Summary

Three Hands-page UX improvements, one PR.

#6150 — Enlarge the HAND.toml view

The manifest viewer (TomlViewer) was capped at a 3xl modal with a 65vh code pane, which is cramped for a dense manifest.
It now opens at 7xl with a 78vh scrollable body — near-fullscreen while still letting the centred modal manage its own 90vh cap.
Responsive and dark-mode behaviour is unchanged (same Modal shell, same theme tokens).

#6151 — Edit a hand agent's system prompt (with restore-default)

A new "Agent" tab on the hand detail panel lets you edit each role's system prompt in a textarea and save it.
A one-click "Restore default" (一键恢复默认) control resets the draft to the value shipped in the hand's HAND.toml.

#6152 — Edit a hand agent's tools (with restore-default)

The same tab edits the agent's tool allowlist (capabilities.tools): add a tool by name, remove an existing chip, then save.
"Restore default" resets the list to the HAND.toml baseline.

How it works

The editor seeds from the live agent config and writes through endpoints that already exist:

• System prompt: read via GET /api/agents/{id} (system_prompt), saved via PATCH /api/agents/{id} (usePatchAgent).
• Tools: read via GET /api/agents/{id}/tools (capabilities_tools), saved via PUT /api/agents/{id}/tools (useUpdateAgentTools).
• Restore-default target: the parsed HAND.toml values, newly exposed per-agent on GET /api/hands/{id}.

Editing is gated on the hand being active, because a live agent_id only exists for an active instance — the inactive state shows a "activate first" hint, mirroring the existing settings editor.
The manifest baseline on GET /api/hands/{id} is an honest reset target: the per-agent edit endpoints write the live AgentRegistry / agent.toml, never HAND.toml, so the default is never destroyed.

Backend change

One read-only addition: get_hand (crates/librefang-api/src/routes/skills/hands.rs) now emits system_prompt and capabilities_tools for each entry in the agents array, straight from the parsed manifest.
No new write endpoint was needed — the existing per-agent config endpoints already cover system prompt and tools.

Data-layer compliance

• All API access goes through hooks in src/lib/queries/ and src/lib/mutations/ (useAgentDetail, useAgentTools, usePatchAgent, useUpdateAgentTools); no inline fetch/api.* in the page.
• Query keys use the existing agentKeys factories; no inline key arrays.
• Mutation invalidation lives in the shared hooks (they already invalidate agentKeys.detail / agentKeys.tools).
• i18n keys added to all three locale files (en.json, zh.json, uk.json); no hardcoded user-visible strings.
• Tailwind + dark mode via theme tokens, lucide-react icons, motion/react tab transitions (reused from the existing tab system), TypeScript strict (no any).

Verification

Dashboard (crates/librefang-api/dashboard):

• pnpm install --frozen-lockfile — clean.
• pnpm typecheck — green.
• pnpm lint — 0 errors (only pre-existing baseline warnings; none from HandsPage.tsx source I added).
• pnpm test --run — 80 files, 794 tests passed.
• pnpm build — succeeds.

Rust (via the sanctioned Dockerfile.rust-dev image, per-worktree target volume — no host target/ contention):

• cargo check --workspace --lib — clean.
• cargo clippy -p librefang-api --all-targets -- -D warnings — clean.
• cargo test -p librefang-api --test hands_routes_integration — 29 passed, including the new get_hand_agents_expose_system_prompt_and_tools.
• cargo fmt -- --check on the changed Rust files — clean.

Maintainer notes

• The "Agent" tab edits a hand role's live agent via the standalone agent-config endpoints (PATCH /api/agents/{id}, PUT /api/agents/{id}/tools), which persist to the agent's agent.toml + DB. This is the same surface the Agents page already uses on hand-role agents. It does not rewrite HAND.toml; the manifest stays the source of "default", which is exactly what makes restore-default honest. I deliberately did not add a HAND.toml-rewriting endpoint (it would need format-preserving manifest surgery and a manifest-override merge layer in librefang-hands/librefang-kernel) — out of scope and unnecessary for the requested behaviour.
• There is a richer, hand-native override path (PATCH/DELETE /api/agents/{id}/hand-runtime-config → HandAgentRuntimeOverride, persisted to hand_state.json, reset-on-DELETE) that currently covers model/provider/tokens/temperature/web-search but not system prompt or tools. Extending it to carry those two fields would let restore-default route through a single DELETE and keep the override in hand_state.json instead of agent.toml. That is a cross-crate change (librefang-hands struct + merge, librefang-kernel apply, the route); happy to do it as a follow-up if you'd prefer that surface over the standalone agent-config endpoints used here.

Closes #6150
Closes #6151
Closes #6152