35. The Patribots, four years

One team, four seasons, a clean monotonic climb — 5.0 → 10.0 → 17.5 → 20.0 — and one number that never moved. (One asterisk on the series up front: 2024’s 17.5 is the repo’s final state, reflecting an offseason rebuild — the robot that actually competed that season scored closer to ~12; the 2024 section below has the commit evidence.) This is the worked longitudinal case study: FRC 4738, the Patribots, scored against the full D1–D8 rubric across RapidReact 2022, ChargedUp 2023, Crescendo 2024, and Reefscape 2025. Unlike the corpus survey — shallow clones with .git stripped — these are full clones with complete commit history, which is what lets us say not just what the code became but when it became it. Every level below was confirmed by opening the files behind the grep hits; presence alone was never enough. Read down a column and you see a team improving. Read across the years and you see two rules illustrated on the same repo: rewrite in the offseason, and great code can still have a glaring gap.

The four-year scoresheet

One row differs from the San Diego scoresheet, which lists 2025 at Σ = 19.5 with D2 = 2.5: this full-history read confirmed the Superstructure’s guarded transitions (described under 2025 below) and raised D2 to 3, for Σ = 20.0.

The score doubles, then nearly doubles again, then settles — a textbook trace up the maturity ladder. Six of eight dimensions rise. One column — D4, testing — reads 0 for all four years. Hold onto that; it is the whole moral of the second half.

What each season actually was

2022 RapidReact — 5.0 — pre-framework. Not command-based at all. Robot.java extends TimedRobot with hand-rolled device wrappers — Motor, MotorGroup, Falcon, Gamepad, Turret — and joystick values flowing straight to motor groups inside the periodic loop. No SubsystemBase, no command composition, no README, no CI. The one forward-looking piece is a Limelight-aimed turret (tx/ty targeting across fifteen files) — targeting only, no pose estimation. A small team (four contributors, ninety-two commits) brute-forcing a working robot. This is the baseline everything else is measured against.

2023 ChargedUp — 10.0 — custom framework, strong on the field. Still not WPILib command-based — zero SubsystemBase, zero CommandBase. The telling move is in the first week of the season: “Convert command to iterative” and “Refactor DriveSubsystem.java to Swerve.java — Delete RobotContainer.java.” They started from a command-based swerve template and deliberately tore out WPILib’s command framework to run their own iterative architecture, organized into hardware/, calc/, and auto/ packages. What is striking is how much capability they reached without the modern scaffolding: PhotonVision AprilTag pose estimation feeding addVisionMeasurement into a SwerveDrivePoseEstimator, dual-camera ambiguity comparison for rejection, drive-to-pose auto-alignment, forty-five PathPlanner paths driven by AutoBuilder. Logging is still SmartDashboard-only; no sim, no tests. README and a build CI arrive. The story of this repo is good results on a foundation they were about to abandon.

2024 Crescendo — 17.5 — two robots in one repo. This is the discontinuity — but the commit history shows the score is half in-season, half offseason rebuild, and the rubric scores the final state. During the actual competition season (January–April) this repo was command-based on the Monologue logging library with no IO layer. Then, entirely in summer, the inflection: 2024-07-30 “switch to loggedrobot and basic setup before big io division,” 2024-08-02 “ampper adapted to adv kit,” 2024-08-21 “gyro???” — the first GyroIO interface. The IO-layer + AdvantageKit architecture that earns the D1/D5 = 3 was built after the season, in July–August 2024, on the same repo. So 17.5 is the repo’s final state; the 2024 competition robot scored closer to ~12. In its final form it carries per-subsystem *IO interfaces across all eleven mechanisms (GyroIO, ShooterIO, PivotIO, IntakeIO, IndexerIO, ClimbIO, ElevatorIO, AmpperIO, LimelightIO, PicoColorSensorIO, MAXSwerveModuleIO), full AdvantageKit @AutoLog inputs, and its autonomous high-water mark — PathPlanner plus Choreo actually wired plus LocalADStar on-the-fly pathfinding. Coordination is command-manager classes (PieceControl, ShooterCmds, ShooterCalc), richer than plain composition but not yet a guarded state machine.

2025 Reefscape — 20.0 — consolidation and a real coordinator. Refinement of the 2024 platform rather than another leap, and it opens already modern — the 2025-01-10 commit is “add claw with akit and logged constants.” The IO seam matures into dual real implementations: *IOKraken and *IONeo for the same interface across elevator, wrist, climb, coral/algae claw, and module — clean hardware portability, one interface, two motors. The season’s intellectual work is coordination: “add superstructure control” (2025-01-12) and a deliberate “start state implementation” (2025-02-12) that becomes a genuine Superstructure. SuperState objects bundle a robot-wide goal into per-subsystem states; a targetState is the requested intent, and transitions are guarded — () -> elevator.atPosition(...) conditions, waitUntil gates — so intent is separated from execution. That is the D2 = 3 anchor. Vision reaches D7 = 3: two Limelights behind a VisionIO interface, MegaTag2, dynamic std-dev tuning and rejection. Fewer commits than 2024, because less was being invented — a refinement year on a stable base.

The leap happened in the offseason

Every season shares the same heartbeat: a January kickoff spike, heavy February–March build-and-compete, an April taper, then a fall bump that is not rewrite work but Beach Blitz — the San Diego offseason event, all “day 1 bb” and tuning commits. The architecture decisions, by contrast, happen at kickoff or in deep summer.

From 2022 to 2023 the Patribots improved within a custom, non-command-based framework — better vision, better autos, the same architectural ceiling. The jump to elite-track scores came from a clean-sheet adoption of the IO-layer + AdvantageKit stack in July–August 2024 — between the Crescendo season and the Reefscape season, on the Crescendo repo, not during any build season. That is why Reefscape 2025 opens already on AdvantageKit with logged constants: the foundation was a finished offseason project before kickoff. The pattern across four years is unambiguous — architecture is decided when there is no game to play, and refined under competition pressure. They are a team that paid the architectural cost most teams never pay, and paid it in the summer. This is the concrete proof behind the foundation-first rule: you do not rewrite your framework in week three of build season; you do it in July.

The four-year zero

Now the gap. Run git log --all -S"@Test" across every branch of every season repo and it returns nothing. Not one unit test has ever been written — the D4 = 0 column is not a snapshot, it is a four-year fact, and D4 is the single rarest marker in the entire San Diego corpus, the clearest signal of a real software-engineering culture.

The cruelty of it is that Patribots own the exact infrastructure that makes testing cheap. The elite-track architecture frames advanced capability as dividends that attach to three seams — the IO seam (D1), the coordination seam (D2), and the state seam (D7/RobotState). They cut the IO seam in 2024 and the coordination seam in 2025. Their @AutoLog inputs structs and per-subsystem IO interfaces are precisely what makes unit testing “a deferred dividend you populate, not a refactor you rebuild.” They built the plumbing and never opened the tap. The simulation story is the same gap in a second form: D3 has never cleared ~2, stuck at a generic DCMotorSim buried in the motor wrappers, instead of mechanism physics in a proper XxxIOSim. These are not two problems. They are one — both attach to the IO seam that already exists.

Prioritized next steps

The retrospective ends where every good one should: with a short, ordered list of the highest-leverage moves, chosen so the top item is the cheapest and rarest.

1. Collect the testing dividend (D4: 0 → 2). The move. Add a real XxxIOSim for one mechanism — start with the elevator or wrist for clean 1-DOF physics — using WPILib ElevatorSim / SingleJointedArmSim inside updateInputs, looping above the line so sim and real share one controller. Write one test that constructs the subsystem with its IOSim and asserts it reaches a setpoint. Then change one line of gradle.yml so CI runs test, not just build, gating merges — which simultaneously pushes toward D4 = 3.
2. Promote simulation from the motor wrapper to the IO layer (D3: 2 → 3). Same seam, same work as step 1: filling XxxIOSim with mechanism physics is the simulation upgrade. Then add a SIM/REPLAY mode switch at the single subsystem-construction point and get AdvantageKit replay of real matches for free — a path to D5 = 4.
3. Build the state seam — a RobotState world model (D7: 3 → 4). The one seam they have not cut. Today the pose estimator lives privately inside Swerve. Extract a dedicated RobotState that owns the SwerveDrivePoseEstimator (later a pose history and game-piece state); subsystems feed it, vision corrects it, pathing and decisions read from it. That is the difference between “pose estimation exists” and “a world model is the architecture.”

When: their own history says summer — the IO layer was a July–August project, the Superstructure a kickoff project. The summer of 2026 is the slot, and unlike 2024 this one needs no demolition, only filling seams that already exist.

If they do exactly one thing: write the first unit test. It is the rarest, longest-standing gap — four years and zero attempts in the entire history — it requires the least new architecture, and it is the clearest available signal that 4738 is an engineering program and not just a strong-results team.

Why this belongs in the book

Use it as a template. Any team can produce this document about itself: pull full history, score each season honestly against the rubric by opening the files, read the scoresheet across time instead of down a column, and let the commit log — not memory — say when the sophistication actually landed. Do that and you will likely find the same two truths the Patribots demonstrate. First, the leap you are proud of probably happened in an offseason, because that is the only time there is room to rewrite a foundation. Second, a genuinely strong codebase — 20 out of 32, elite by any measure — can still carry a single glaring zero for four straight years, precisely because nothing on the field forces you to close it. The retrospective is how you find your own uncollected dividend before someone else scores you and points at it.