fix(apple): push edge cases from review

[ArnabChatterjee20k]

What does this PR do?

Fixes edge cases found in a review of #2000's push code. Stacked on #2000.

#	Edge case	Finding	Change
1	App live, its banner not posted yet (for example a data-only message)	Real. The extension fetched with the same session and client id, and took the app's MQTT connection over.	The extension waits up to one heartbeat (3 s + 1 s) for the app's banner or its next heartbeat. Either means the app is running and has the message, so the extension doesn't connect. It fetches only when neither comes, as after a kill. The running app clears the placeholders it has the messages for on each heartbeat.
2	Sign-out ordering: close(), then deleteSession before the target DELETE	Not an orphan. DELETE /account/sessions/:id queues DELETE_TYPE_SESSION_TARGETS, and the server deletes the session's targets and their subscribers. The SDK's own DELETE is then redundant (401, ignored).	None. Revoking sessions through the Users API queues no cleanup; that's on the appwrite/appwrite#14302 list.
3	AppwritePushAppGroup missing or signed out	Real. The extension has no session and leaves the placeholder, silently.	A background subscription without the App Group warns once, and so does the extension when it has no session.
4	Background filters change between launches	Real. A placeholder was cleared only once all its topics were subscribed again, so one for a dropped or renamed filter stayed.	The launch's reconcile (#2022) also clears placeholders for topics no background subscription claims.
5	Environment detection defaults to production	Intended. App Store builds have no embedded.mobileprovision and must be production. Only a profile that exists but can't be parsed hits the default.	None.
6	A token change re-registers a Push with no background subscription	Real. It could re-create a target the reconcile or close() had deleted.	A token change registers only Push objects with background subscriptions.
7	Dedup needs a messageId	Holds. The server stamps every message with one, and the hand-off relies on the broker's per-session delivery.	None.

It also includes #2025 (merged in): the Swift and Apple clients now send Accept-Encoding: gzip. NIO asked for deflate, gzip, and Appwrite answers deflate with raw deflate rather than zlib, so every compressed response failed with DecompressionError.inflationError(-3). That was one of the errors that stopped APNs registration in the device test on #2000. Against a local Appwrite: 60 of 60 account.get() calls failed before the change, and none after.

The PR also puts Deliveries' doc comment back on Deliveries; #2022 had left it above LinkedTopics.

Test Plan

• 26 Swift Testing tests (1 new: the last heartbeat is kept).
• swift format lint --strict; macOS, iOS Simulator and Linux (swift:6.1-jammy, from the e2e fixture) builds; Generation suite and Twig lint.
• Simulator against a real Appwrite, for 1, 3 and 4. The local stack is down; to rerun once it's back up with tools/runbook.php in the test app.

Related PRs and Issues

• Stacked on feat(apple): background push through APNs #2000.
• feat(messaging): wake APNS/FCM devices for Appwrite (MQTT) push appwrite#14302: sending the placeholder only after the device's session hasn't acknowledged the message makes case 1 rare.

[hansi-codes]

🟢 Tier S · Ready to merge

The reviewed changes have no actionable defects.

The Apple push templates coordinate notification-extension fetching with app heartbeats, diagnose missing App Group or session setup, and reconcile stale placeholders and targets as background subscriptions change. They also avoid registering APNs targets for Push instances without background subscriptions. The Apple and Swift HTTP clients now explicitly request gzip for decompression-enabled requests while preserving any caller-supplied Accept-Encoding header.

Latest changes: The newest commits add an explicit gzip Accept-Encoding header in both Apple and Swift clients when no caller-provided encoding is present, with Apple respecting its compression setting.

Verdict	New comments	Fixed	Still open
✅ Approved	0	0	0

📂 Walkthrough · 5

File	Change
templates/apple/Sources/Client.swift.twig	Adds an explicit gzip request header when compression is enabled and no Accept-Encoding header was supplied.
templates/apple/Sources/Services/Push.swift.twig	Adds push setup diagnostics and reconciles background subscriptions, APNs targets, and stale placeholders.
templates/apple/Sources/Services/PushServiceExtension.swift.twig	Waits for app banner or heartbeat activity before the extension fetches push content.
templates/apple/Tests/PushTests.swift.twig	Tests that the latest heartbeat timestamp is retained and read.
templates/swift/Sources/Client.swift.twig	Adds an explicit gzip request header when no Accept-Encoding header was supplied.

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_{Reviewed the commits since ea709e6 · Details · Comment @hansi-codes review to re-run, or mention @hansi-codes with a question.}

[hansi-codes]

🔵 Tier A · See the inline comments. Summary

[hansi-codes]

🟢 Tier S · Looks good to merge. Summary