fix(skills): render inline shell in skill_view

[teknium1]

Salvage of #15306 by @helix4u — cherry-picked onto current main with one follow-up fix.

Summary

Skills loaded through the skill_view tool now honor skills.inline_shell and skills.template_vars the same way the slash/preload path already did. Previously !\cmd`snippets and${HERMES_SKILL_DIR}tokens came back raw fromskill_view, and the model had to separately call terminal` to realize the shell value.

Reported by a user in Discord — config had skills.inline_shell: true but !\date -u +%Y-%m-%d`` reached the model unrendered.

Changes

• agent/skill_preprocessing.py (new): shared preprocess_skill_content() / expand_inline_shell() / substitute_template_vars() / load_skills_config()
• agent/skill_commands.py: imports helpers from the shared module; slash/preload path calls skill_view(preprocess=False) and renders the skill message itself as before
• tools/skills_tool.py: skill_view() applies preprocessing by default on both the main skill path and _serve_plugin_skill; new preprocess: bool = True parameter for internal callers
• Follow-up on top of @helix4u's commit: dropped the raw_content field from the skill_view JSON response. It went to the model verbatim and duplicated the SKILL.md body on every tool call; the slash/preload caller falls back to content when raw_content is absent (and passes preprocess=False anyway), so nothing downstream needs it.

Validation

E2E with the reporter's exact skill + config (inline_shell: true):

• Before: content ends in Current date: !\date -u +%Y-%m-%d`` (literal)
• After: content ends in Current date: 2026-04-24 (rendered)
• raw_content not present in response (no duplicated payload)

Targeted tests: scripts/run_tests.sh tests/tools/test_skills_tool.py tests/agent/test_skill_commands.py → 114/114 passed.

Closes #15306.

[github-actions]

⚠️ npm lockfile hash out of date

Checked against commit b6b088d (PR head at check time).

The hash = "sha256-..." line in these nix files no longer matches the committed package-lock.json:

• nix/web.nix:7 (.#web): sha256-TS/vrCHbdvXkPcAPxImKzAd2pdDCrKlgYZkXBMQ+TEg= → sha256-4Z8KQ69QhO83X6zff+5urWBv6MME686MhTTMdwSl65o= — lockfile: web/package-lock.json

Apply the fix

• Apply lockfile fix — tick to push a commit with the correct hashes to this PR branch
• Or run the Nix Lockfile Fix workflow manually (pass PR #15376)
• Or locally: nix run .#fix-lockfiles -- --apply and commit the diff