chore: bump C++ server SDK to 3.14.0 and Redis source to 2.4.2

[devin-ai-integration]

Summary

Moves the examples and CI to the latest C++ Server-side SDK release (3.14.0) and Redis Source release (2.4.2), both published 2026-09-28. This follows the same pattern as #114.

• examples/hello-{debian,haproxy,nginx}/Dockerfile: ARG CPP_SDK_VERSION=3.13.1 → 3.14.0
• .github/variables/cpp-sdk-versions.env: sdk=3.13.1 → 3.14.0, redis_source=2.4.1 → 2.4.2
• test-redis.lua: testVariationDetailWithRedisSource now expects errorKind = "FLAG_NOT_FOUND" instead of "CLIENT_NOT_READY". This is required by the bump: cpp-sdks#508 (in 3.14.0) makes lazy-load mode always report initialized. As a result, an unreachable store now returns the default with FLAG_NOT_FOUND rather than CLIENT_NOT_READY. This is an intentional upstream change, documented under "Behavioral change" in that PR.
• The README minimum-version table (3.9.0 / 2.1.19) stays as it is. It lists the minimum supported versions, and 3.14.0 doesn't require raising them. Lua SDK C code, rockspecs, base images, boost and Actions pins are also unchanged.

Implementation details

Why these are exact pins: Docker ARGs and the CI env file are build inputs, not package-manager constraints, so there is no range syntax. The only way to track the latest release is to bump the pin within major 3 (and within major 2 for the Redis source).

What changed upstream in 3.14.0: FDv2 streaming synchronizer for the client SDK, two server-side bug fixes (lazy-load evaluations without $inited per #508, and keyed tombstones are now read as deleted), and internal bumps to cpp-internal 0.15.0 and cpp-sse-client 0.8.0. Redis Source 2.4.2 only bumps its cpp-server dependency to 3.14.0. The C binding headers have no API changes between 3.13.1 and 3.14.0.

Test change: On the first CI run of this PR, the 4 linux-build (*, launchdarkly-server-sdk-redis-…) jobs failed with expected CLIENT_NOT_READY, actual FLAG_NOT_FOUND in testVariationDetailWithRedisSource. The test points the client at an unreachable redis://localhost:1234, which is exactly the case #508 changed. Note that the rockspec doesn't constrain the C++ SDK version, so anyone who builds the Lua SDK against 3.14.0 already gets this behavior. Only the test expectation changes here.

Deprecations: None in the C binding headers at 3.14.0. The examples only use ld.clientInit, ld.makeContext and client:boolVariation. The deprecated makeUser is not used.

Local testing (Linux VM, Docker):

• I built all three example images with the bumped Dockerfiles. Base images were swapped to mirror.gcr.io/library/... in uncommitted copies to get around docker.io rate limits. Each image was run with the hello-app server key and LAUNCHDARKLY_FLAG_KEY=hello-boolean:
  • hello-debian (C++ SDK built from source at 3.14.0): The hello-boolean feature flag evaluates to true.
  • hello-haproxy (3.14.0 linux-gcc-x64-dynamic.zip release artifact): <p>The hello-boolean feature flag evaluates to true.</p>
  • hello-nginx (OpenResty 1.21.4.1, built from source at 3.14.0): <p>The hello-boolean feature flag evaluates to true.</p>
• luarocks test launchdarkly-server-sdk-redis-2.2.0-0.rockspec (Lua 5.3, Redis Source linux-gcc-x64-dynamic.zip):
  • main's test file vs 2.4.1 / 3.13.1: 4/4 pass (baseline)
  • main's test file vs 2.4.2 / 3.14.0: 3/4, reproducing the CI failure
  • this branch vs 2.4.2 / 3.14.0: 4/4 pass

Link to Devin session: https://app.devin.ai/sessions/568e1aed51484d00a044173ce3f061f6
Open in Devin Desktop: https://app.devin.ai/desktop/session/568e1aed51484d00a044173ce3f061f6?variant=devin

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Note

Overview
Bumps pinned C++ Server SDK to 3.14.0 and Redis source to 2.4.2 across CI (.github/variables/cpp-sdk-versions.env) and the hello debian, haproxy, and nginx example Dockerfiles (CPP_SDK_VERSION).

Updates test-redis.lua so testVariationDetailWithRedisSource expects FLAG_NOT_FOUND instead of CLIENT_NOT_READY when evaluating against an unreachable Redis URL in lazy-load mode—matching upstream 3.14.0 behavior (lazy-load clients report initialized; missing flags surface as not found rather than client-not-ready).

^{Reviewed by Cursor Bugbot for commit 993c3f5. Bugbot is set up for automated code reviews on this repo. Configure here.}

[devin-ai-integration]

I'll fix CI failures and address comments from users with write access. I'll skip comments containing "(aside)".

• Disable automatic comment, CI, and merge conflict monitoring

[devin-ai-integration]

@cursor review

[devin-ai-integration]

@cursor review