fix(agent): gate coding-posture skill-index demotion behind the opt-in focus mode

[teknium1]

Summary

The coding posture's skill-index demotion now only applies under the opt-in focus mode — the default auto posture (and on) never touch the skill index.

#43316/#44342 demoted non-coding skill categories to names-only under the default posture, silently changing the prompt's skill index for every user sitting in a git repo. Index changes are now opt-in, matching the gating contract of the focus toolset collapse. Focus semantics are unchanged: demoted, never hidden; deny-list keeps coding-adjacent and unknown/custom categories at full entries.

Changes

• agent/coding_context.py: RuntimeMode.compact_skill_categories() returns empty unless config_mode == "focus"; module/profile docs updated.
• agent/system_prompt.py, hermes_cli/config.py: comments updated to match.
• tests/agent/test_coding_context.py: asserts auto/on demote nothing, focus demotes the deny list.

Validation

	Before	After
auto / on skill index	non-coding categories names-only	untouched
focus skill index	names-only demotion	names-only demotion (unchanged)
test_coding_context + prompt_builder + system_prompt	—	183 passed

E2E (real imports, temp HERMES_HOME, real git repo): auto/on → frozenset(); focus → deny list active, autonomous-ai-agents/games never demoted; messaging platforms never demote even on focus.

Infographic

[github-actions]

🔎 Lint report: fix/skill-compacting-focus-gate vs origin/main

ruff

Total: 0 on HEAD, 0 on base (➖ 0)

🆕 New issues: none

✅ Fixed issues: none

Unchanged: 0 pre-existing issues carried over.

ty (type checker)

Total: 10719 on HEAD, 10719 on base (➖ 0)

🆕 New issues: none

✅ Fixed issues: none

Unchanged: 5611 pre-existing issues carried over.

Diagnostics are surfaced as warnings — this check never fails the build.