[DX-1211] Add strictMode client option and granted-mode checks on subscribe and presence.get#505
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[DX-1211] Add strictMode client option and granted-mode checks on subscribe and presence.get#505umair-ably wants to merge 1 commit into
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… presence.get New spec points TO3r (strictMode ClientOptions attribute), RTL7i (RealtimeChannel#subscribe checks granted modes for SUBSCRIBE) and RTP11f (RealtimePresence#get checks granted modes for PRESENCE_SUBSCRIBE), so that operations whose effect depends on a channel mode the server did not grant fail with an ErrorInfo (strictMode true) or log a warning while preserving their legacy silent result (strictMode false, the default). Reference implementation: ably/ably-js#2236. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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…roposed spec points Spec point IDs RTL7i1/RTL7i2 and RTP11f1/RTP11f2 are proposed in ably/specification#505 and are provisional until that PR merges. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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Author's Note
Extends spec to include new strictMode behaviour as implemented in ably/ably-js#2236. Spec changes highlight whether the error is thrown or logged for previously silent subscribe and presence errors caused by channel mode mismatches.
What: Specifies the behaviour when a client performs an operation whose effect depends on a channel mode the server did not grant:
RealtimeChannel#subscribewithoutSUBSCRIBE(newRTL7i) andRealtimePresence#getwithoutPRESENCE_SUBSCRIBE(newRTP11f). Adds astrictModeclient option (TO3r) that selects between failing the operation (true) and the legacy silent result plus anERROR-level log (false, the default), allowing SDKs to ship the fix additively before a future major version flips the default.Why: Today these calls fail silently —
presence.get()resolves with[]andsubscribe()registers a listener that never fires. This is a significant DX trap for both humans and coding agents (see ably/ably-js#2236 for experiments quantifying agent failure rates: 50% unrecoverable → 0% with strict failures). The checks use the granted mode set (RTL4m), not the requested modes, so they also catch the case where a capability restriction caused the server to silently drop a requested mode.Error codes: 90009 (
subscribe_mode_not_enabled) and 91008 (presence_subscribe_mode_not_enabled) are already registered in ably-common.Deliberately out of scope: presence enter/update/leave without the
presencemode (the server NACKs those, so they are not silent); theErrorInforemediation/hint field ably-js attaches to these errors (naming under separate discussion); and the annotations mode check (RTAN4e), where ably-js already fails the call today — deviating from other SDKs, which log per the current spec text — sostrictModegating is not necessary there to preserve existing behaviour.Reference implementation: ably/ably-js#2236.
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