fix(api): Activity.timestamp should be string instead of Date (type only)#571
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heyitsaamir wants to merge 2 commits into
Open
fix(api): Activity.timestamp should be string instead of Date (type only)#571heyitsaamir wants to merge 2 commits into
heyitsaamir wants to merge 2 commits into
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The Bot Framework Activity protocol sends these as ISO-8601 strings over JSON (as the existing doc comments already say). Inbound activities are parsed by express.json() with no reviver and Activity.from() is just Object.assign — so at runtime these fields are strings, not Date objects. The Date type was a lie; calling activity.timestamp.toISOString() in a handler would crash. The withTimestamp/withLocalTimestamp builders still accept Date for ergonomics and normalize via toISOString(), so existing call sites keep working.
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Pull request overview
This PR corrects the public typings for Activity.timestamp and Activity.localTimestamp in @microsoft/teams.api to reflect actual runtime behavior: these fields are ISO-8601 strings on inbound activities, not Date objects. It also updates the fluent builder methods to keep accepting Date inputs while normalizing them to ISO strings to avoid breaking common construction patterns.
Changes:
- Change
IActivity.timestamp/localTimestampandActivity.timestamp/localTimestampfromDatetostring. - Update
withTimestampandwithLocalTimestampto acceptDate | string, convertingDateinputs totoISOString().
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heyitsaamir
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rido-min
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May 11, 2026
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Activity.timestampwas lying about being aDate. It's a string. Always was. The doc comment literally says "expressed in ISO-8601 format" two lines above the: Dateannotation 🙃Inbound activities go through
express.json()(no reviver), andActivity.from()is justObject.assign— nothing ever turns it into aDate. Soactivity.timestamp.toISOString()in a handler? Crash.Fix: type
timestampandlocalTimestampasstring.Also removing
withTimestamp()andwithLocalTimestamp()because timestamps set on outgoing bot activities are ignored by the chat service, so those builder helpers were a bit of a footgun/no-op.