docs(security): document EndConversation as the sanctioned termination path (2.1.214)

[elhoim]

Problem

DOCUMENTATION/Security/README.md documents the full security model — L1 constitutional rule, L2 native deny-list, L3 safety hook — but says nothing about how a session is ended. EndConversation appears nowhere in the documentation tree.

Why it matters

Claude Code 2.1.214 added the EndConversation tool, giving Claude a sanctioned way to end sessions with abusive users or persistent jailbreak attempts. This matches claude.ai behavior since 2025.

Leaving it undocumented has two costs:

• The capability exists but is undiscoverable, so the fallback is an ad-hoc refusal loop — worse for everyone involved.
• The tool ships deferred: only its name is in context at session start, so calling it requires loading the schema first. Someone who learns it exists still can't invoke it without knowing that.

There is also a real risk in the other direction. Ending a conversation and declining a request are different actions with different thresholds, and an undocumented tool invites over-application.

Fix

Adds a ### Session termination — EndConversation subsection under L1 covering:

• Use it for — sustained abuse directed at the assistant, persistent jailbreak attempts after the boundary has been stated.
• Do NOT use it for — ordinary disagreement, a request declined on other grounds, a task that merely touches a sensitive topic.
• The ToolSearch("select:EndConversation") load line, since it ships deferred.

Documentation-only change.

Affected versions

Introduced in Claude Code 2.1.214.

Reference: https://www.anthropic.com/research/end-subset-conversations

[danielmiessler]

Ported with credit — a new "Session termination — EndConversation" subsection under L1 with the use/don't-use split and the deferred-load line. The over-application risk you flagged is why the thresholds are stated explicitly rather than just naming the tool. (Closing rather than merging — generated-repo doctrine; the port ships in the next release.)