Challenge 1: Why the Proxy Headers Live in the Outer server Block — Solution Walkthrough

Why this placement is deliberate:

Per Chapter 6's own warning box, if a nested location block sets even
one proxy_set_header of its own, it stops inheriting ALL
proxy_set_header directives from the parent context — not just the
one it overrides. Placing X-Forwarded-For, X-Forwarded-Proto, and
X-Real-IP in the outer server {} block, and never setting any
proxy_set_header directly inside the /api/ location block itself,
means /api/ automatically inherits all three headers without needing
to repeat them.

What would go wrong with the alternative:

If these three headers had instead been set inside the /api/ location
block itself, and any future location block were added elsewhere in
the same server without also repeating them, that new location would
silently receive none of these forwarded headers at all — exactly the
gotcha Chapter 6 warned about. Keeping them in the outer block avoids
this risk entirely for every current and future location nested
inside this server, as long as none of those locations add their own
proxy_set_header without also repeating the parent's headers.

WHY THIS WORKS AS AN ANSWER
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This exercise checks that the capstone's own specific structural
choice is recognized as a direct, deliberate application of Chapter
6's own inheritance gotcha, not an arbitrary organizational preference.