LAB-446: per-backend TTL inspection note (Python File full, Memcached refresh-only)

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LAB-446: per-backend TTL inspection note (Python)

Companion to cachekit-io/cachekit-py#230 (LAB-446). Keeps the cross-SDK matrix honest now that Python's per-backend TTL-inspection support has changed.

• Python File backend now implements full TTL inspection/refresh (TTLInspectableBackend).
• Python Memcached implements refresh_ttl (via touch) only, not get_ttl — the Memcached protocol has no command to read a key's remaining TTL and pymemcache's HashClient exposes no meta protocol — so it is not a full TTLInspectableBackend and refresh_ttl_on_get does not apply to it.

Adds a per-backend note under the TTL management row (the row itself was already SDK-level ✅ for Python) and refreshes the last-updated line. The note also records that rs (LAB-429) and ts (LAB-430) must match this split (refresh-only Memcached, full File) when those backends land there.

No spec / wire-format / encryption changes — documentation only.

Summary by CodeRabbit

• Documentation
  • Updated the SDK feature matrix with the latest revision date.
  • Added guidance on inspecting and refreshing file-backend TTLs in Python.
  • Documented Memcached TTL refresh behaviour, including its refresh-only limitation.
  • Clarified Python TTL management support and when automatic TTL refresh applies.
  • Added references for tracking equivalent capabilities across other SDKs.

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Review details

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Run ID: 8fa2c7ef-a3ac-49fe-886c-b24895e4446e

📥 Commits

Reviewing files that changed from the base of the PR and between c4061b1 and 958f5b5.

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• sdk-feature-matrix.md

Walkthrough

The SDK feature matrix now reflects the 2026-07-21 update and documents Python file backend TTL inspection/refresh alongside Memcached refresh_ttl touch behaviour and related cross-SDK tracking.

Changes

TTL management documentation

Layer / File(s)	Summary
Backend TTL capability notes sdk-feature-matrix.md	Updates the date banner, Python TTL management status, supported backends, Memcached refresh-only behaviour, and Rust/TypeScript parity references.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Possibly related PRs

• cachekit-io/protocol#10: Updates the same Reliability Features and TTL management documentation.
• cachekit-io/protocol#23: Adds related backend capability and TTL parity clarifications.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title is concise and accurately summarises the main documentation change about backend-specific TTL inspection and Memcached refresh-only behaviour.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch lab-446-ttl-inspection-matrix

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Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@sdk-feature-matrix.md`:
- Around line 94-95: Remove the blank line after the lock ID transport
blockquote in sdk-feature-matrix.md, or prefix that line with “>”, so the
following TTL note remains within one continuous blockquote and satisfies
Markdownlint MD028.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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Configuration used: Path: .coderabbit.yaml

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📥 Commits

Reviewing files that changed from the base of the PR and between 891d1bf and c4061b1.

📒 Files selected for processing (1)

• sdk-feature-matrix.md