[SizzleUnrlsd]

Release 0.21.0: the three advisory mechanisms of #195, #197 and #194, which the Enterprise curation waits on.

Advisories

• An argument condition may carry present: true: the argument being passed at all, whatever its value, is the condition (Advisory condition on an argument being passed, whatever its value #195).
• A curated entry point may declare suffixes, matched against the tail of a derived symbol of the project's own modules, for receivers the engine cannot type (Match curated entry points by suffix for receivers the engine cannot type #197); ModelTable.sink now composes an exact sink with the matching suffix sinks instead of shadowing.
• A sequence condition relates two calls on one receiver: met by a dominating satisfied prior call, contradicted only when the followed receiver shows no call that could satisfy it, the entry call itself included (Relate two calls on one receiver for advisories whose flaw spans a call sequence #194).

Plugins

• CallSite.prior_calls and PriorCall; the cache format becomes 13.

Changes

• CHANGELOG.md: Unreleased becomes 0.21.0 (2026-09-30).
• pyproject.toml, src/coretrace_python/__init__.py: 0.21.0, checked equal.
• docs/usage.md: the three version examples.
• tests/test_release.py: 0.20.0 becomes 0.21.0 on line 33 only, as authorized once feat: decide an argument condition on the argument being passed #199, feat: match curated entry points by suffix for untypeable receivers #200 and feat: relate two calls on one receiver for sequence advisory conditions #201 were merged.

Verification

tests/test_release.py, tests/test_docs.py, tests/test_packaging.py: 11 passed, 2 skipped in 0.73s. Full suite under Python 3.12, regression corpus excluded: 1642 passed, 2 skipped, 19 deselected in 70.61s (0:01:10). ruff check passes. The regression corpus ran green on the stacked branch of #201 (identical content to this main) and on main's CI.