diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..569ce8d
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,32 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+
+jobs:
+  ci:
+    name: Check, test, lint
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: rustfmt, clippy
+
+      - uses: Swatinem/rust-cache@v2
+
+      - name: Format
+        run: cargo fmt --check
+
+      - name: Build
+        run: cargo build
+
+      - name: Clippy
+        run: cargo clippy -- -D warnings
+
+      - name: Test
+        run: cargo test
diff --git a/p/src/commands/ls.rs b/p/src/commands/ls.rs
index 3bf1ebb..a851287 100644
--- a/p/src/commands/ls.rs
+++ b/p/src/commands/ls.rs
@@ -44,18 +44,15 @@ pub fn execute() -> Result<()> {
                 let now = chrono::Utc::now().timestamp();
                 for &i in indices {
                     let id = jobs[i].id.clone();
-                    if let Some(maybe_ec) = results.get(&id) {
-                        if let Some(ec) = maybe_ec {
-                            jobs[i].status = if *ec == 0 {
-                                JobStatus::Done
-                            } else {
-                                JobStatus::Failed
-                            };
-                            jobs[i].exit_code = Some(*ec);
-                            jobs[i].finished_at = Some(now);
-                            db::save(&jobs[i])?;
-                        }
-                        // None means still running — no update needed.
+                    if let Some(Some(ec)) = results.get(&id) {
+                        jobs[i].status = if *ec == 0 {
+                            JobStatus::Done
+                        } else {
+                            JobStatus::Failed
+                        };
+                        jobs[i].exit_code = Some(*ec);
+                        jobs[i].finished_at = Some(now);
+                        db::save(&jobs[i])?;
                     }
                 }
             }
diff --git a/p/src/config.rs b/p/src/config.rs
index ba9e4c4..4e7f560 100644
--- a/p/src/config.rs
+++ b/p/src/config.rs
@@ -72,3 +72,68 @@ impl Config {
         }
     }
 }
+
+// ── Tests ─────────────────────────────────────────────────────────────────────
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn two_worker_config() -> Config {
+        Config {
+            default_worker: Some("beefy".to_string()),
+            workers: vec![
+                WorkerConfig {
+                    name: "beefy".to_string(),
+                    connection: "user@192.168.1.50".to_string(),
+                },
+                WorkerConfig {
+                    name: "cloud".to_string(),
+                    connection: "user@cloud.example.com".to_string(),
+                },
+            ],
+        }
+    }
+
+    #[test]
+    fn get_worker_found() {
+        assert!(two_worker_config().get_worker("beefy").is_some());
+    }
+
+    #[test]
+    fn get_worker_not_found() {
+        assert!(two_worker_config().get_worker("unknown").is_none());
+    }
+
+    #[test]
+    fn default_worker_returns_correct_name() {
+        let cfg = two_worker_config();
+        assert_eq!(cfg.default_worker().unwrap().name, "beefy");
+    }
+
+    #[test]
+    fn resolve_worker_by_name() {
+        let cfg = two_worker_config();
+        assert_eq!(cfg.resolve_worker(Some("cloud")).unwrap().name, "cloud");
+    }
+
+    #[test]
+    fn resolve_worker_falls_back_to_default() {
+        let cfg = two_worker_config();
+        assert_eq!(cfg.resolve_worker(None).unwrap().name, "beefy");
+    }
+
+    #[test]
+    fn resolve_worker_unknown_name_errors() {
+        assert!(two_worker_config().resolve_worker(Some("unknown")).is_err());
+    }
+
+    #[test]
+    fn resolve_worker_no_default_errors() {
+        let cfg = Config {
+            default_worker: None,
+            workers: vec![],
+        };
+        assert!(cfg.resolve_worker(None).is_err());
+    }
+}
diff --git a/p/src/db.rs b/p/src/db.rs
index 5f59a85..c243685 100644
--- a/p/src/db.rs
+++ b/p/src/db.rs
@@ -31,19 +31,6 @@ pub fn save(job: &Job) -> Result<()> {
         .with_context(|| format!("failed to write job {}", job.id))
 }
 
-/// Load a job by exact UUID.
-pub fn load(id: &str) -> Result<Option<Job>> {
-    let path = job_path(id)?;
-    if !path.exists() {
-        return Ok(None);
-    }
-    let content =
-        std::fs::read_to_string(&path).with_context(|| format!("failed to read job {}", id))?;
-    serde_json::from_str(&content)
-        .with_context(|| format!("failed to parse job {}", id))
-        .map(Some)
-}
-
 /// Find a job by UUID prefix. Errors if the prefix is ambiguous.
 pub fn find(prefix: &str) -> Result<Option<Job>> {
     let dir = jobs_dir()?;
@@ -111,3 +98,58 @@ pub fn delete(id: &str) -> Result<()> {
     }
     Ok(())
 }
+
+// ── Tests ─────────────────────────────────────────────────────────────────────
+
+#[cfg(test)]
+mod tests {
+    use crate::job::{Job, JobStatus};
+
+    fn sample_job() -> Job {
+        Job {
+            id: "a3f2b091-1234-5678-9abc-000000000000".to_string(),
+            worker: "beefy".to_string(),
+            cwd: "/home/user/projects".to_string(),
+            command: "make".to_string(),
+            started_at: 1_700_000_000,
+            finished_at: Some(1_700_000_060),
+            exit_code: Some(0),
+            status: JobStatus::Done,
+        }
+    }
+
+    #[test]
+    fn job_json_roundtrip() {
+        let job = sample_job();
+        let json = serde_json::to_string_pretty(&job).unwrap();
+        let decoded: Job = serde_json::from_str(&json).unwrap();
+        assert_eq!(decoded.id, job.id);
+        assert_eq!(decoded.worker, job.worker);
+        assert_eq!(decoded.command, job.command);
+        assert_eq!(decoded.exit_code, job.exit_code);
+        assert_eq!(decoded.status, job.status);
+    }
+
+    #[test]
+    fn status_serialises_lowercase() {
+        let job = sample_job();
+        let json = serde_json::to_string(&job).unwrap();
+        assert!(
+            json.contains("\"done\""),
+            "status should serialise as lowercase \"done\""
+        );
+    }
+
+    #[test]
+    fn running_job_has_no_exit_code_in_json() {
+        let job = Job {
+            status: JobStatus::Running,
+            finished_at: None,
+            exit_code: None,
+            ..sample_job()
+        };
+        let json = serde_json::to_string(&job).unwrap();
+        assert!(json.contains("\"running\""));
+        assert!(json.contains("\"exit_code\":null"));
+    }
+}
diff --git a/p/src/job.rs b/p/src/job.rs
index f3893fb..25da123 100644
--- a/p/src/job.rs
+++ b/p/src/job.rs
@@ -35,16 +35,6 @@ impl JobStatus {
             Self::Unknown => "unknown",
         }
     }
-
-    pub fn from_str(s: &str) -> Self {
-        match s {
-            "running" => Self::Running,
-            "done" => Self::Done,
-            "failed" => Self::Failed,
-            "stopped" => Self::Stopped,
-            _ => Self::Unknown,
-        }
-    }
 }
 
 // ── Display helpers ───────────────────────────────────────────────────────────
@@ -100,3 +90,112 @@ impl Job {
         }
     }
 }
+
+// ── Tests ─────────────────────────────────────────────────────────────────────
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn sample_job() -> Job {
+        Job {
+            id: "a3f2b091-1234-5678-9abc-000000000000".to_string(),
+            worker: "beefy".to_string(),
+            cwd: "/home/user/projects/foo".to_string(),
+            command: "make".to_string(),
+            started_at: 1_700_000_000,
+            finished_at: None,
+            exit_code: None,
+            status: JobStatus::Running,
+        }
+    }
+
+    #[test]
+    fn short_id_is_first_8_chars() {
+        assert_eq!(sample_job().short_id(), "a3f2b091");
+    }
+
+    #[test]
+    fn status_display_running() {
+        assert_eq!(sample_job().status_display(), "running");
+    }
+
+    #[test]
+    fn status_display_done() {
+        let job = Job {
+            status: JobStatus::Done,
+            exit_code: Some(0),
+            ..sample_job()
+        };
+        assert_eq!(job.status_display(), "done [0]");
+    }
+
+    #[test]
+    fn status_display_failed() {
+        let job = Job {
+            status: JobStatus::Failed,
+            exit_code: Some(2),
+            ..sample_job()
+        };
+        assert_eq!(job.status_display(), "failed [2]");
+    }
+
+    #[test]
+    fn status_display_stopped() {
+        let job = Job {
+            status: JobStatus::Stopped,
+            ..sample_job()
+        };
+        assert_eq!(job.status_display(), "stopped");
+    }
+
+    #[test]
+    fn duration_display_minutes_seconds() {
+        let job = Job {
+            started_at: 1_000,
+            finished_at: Some(1_065),
+            ..sample_job()
+        };
+        assert_eq!(job.duration_display(), "1:05");
+    }
+
+    #[test]
+    fn duration_display_hours() {
+        let job = Job {
+            started_at: 0,
+            finished_at: Some(3_661),
+            ..sample_job()
+        };
+        assert_eq!(job.duration_display(), "1:01:01");
+    }
+
+    #[test]
+    fn command_display_no_truncation() {
+        assert_eq!(sample_job().command_display(50), "make");
+    }
+
+    #[test]
+    fn command_display_truncated() {
+        assert_eq!(sample_job().command_display(3), "ma…");
+    }
+
+    #[test]
+    fn cwd_display_outside_home() {
+        let job = Job {
+            cwd: "/var/tmp/something".to_string(),
+            ..sample_job()
+        };
+        assert_eq!(job.cwd_display(), "/var/tmp/something");
+    }
+
+    #[test]
+    fn cwd_display_under_home() {
+        if let Some(home) = dirs::home_dir() {
+            let job = Job {
+                cwd: home.join("projects/foo").to_string_lossy().to_string(),
+                ..sample_job()
+            };
+            assert_eq!(job.cwd_display(), "~/projects/foo");
+        }
+    }
+}
diff --git a/p/src/ssh.rs b/p/src/ssh.rs
index 8afad35..d2d51a8 100644
--- a/p/src/ssh.rs
+++ b/p/src/ssh.rs
@@ -161,3 +161,66 @@ pub fn poll_jobs(worker: &WorkerConfig, job_ids: &[&str]) -> Result<HashMap<Stri
     }
     Ok(map)
 }
+
+// ── Tests ─────────────────────────────────────────────────────────────────────
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn parse_user_at_host() {
+        let (uh, port) = parse_connection("user@host.local");
+        assert_eq!(uh, "user@host.local");
+        assert_eq!(port, None);
+    }
+
+    #[test]
+    fn parse_user_at_host_with_port() {
+        let (uh, port) = parse_connection("user@host.local:2222");
+        assert_eq!(uh, "user@host.local");
+        assert_eq!(port, Some(2222));
+    }
+
+    #[test]
+    fn parse_bare_host() {
+        let (uh, port) = parse_connection("myserver");
+        assert_eq!(uh, "myserver");
+        assert_eq!(port, None);
+    }
+
+    #[test]
+    fn parse_host_with_port() {
+        let (uh, port) = parse_connection("192.168.1.1:22");
+        assert_eq!(uh, "192.168.1.1");
+        assert_eq!(port, Some(22));
+    }
+
+    #[test]
+    fn parse_ssh_alias_unchanged() {
+        // Plain SSH config aliases contain no '@' or ':port' — returned as-is.
+        let (uh, port) = parse_connection("my-dev-box");
+        assert_eq!(uh, "my-dev-box");
+        assert_eq!(port, None);
+    }
+
+    #[test]
+    fn hostname_strips_user_prefix() {
+        assert_eq!(hostname_from_connection("user@host.local"), "host.local");
+    }
+
+    #[test]
+    fn hostname_strips_user_and_port() {
+        assert_eq!(hostname_from_connection("user@host.local:22"), "host.local");
+    }
+
+    #[test]
+    fn hostname_from_bare_host() {
+        assert_eq!(hostname_from_connection("myserver"), "myserver");
+    }
+
+    #[test]
+    fn hostname_from_ssh_alias() {
+        assert_eq!(hostname_from_connection("my-dev-box"), "my-dev-box");
+    }
+}