Cherry-pick of the 3 value commits from #11323 (by @RaviTharuma), dropping 17 already-merged rebase-baggage commits. Validated in a combined-batch worktree off release/v3.8.51 tip:
- typecheck:core, file-size, changelog-integrity, complexity, cognitive-complexity gates — all OK
- Focused tests, isolated re-run flake-free: accountSemaphore.test.ts 11/11, chatcore-hierarchical-admission.test.ts 2/2, resilience-settings-provider-quota-overrides.test.ts 12/12, i18n-vi-completeness.test.ts 5/5
- lint clean once isolated from the unrelated ESLint-10 suppressions regression carried by a separate PR in the batch
Closes#7778. Full credit to @RaviTharuma for the design and implementation.
Merged after conflict resolution in modelMetadataRegistry.ts: the tip's effortTiers chain (declared efforts → declared tiers → undefined-if-thinking-declared → codex extension) now carries this PR's GLM guard as the final-fallback override — GLM-family models without a provider-declared contract get the authoritative empty tier list instead of generic OpenAI tiers. GLM/ZCode suites 40/40 on the resolved branch. Closes#10962. Thank you @xz-dev!
