync::{mpsc, Arc, Mutex};
 use tempfile::TempDir;

 mod generation;
@@ -46,6 +49,10 @@ impl Paths {
            log::info!("shrunk database path: {:?}", paths.shrunk_db);
        }
        log::info!("simulator plan path: {:?}", paths.plan);
+        log::info!(
+            "simulator plan serialized path: {:?}",
+            paths.plan.with_extension("plan.json")
+        );
        if shrink {
            log::info!("shrunk plan path: {:?}", paths.shrunk_plan);
        }
@@ -77,7 +84,85 @@ fn main() -> Result<(), String> {
    log::info!("seed: {}", seed);

    let last_execution = Arc::new(Mutex::new(Execution::new(0, 0, 0)));
+    let (env, plans) = setup_simulation(seed, &cli_opts, &paths.db, &paths.plan);

+    if cli_opts.watch {
+        watch_mode(seed, &cli_opts, &paths, last_execution.clone()).unwrap();
+    } else {
+        run_simulator(seed, &cli_opts, &paths, env, plans, last_execution.clone());
+    }
+
+    Ok(())
+}
+
+fn watch_mode(
+    seed: u64,
+    cli_opts: &SimulatorCLI,
+    paths: &Paths,
+    last_execution: Arc<Mutex<Execution>>,
+) -> notify::Result<()> {
+    let (tx, rx) = mpsc::channel::<notify::Result<notify::Event>>();
+    println!("watching {:?}", paths.plan);
+    // Use recommended_watcher() to automatically select the best implementation
+    // for your platform. The `EventHandler` passed to this constructor can be a
+    // closure, a `std::sync::mpsc::Sender`, a `crossbeam_channel::Sender`, or
+    // another type the trait is implemented for.
+    let mut watcher = notify::recommended_watcher(tx)?;
+
+    // Add a path to be watched. All files and directories at that path and
+    // below will be monitored for changes.
+    watcher.watch(&paths.plan, RecursiveMode::NonRecursive)?;
+    // Block forever, printing out events as they come in
+    for res in rx {
+        match res {
+            Ok(event) => {
+                if let EventKind::Modify(ModifyKind::Data(DataChange::Content)) = event.kind {
+                    log::info!("plan file modified, rerunning simulation");
+
+                    let result = SandboxedResult::from(
+                        std::panic::catch_unwind(|| {
+                            let plan: Vec<Vec<Interaction>> =
+                                InteractionPlan::compute_via_diff(&paths.plan);
+
+                            let mut env = SimulatorEnv::new(seed, cli_opts, &paths.db);
+                            plan.iter().for_each(|is| {
+                                is.iter().for_each(|i| {
+                                    i.shadow(&mut env);
+                                });
+                            });
+                            let env = Arc::new(Mutex::new(env.clone()));
+                            watch::run_simulation(env, &mut [plan], last_execution.clone())
+                        }),
+                        last_execution.clone(),
+                    );
+                    match result {
+                        SandboxedResult::Correct => {
+                            log::info!("simulation succeeded");
+                            println!("simulation succeeded");
+                        }
+                        SandboxedResult::Panicked { error, .. }
+                        | SandboxedResult::FoundBug { error, .. } => {
+                            log::error!("simulation failed: '{}'", error);
+                            println!("simulation failed: '{}'", error);
+                        }
+                    }
+                }
+            }
+            Err(e) => println!("watch error: {:?}", e),
+        }
+    }
+
+    Ok(())
+}
+
+fn run_simulator(
+    seed: u64,
+    cli_opts: &SimulatorCLI,
+    paths: &Paths,
+    env: SimulatorEnv,
+    plans: Vec<InteractionPlan>,
+    last_execution: Arc<Mutex<Execution>>,
+) {
    std::panic::set_hook(Box::new(move |info| {
        log::error!("panic occurred");

@@ -94,8 +179,6 @@ fn main() -> Result<(), String> {
        log::error!("captured backtrace:\n{}", bt);
    }));

-    let (env, plans) = setup_simulation(seed, &cli_opts, &paths.db, &paths.plan);
-
    let env = Arc::new(Mutex::new(env));
    let result = SandboxedResult::from(
        std::panic::catch_unwind(|| {
@@ -105,65 +188,13 @@ fn main() -> Result<(), String> {
    );

    if cli_opts.doublecheck {
-        {
-            let mut env_ = env.lock().unwrap();
-            env_.db = Database::open_file(env_.io.clone(), paths.doublecheck_db.to_str().unwrap())
-                .unwrap();
-        }
-
-        // Run the simulation again
-        let result2 = SandboxedResult::from(
-            std::panic::catch_unwind(|| {
-                run_simulation(env.clone(), &mut plans.clone(), last_execution.clone())
-            }),
-            last_execution.clone(),
-        );
-
-        match (result, result2) {
-            (SandboxedResult::Correct, SandboxedResult::Panicked { .. }) => {
-                log::error!("doublecheck failed! first run succeeded, but second run panicked.");
-            }
-            (SandboxedResult::FoundBug { .. }, SandboxedResult::Panicked { .. }) => {
-                log::error!(
-                    "doublecheck failed! first run failed an assertion, but second run panicked."
-                );
-            }
-            (SandboxedResult::Panicked { .. }, SandboxedResult::Correct) => {
-                log::error!("doublecheck failed! first run panicked, but second run succeeded.");
-            }
-            (SandboxedResult::Panicked { .. }, SandboxedResult::FoundBug { .. }) => {
-                log::error!(
-                    "doublecheck failed! first run panicked, but second run failed an assertion."
-                );
-            }
-            (SandboxedResult::Correct, SandboxedResult::FoundBug { .. }) => {
-                log::error!(
-                    "doublecheck failed! first run succeeded, but second run failed an assertion."
-                );
-            }
-            (SandboxedResult::FoundBug { .. }, SandboxedResult::Correct) => {
-                log::error!(
-                    "doublecheck failed! first run failed an assertion, but second run succeeded."
-                );
-            }
-            (SandboxedResult::Correct, SandboxedResult::Correct)
-            | (SandboxedResult::FoundBug { .. }, SandboxedResult::FoundBug { .. })
-            | (SandboxedResult::Panicked { .. }, SandboxedResult::Panicked { .. }) => {
-                // Compare the two database files byte by byte
-                let db_bytes = std::fs::read(&paths.db).unwrap();
-                let doublecheck_db_bytes = std::fs::read(&paths.doublecheck_db).unwrap();
-                if db_bytes != doublecheck_db_bytes {
-                    log::error!("doublecheck failed! database files are different.");
-                } else {
-                    log::info!("doublecheck succeeded! database files are the same.");
-                }
-            }
-        }
+        doublecheck(env.clone(), paths, &plans, last_execution.clone(), result);
    } else {
        // No doublecheck, run shrinking if panicking or found a bug.
        match &result {
            SandboxedResult::Correct => {
                log::info!("simulation succeeded");
+                println!("simulation succeeded");
            }
            SandboxedResult::Panicked {
                error,
@@ -191,6 +222,7 @@ fn main() -> Result<(), String> {
                }

                log::error!("simulation failed: '{}'", error);
+                println!("simulation failed: '{}'", error);

                if cli_opts.shrink {
                    log::info!("Starting to shrink");
@@ -268,8 +300,69 @@ fn main() -> Result<(), String> {
    }
    println!("simulator history path: {:?}", paths.history);
    println!("seed: {}", seed);
+}

-    Ok(())
+fn doublecheck(
+    env: Arc<Mutex<SimulatorEnv>>,
+    paths: &Paths,
+    plans: &[InteractionPlan],
+    last_execution: Arc<Mutex<Execution>>,
+    result: SandboxedResult,
+) {
+    {
+        let mut env_ = env.lock().unwrap();
+        env_.db =
+            Database::open_file(env_.io.clone(), paths.doublecheck_db.to_str().unwrap()).unwrap();
+    }
+
+    // Run the simulation again
+    let result2 = SandboxedResult::from(
+        std::panic::catch_unwind(|| {
+            run_simulation(env.clone(), &mut plans.to_owned(), last_execution.clone())
+        }),
+        last_execution.clone(),
+    );
+
+    match (result, result2) {
+        (SandboxedResult::Correct, SandboxedResult::Panicked { .. }) => {
+            log::error!("doublecheck failed! first run succeeded, but second run panicked.");
+        }
+        (SandboxedResult::FoundBug { .. }, SandboxedResult::Panicked { .. }) => {
+            log::error!(
+                "doublecheck failed! first run failed an assertion, but second run panicked."
+            );
+        }
+        (SandboxedResult::Panicked { .. }, SandboxedResult::Correct) => {
+            log::error!("doublecheck failed! first run panicked, but second run succeeded.");
+        }
+        (SandboxedResult::Panicked { .. }, SandboxedResult::FoundBug { .. }) => {
+            log::error!(
+                "doublecheck failed! first run panicked, but second run failed an assertion."
+            );
+        }
+        (SandboxedResult::Correct, SandboxedResult::FoundBug { .. }) => {
+            log::error!(
+                "doublecheck failed! first run succeeded, but second run failed an assertion."
+            );
+        }
+        (SandboxedResult::FoundBug { .. }, SandboxedResult::Correct) => {
+            log::error!(
+                "doublecheck failed! first run failed an assertion, but second run succeeded."
+            );
+        }
+        (SandboxedResult::Correct, SandboxedResult::Correct)
+        | (SandboxedResult::FoundBug { .. }, SandboxedResult::FoundBug { .. })
+        | (SandboxedResult::Panicked { .. }, SandboxedResult::Panicked { .. }) => {
+            // Compare the two database files byte by byte
+            let db_bytes = std::fs::read(&paths.db).unwrap();
+            let doublecheck_db_bytes = std::fs::read(&paths.doublecheck_db).unwrap();
+            if db_bytes != doublecheck_db_bytes {
+                log::error!("doublecheck failed! database files are different.");
+            } else {
+                log::info!("doublecheck succeeded! database files are the same.");
+            }
+        }
+    }
 }

 #[derive(Debug)]
@@ -326,11 +419,17 @@ impl SandboxedResult {
 }

 fn setup_simulation(
-    seed: u64,
+    mut seed: u64,
    cli_opts: &SimulatorCLI,
    db_path: &Path,
    plan_path: &Path,
 ) -> (SimulatorEnv, Vec<InteractionPlan>) {
+    if let Some(load) = &cli_opts.load {
+        let seed_path = PathBuf::from(load).with_extension("seed");
+        let seed_str = std::fs::read_to_string(&seed_path).unwrap();
+        seed = seed_str.parse().unwrap();
+    }
+
    let mut env = SimulatorEnv::new(seed, cli_opts, db_path);

    // todo: the loading works correctly because of a hacky decision
@@ -357,14 +456,16 @@ fn setup_simulation(
    // todo: create a detailed plan file with all the plans. for now, we only use 1 connection, so it's safe to use the first plan.
    f.write_all(plan.to_string().as_bytes()).unwrap();

-    let json_path = plan_path.with_extension("plan.json");
-    let mut f = std::fs::File::create(&json_path).unwrap();
+    let serialized_plan_path = plan_path.with_extension("plan.json");
+    let mut f = std::fs::File::create(&serialized_plan_path).unwrap();
    f.write_all(serde_json::to_string(&plan).unwrap().as_bytes())
        .unwrap();

-    log::info!("{}", plan.stats());
+    let seed_path = plan_path.with_extension("seed");
+    let mut f = std::fs::File::create(&seed_path).unwrap();
+    f.write_all(seed.to_string().as_bytes()).unwrap();

-    log::info!("Executing database interaction plan...");
+    log::info!("{}", plan.stats());
    (env, plans)
 }

@@ -373,6 +474,8 @@ fn run_simulation(
    plans: &mut [InteractionPlan],
    last_execution: Arc<Mutex<Execution>>,
 ) -> ExecutionResult {
+    log::info!("Executing database interaction plan...");
+
    let mut states = plans
        .iter()
        .map(|_| InteractionPlanState {
--- a/simulator/model/query.rs
+++ b/simulator/model/query.rs
@@ -154,12 +154,9 @@ pub(crate) struct Insert {

 impl Insert {
    pub(crate) fn shadow(&self, env: &mut SimulatorEnv) {
-        let table = env
-            .tables
-            .iter_mut()
-            .find(|t| t.name == self.table)
-            .unwrap();
-        table.rows.extend(self.values.clone());
+        if let Some(t) = env.tables.iter_mut().find(|t| t.name == self.table) {
+            t.rows.extend(self.values.clone());
+        }
    }
 }

--- a/simulator/model/table.rs
+++ b/simulator/model/table.rs
@@ -46,10 +46,30 @@ impl Display for ColumnType {
    }
 }

+fn float_to_string<S>(float: &f64, serializer: S) -> Result<S::Ok, S::Error>
+where
+    S: serde::Serializer,
+{
+    serializer.serialize_str(&format!("{}", float))
+}
+
+fn string_to_float<'de, D>(deserializer: D) -> Result<f64, D::Error>
+where
+    D: serde::Deserializer<'de>,
+{
+    let s = String::deserialize(deserializer)?;
+    s.parse().map_err(serde::de::Error::custom)
+}
+
 #[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
 pub(crate) enum Value {
    Null,
    Integer(i64),
+    // we use custom serialization to preserve float precision
+    #[serde(
+        serialize_with = "float_to_string",
+        deserialize_with = "string_to_float"
+    )]
    Float(f64),
    Text(String),
    Blob(Vec<u8>),
--- a/simulator/runner/cli.rs
+++ b/simulator/runner/cli.rs
@@ -43,6 +43,12 @@ pub struct SimulatorCLI {
    pub shrink: bool,
    #[clap(short = 'l', long, help = "load plan from a file")]
    pub load: Option<String>,
+    #[clap(
+        short = 'w',
+        long,
+        help = "enable watch mode that reruns the simulation on file changes"
+    )]
+    pub watch: bool,
 }

 impl SimulatorCLI {
@@ -58,6 +64,11 @@ impl SimulatorCLI {
            return Err("Minimum size cannot be greater than maximum size".to_string());
        }

+        // Make sure uncompatible options are not set
+        if self.shrink && self.doublecheck {
+            return Err("Cannot use shrink and doublecheck at the same time".to_string());
+        }
+
        if let Some(plan_path) = &self.load {
            std::fs::File::open(plan_path)
                .map_err(|_| format!("Plan file '{}' could not be opened", plan_path))?;
--- a/simulator/runner/env.rs
+++ b/simulator/runner/env.rs
@@ -56,6 +56,11 @@ impl SimulatorEnv {

        let io = Arc::new(SimulatorIO::new(seed, opts.page_size).unwrap());

+        // Remove existing database file if it exists
+        if db_path.exists() {
+            std::fs::remove_file(db_path).unwrap();
+        }
+
        let db = match Database::open_file(io.clone(), db_path.to_str().unwrap()) {
            Ok(db) => db,
            Err(e) => {
--- a/simulator/runner/execution.rs
+++ b/simulator/runner/execution.rs
@@ -36,7 +36,7 @@ pub(crate) struct ExecutionHistory {
 }

 impl ExecutionHistory {
-    fn new() -> Self {
+    pub(crate) fn new() -> Self {
        Self {
            history: Vec::new(),
        }
@@ -49,7 +49,7 @@ pub(crate) struct ExecutionResult {
 }

 impl ExecutionResult {
-    fn new(history: ExecutionHistory, error: Option<LimboError>) -> Self {
+    pub(crate) fn new(history: ExecutionHistory, error: Option<LimboError>) -> Self {
        Self { history, error }
    }
 }
@@ -156,14 +156,14 @@ fn execute_plan(
 /// `execute_interaction` uses this type in conjunction with a result, where
 /// the `Err` case indicates a full-stop due to a bug, and the `Ok` case
 /// indicates the next step in the plan.
-enum ExecutionContinuation {
+pub(crate) enum ExecutionContinuation {
    /// Default continuation, execute the next interaction.
    NextInteraction,
    /// Typically used in the case of preconditions failures, skip to the next property.
    NextProperty,
 }

-fn execute_interaction(
+pub(crate) fn execute_interaction(
    env: &mut SimulatorEnv,
    connection_index: usize,
    interaction: &Interaction,
--- a/simulator/runner/mod.rs
+++ b/simulator/runner/mod.rs
@@ -4,3 +4,4 @@ pub mod execution;
 #[allow(dead_code)]
 pub mod file;
 pub mod io;
+pub mod watch;
--- a/simulator/runner/watch.rs
+++ b/simulator/runner/watch.rs
@@ -0,0 +1,133 @@
+use std::sync::{Arc, Mutex};
+
+use crate::{
+    generation::{
+        pick_index,
+        plan::{Interaction, InteractionPlanState},
+    },
+    runner::execution::ExecutionContinuation,
+};
+
+use super::{
+    env::{SimConnection, SimulatorEnv},
+    execution::{execute_interaction, Execution, ExecutionHistory, ExecutionResult},
+};
+
+pub(crate) fn run_simulation(
+    env: Arc<Mutex<SimulatorEnv>>,
+    plans: &mut [Vec<Vec<Interaction>>],
+    last_execution: Arc<Mutex<Execution>>,
+) -> ExecutionResult {
+    let mut states = plans
+        .iter()
+        .map(|_| InteractionPlanState {
+            stack: vec![],
+            interaction_pointer: 0,
+            secondary_pointer: 0,
+        })
+        .collect::<Vec<_>>();
+    let result = execute_plans(env.clone(), plans, &mut states, last_execution);
+
+    let env = env.lock().unwrap();
+    env.io.print_stats();
+
+    log::info!("Simulation completed");
+
+    result
+}
+
+pub(crate) fn execute_plans(
+    env: Arc<Mutex<SimulatorEnv>>,
+    plans: &mut [Vec<Vec<Interaction>>],
+    states: &mut [InteractionPlanState],
+    last_execution: Arc<Mutex<Execution>>,
+) -> ExecutionResult {
+    let mut history = ExecutionHistory::new();
+    let now = std::time::Instant::now();
+    let mut env = env.lock().unwrap();
+    for _tick in 0..env.opts.ticks {
+        // Pick the connection to interact with
+        let connection_index = pick_index(env.connections.len(), &mut env.rng);
+        let state = &mut states[connection_index];
+
+        history.history.push(Execution::new(
+            connection_index,
+            state.interaction_pointer,
+            state.secondary_pointer,
+        ));
+        let mut last_execution = last_execution.lock().unwrap();
+        last_execution.connection_index = connection_index;
+        last_execution.interaction_index = state.interaction_pointer;
+        last_execution.secondary_index = state.secondary_pointer;
+        // Execute the interaction for the selected connection
+        match execute_plan(&mut env, connection_index, plans, states) {
+            Ok(_) => {}
+            Err(err) => {
+                return ExecutionResult::new(history, Some(err));
+            }
+        }
+        // Check if the maximum time for the simulation has been reached
+        if now.elapsed().as_secs() >= env.opts.max_time_simulation as u64 {
+            return ExecutionResult::new(
+                history,
+                Some(limbo_core::LimboError::InternalError(
+                    "maximum time for simulation reached".into(),
+                )),
+            );
+        }
+    }
+
+    ExecutionResult::new(history, None)
+}
+
+fn execute_plan(
+    env: &mut SimulatorEnv,
+    connection_index: usize,
+    plans: &mut [Vec<Vec<Interaction>>],
+    states: &mut [InteractionPlanState],
+) -> limbo_core::Result<()> {
+    let connection = &env.connections[connection_index];
+    let plan = &mut plans[connection_index];
+    let state = &mut states[connection_index];
+
+    if state.interaction_pointer >= plan.len() {
+        return Ok(());
+    }
+
+    let interaction = &plan[state.interaction_pointer][state.secondary_pointer];
+
+    if let SimConnection::Disconnected = connection {
+        log::info!("connecting {}", connection_index);
+        env.connections[connection_index] = SimConnection::Connected(env.db.connect());
+    } else {
+        match execute_interaction(env, connection_index, interaction, &mut state.stack) {
+            Ok(next_execution) => {
+                log::debug!("connection {} processed", connection_index);
+                // Move to the next interaction or property
+                match next_execution {
+                    ExecutionContinuation::NextInteraction => {
+                        if state.secondary_pointer + 1 >= plan[state.interaction_pointer].len() {
+                            // If we have reached the end of the interactions for this property, move to the next property
+                            state.interaction_pointer += 1;
+                            state.secondary_pointer = 0;
+                        } else {
+                            // Otherwise, move to the next interaction
+                            state.secondary_pointer += 1;
+                        }
+                    }
+                    ExecutionContinuation::NextProperty => {
+                        // Skip to the next property
+                        state.interaction_pointer += 1;
+                        state.secondary_pointer = 0;
+                    }
+                }
+            }
+            Err(err) => {
+                log::error!("error {}", err);
+                return Err(err);
+            }
+        }
+    }
+
+    Ok(())
+}