rea/website/evidence/calculator-and-dino.md

Calculator and dinosaur beginner examples

Evidence collected on 9 October 2026 with the published REA 4.1.0 package. The homepage offers compact setup first, then a reverse-engineering definition, purpose and manual/agent comparison. Dinosaur is the first worked example; Calculator is the second. Each states its goal, why the program is inspected, what REA returned and how the agent uses it. Prompts and replies are examples based on the findings below. Selected code and generic inputs are public; raw captures stay outside the website.

Windows Calculator

Inspected artifacts

The installed Windows Calculator package is version 11.2508.4.0, x64.

Artifact	SHA-256
Windows calc.exe launcher	9c2c8a8588fe6db09c09337e78437cb056cd557db1bcf5240112cbfb7b600efb
Package CalcViewModel.dll	07a1953bbf828a3495662c4b4bde1c80c9075061e0e389eabac5f8c544710df5

REA's function dossier for launcher 0x1400019f4 includes the call to ShellExecuteW with ms-calculator:. Evidence: ev_e97a6a1a61bfe63476a13e6285d71dd838101066f7863c9af822861050203ea5.

The calculation is in the installed app's model DLL. REA inspected function 0x1801245d0, whose body occupies two ranges, totaling 10,656 bytes: 0x1801245d0–0x180126f4c and 0x180126f55–0x180126f77. Evidence: ev_830a710c7fb55a08ac896fb5783c14339480a57a96d6d45c57c024b6a43239d0.

REA supplied pseudocode, original instructions, calls and references. Its case 0x76 checks the operator field against 0x5c and 0x5b and constructs the constant 100 in both paths. One path divides the current value by 100; the other combines the current value with the previous value divided by 100. The published assembly is selected exactly from the returned instruction list.

The opening manual/agent comparison selects instructions at 0x180124945–0x180124992 and 0x180124a14–0x180124a34, with explicit omissions. Its three highlights identify the operator comparisons, construction of 100 and arithmetic helper calls, and the final multiplication path. The analyst thought bubbles illustrate the work of decoding those facts; they are not a recorded analyst transcript or a measured comparison of investigation times. The same percentage question appears in the agent prompt. Helper meanings and operator names are interpretations checked against the public source below.

The binary is stripped. A local instruction scan located candidates using operator IDs and the constant 100; REA then produced the complete function dossier. Function selection was analyst-assisted. The illustrative agent prompt is not a recording of an autonomous end-to-end discovery.

Source interpretation and check

Microsoft's MIT-licensed source at commit d125246a4e19842ce1332e6c7839cf0e110027d8 supplies the operator meanings and an independently readable implementation:

• Operator IDs: IDC_DIV = 91, IDC_MUL = 92, IDC_PERCENT = 118.
• Percentage branch: multiply/divide uses rat / 100; other operators use rat * (m_lastVal / 100).
• Standard-mode tests: 6 × 6 % = 0.36 and 50 + 20 % = 60.

These source branches agree with the operator checks and two paths observed in the installed DLL. The public source commit is a crosscheck; it is not an identified build commit for that installed package. No PDB symbols were loaded.

The homepage's named C-like rule is an explanatory summary. Its 200 + 10% and 200 × 10% controls compute those cases from that rule using the fixed inputs 200 and 10. Browser checks exercise both percentage illustrations, their results, operator selection and reset. The Microsoft tests were inspected, not executed. A probe-owned Calculator window could be inspected, but it was no longer present at the input-check step; no completed Windows GUI input result is claimed.

Dinosaur speed

Running target and source

REA inspected the HTTP page https://wayou.github.io/t-rex-runner/ in an owned Chrome 150.0.7871.124 session through a loopback debugging connection. This is wayou's Chromium-derived browser edition. REA's HTTP(S) page inspection does not select chrome://dino/; the website identifies the HTTP edition as its target.

The returned index.js source contains 90,241 UTF-8 bytes, SHA-256 e7a50d337bdbe4299068de034e4564cfe5fd45ca9257ded37b6ada9330cedf0f. Evidence: ev_7a09de570cf6b64907504046485cab69ad444828964106eabc05958799749905.

This digest also matches index.js in repository commit 5455bfa408ec6b707c7300ff194b7390733a766d. Source locations:

• Settings: ACCELERATION: 0.001, MAX_SPEED: 13, SPEED: 6.
• Update branch: increment speed on a collision-free update while speed is below the threshold.

The source begins with the Chromium Authors' 2014 copyright notice. Selected excerpts are credited on the page. The repository's BSD license and the source copyright are reproduced in public/assets/licenses/dinosaur.txt.

Controlled original-game check

After the passive REA inspection, a separate Playwright controller called the original page's Runner.update() repeatedly. It disabled future update scheduling and obstacle generation, set the starting speed to 6, and kept the game in its playing state. The control is credited separately from REA's read-only inspection.

Update count	Observed speed	Display rounded to 3 decimals
0	6	6.000
1,000	7.000000000000334	7.000
4,000	9.99999999999956	10.000
7,000	12.999999999997897	13.000
10,000	13.000999999997896	13.001

The branch compares before adding. Floating-point increments can cross the threshold by one increment; the reconstruction preserves this behavior rather than introducing a clamp.

New game and reader experiment

public/assets/dino-speed.js contains the reconstructed rule and an update-count replay. Its rounded results match the original-game check above. The website's mini-game imports this rule. It advances its own simulation at 60 updates per second, avoiding a different frame rate changing its demonstration pace.

The canvas drawing, dinosaur shape, jump physics, rectangle collision detection, spacing and controls are newly authored teaching code. The reconstruction claim is scoped to the speed rule. Changing the slider selects a fixed speed between 2 and 18; selecting automatic acceleration restores the starting speed of 6.

The new game starts only after user input. It supports Play/Pause, Jump, Restart, canvas Space/Up keys and touch. It pauses when hidden or scrolled out of view. Without JavaScript, a static SVG, source excerpts and recorded results remain available. The downloadable speed module and complete game source are linked from the lab.

Review checks

Website checks cover root and /rea/ hosting, 320/390/850/1440px layouts, expanded evidence, copying, no-JavaScript content, reduced motion, the two percentage rules and the game controls. Game checks include speed selection, automatic acceleration, a collision, restart, jump height on the rendered canvas, pause and the original-rule replay. Existing Notes and DX-Ball pages remain part of layout checks.