Two chapters closed — one went smoothly, one didn't

What I got through

• Finished static inline functions, variadic functions, compound literals, and designated initializers. Passed the chapter test 4/5 (80%) — missed the one about duplicate designated initializers actually being valid C (last one wins, which I didn't know).
• Finished the C standards overview, _Bool/<stdbool.h>, _Static_assert, and the full undefined-behaviour inventory. Failed the chapter test on the first attempt, 2/5 (40%). Retook it and passed 4/5 (80%).
• Started Ring Buffer: got through G1 (wraparound mechanics) clean, no help needed. Traced through G2 fine but ran out of steam before actually writing the code for it, so I pushed it to next session — and I'm opening next time with a full re-study of ring buffers from scratch, because I want to actually nail this one.

Mistakes I made

• Reversed the argument order on va_start and misspelled va_arg as va_args — not the first time I've done that one.
• Wrote a function that ignored its own parameters and just returned a hardcoded value on my first attempt.
• The three misses on my failed UB test: mixed up implementation-defined behaviour with undefined behaviour, got an unsigned wraparound off by one, and knew type punning was wrong but couldn't name it "strict aliasing violation."
• Argued to myself that pointer arithmetic out-of-bounds couldn't really be UB if I never dereference it — I was wrong, and needed a second pass at the reasoning before I accepted it as an actual rule.
• Caught myself using bitwise-AND when the exercise actually wanted modulo, before anyone had to point it out to me.

What's next

Anki deck's up to 384 cards now, from 345. Next session: full ring buffer re-study, finish G2, then move into G3.