feat(cymbal): set posthog-flutter wire-order cutoff

[cat-ph]

Problem

posthog-flutter payloads are currently normalized as legacy crash-first stacks at every version. PostHog/posthog-flutter#467 will make Flutter's Dart path canonical and raise the Android SDK floor to 3.56.0, whose shared throwable coercer is also canonical. Apple-native exceptions are already canonical.

Cymbal must stop reversing events from that Flutter release onward while preserving legacy fingerprint lookup for older issues.

Changes

• set posthog-flutter's canonical_since cutoff to 5.33.0
• cover the version boundary in the existing Android/server cutoff regression test
• keep reverse-order legacy fingerprint reconstruction after the cutoff

Rollout

• Confirm 5.33.0 is still the next unclaimed Flutter minor immediately before merge. feat(surveys): add displaySurvey to show a survey on demand posthog-flutter#495 also carries a minor changeset; if it releases first, update this cutoff and feat: emit error-tracking stack frames in canonical bottom-up order posthog-flutter#467 to 5.34.0.
• Merge and deploy this Cymbal cutoff.
• Merge and release feat: emit error-tracking stack frames in canonical bottom-up order posthog-flutter#467.

Known limitation: already-published Flutter 5.32.1 accepts the dynamic Android range [3.55.0,4.0.0), so some fresh builds can resolve canonical Android 3.56.0 while still reporting Flutter 5.32.1. A Flutter-version cutoff cannot distinguish those builds. The new Flutter release raises the lower bound and establishes a reliable boundary going forward.

Tests

• cargo fmt --all --check
• cargo test -p cymbal modes::processing::normalization::test::android_server_and_flutter_cutoffs_gate_normalization_by_version --lib

[greptile-apps]

_{Reviews (1): Last reviewed commit: "feat(cymbal): set posthog-flutter wire-o..." | Re-trigger Greptile}

[chatgpt-codex-connector]

💡 Codex Review

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Reviewed commit: cff325d6d6

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[stamphog]

Note

🤖 stamphog reviewed cff325d6d6393c050119b4a8bd66a1d6f8e35a45 — verdict: REFUSED

Codex flagged an unresolved, substantive concern that this cutoff can cause existing legacy Flutter issues to lose their legacy fingerprint and split into new issues after resolution reshapes frames — the diff doesn't address it.

• Author wrote 100% of the modified lines and has 15 merged PRs in these paths (familiarity STRONG).
• chatgpt-codex-connector[bot] reviewed the current head.
• Unresolved inline comment from @chatgpt-codex-connector on rust/cymbal/src/modes/processing/normalization.rs: raises a real grouping/data-correctness concern (legacy fingerprint reconstruction breaking for pre-cutoff Flutter issues) that the diff does not address.

Gate mechanics and policy version

Gate		Result
prerequisites	✓	all clear
deny-list	✓	no deny categories matched
size	✓	10L, 1F substantive — within ceiling
tier	✓	T1-agent / T1a-trivial (10L, 1F, single-area, feat)
stamphog 2.0.0b3		.stamphog/policy.yml @ 8fd209c · reviewed head cff325d

[deployment-status-posthog]

Deploy status

Environment	Status	Deployed At	Workflow
dev	✅ Deployed	2026-07-23 17:10 UTC	Run
prod-us	✅ Deployed	2026-07-23 17:30 UTC	Run
prod-eu	✅ Deployed	2026-07-23 17:31 UTC	Run