Document wait endpoint exception and mandatory duration logging

CONTRIBUTING.md

@@ -1,5 +1,7 @@
 # Contributing
 
+**Wait-endpoint exception:** API endpoints whose purpose is to wait for an event or status change (including long polling) are exempt from the 100ms response deadline. Their HTTP request may remain open for that wait; it must not be cut off at 100ms or fail review or CI solely because of that duration. This exception applies to the response-deadline rules throughout this document. Every individual wait request must be logged with its actual waiting duration; the response-deadline exception does not remove this documentation duty. All other quality requirements remain applicable. It does not permit forwarding a known endpoint. This is a rule clarification; implementing wait endpoints is separate work.
+
 ## Deviating From These Rules
 
 These guidelines are binding. A pull request that knowingly does not meet one of

README.md

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 # front-api
 
+**Wait-endpoint exception:** API endpoints whose purpose is to wait for an event or status change (including long polling) are exempt from the 100ms response deadline. Their HTTP request may remain open for that wait; it must not be cut off at 100ms or fail review or CI solely because of that duration. This exception applies to the response-deadline rules throughout this document. Every individual wait request must be logged with its actual waiting duration; the response-deadline exception does not remove this documentation duty. All other quality requirements remain applicable. It does not permit forwarding a known endpoint. This is a rule clarification; implementing wait endpoints is separate work.
+
 Public HTTP layer in front of the DFX backend. Listed routes (`GET`/`HEAD /` 302 to swagger, `/version`, a filtered swagger snapshot, GET/HEAD cache, optional Postgres reads for country/language) are completed locally within 100ms, never forwarded, and never wait on `BACKEND_URL` for that client request. Background cache and swagger refresh may ping the upstream HTTP backend. Unlisted traffic is forwarded.
 
 ## Run

REVIEW.md

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 # Review
 
+**Wait-endpoint exception:** API endpoints whose purpose is to wait for an event or status change (including long polling) are exempt from the 100ms response deadline. Their HTTP request may remain open for that wait; it must not be cut off at 100ms or fail review or CI solely because of that duration. This exception applies to the response-deadline rules throughout this document. Every individual wait request must be logged with its actual waiting duration; the response-deadline exception does not remove this documentation duty. All other quality requirements remain applicable. It does not permit forwarding a known endpoint. This is a rule clarification; implementing wait endpoints is separate work.
+
 This is the contract for a standard pull-request review in this repository. It
 is not a second copy of [CONTRIBUTING.md](CONTRIBUTING.md). Each item is pass
 or fail. Any fail keeps the pull request as a draft or on changes requested.