docs(pointers): close open pointer findings in harness-ops #8008

Refs: #7293

Agent Brief

Type: Task
Summary: Close the upstream-pointer sweep's open medium and low findings in harness-ops.

Current behavior:
The sweep's light pass (#7293) left these findings open as of 2026-10-11/12:

• audit_performance.py subagent-limit comment: missing-pointer, sub-agents#concurrent-subagent-limit and #let-subagents-spawn-their-own-subagents; Windows shell comment: incomplete-record, troubleshoot-install
• audit-skill-visibility usage-counters: missing-pointer, claude-directory#cleaned-up-automatically
• plugins skill gotchas: drift, headless#start-faster-with-bare-mode
• known-performance-issues: drift and incomplete-record, desktop shared-configuration
• observability operator-setup-emission-privacy: incomplete-record, agent-sdk/observability#control-sensitive-data-in-exports

Desired behavior:
Each listed passage is re-checked against the live page (docs fetch scripts). A finding already fixed on main is left alone and noted in the PR body. Otherwise: drift is corrected to what the live page says now; a missing pointer gains a pointer record (exact anchor, as-of date, recheck trigger); an incomplete record gains its missing parts; a wrong-host citation names the canonical URL. Restated volatile specifics in skill bodies become pointers, not new copies.

Key interfaces:

• Pointer records: anchor, as-of date and recheck trigger beside each restated upstream fact.

Acceptance criteria:

• Each listed finding is either changed in the diff or named in the PR body as already fixed, with the live anchor it was checked against.
• Every pointer record the diff adds or completes carries an anchor, an as-of date and a recheck trigger.
• check-skill.sh passes on every skill whose files the diff touches. (skip if no skill file is touched)
• scripts/check-changelog-fragments.sh passes, with one changelog fragment for each plugin the diff touches. (skip for repository-root files)

Out of scope:

• High-severity findings (not in Light pointer pass: open medium and low pointer findings from the upstream-pointer sweep #7293).
• Files outside this group.
• Vendored upstream baselines (playbooks boris vendor/upstream-skill.md).

This was generated by AI during backlog shaping. Split from #7293; the owner approved filing it in an attended backlog-shaping session on 2026-10-18.