feat(line): inline-button approval prompts (Allow Once / Session / Always / Deny)

[wuwushi4]

Summary

LINE's dangerous-command approval today is text-only — the user has to type /approve, /approve session, /approve always, or /deny into the chat. Every other platform with a button UI (Telegram, Slack, Discord, Feishu, QQBot) renders four tappable buttons instead. This PR brings LINE up to parity using Template Buttons + postback dispatch.

Surfaced by a user in Taiwan running a private LINE OA who pointed out the friction: "在 LINE 上面如果遇到需要使用者允許的指令的話，會有點麻煩 … 之前 Telegram 聊天室窗中這會變成一個可以點按的按鈕，方便許多" (rough English: "approval prompts in LINE are clunky — Telegram makes them tappable buttons, much easier").

How it works

LineAdapter.send_exec_approval sends two LINE messages in one Push call:

1. Command preview — a plain text bubble carrying the command + reason. Separated because the Buttons template's text field caps at 160 chars, which is too tight for arbitrary shell commands.
2. Buttons template — four postback actions: ✅ Allow Once / ✅ Session / ✅ Always / ❌ Deny. Each carries postback data {\"action\": \"approve\", \"choice\": <...>, \"approval_id\": <int>}.

_handle_postback_event is refactored to dispatch on the action field — the existing slow-LLM show_response path is untouched (regression test included); a new approve branch routes the choice into tools.approval.resolve_gateway_approval(session_key, choice) — the same unblock primitive every other platform's button flow uses.

The _approval_state map (approval_id → session_key) mirrors Telegram's exactly, with pop-based discipline: a second tap on the same prompt is a safe no-op and gets an "already resolved" reply via the fresh postback reply token.

Trade-offs documented in the docstring

• Push, not Reply. Approval prompts fire mid-agent-turn, well after the inbound message's reply token has expired (~60s window). Each prompt costs one Push call against the LINE quota (200 free/month on the developer tier). In exchange the user gets a tappable UX, and the per-tap acknowledgement messages reuse the fresh postback reply token, so confirmations stay free.
• No message edit. LINE has no edit-message API, so we can't strike out the prompt and replace it with "✅ Approved by …" the way Telegram does. Instead we send a follow-up text bubble with the chosen label (✅ Approved once, ✅ Approved permanently, ❌ Denied, etc.).

Duck-typing contract

gateway/run.py:_approval_notify_sync does:

if getattr(type(_status_adapter), \"send_exec_approval\", None) is not None:
    # ... call it; on SendResult(success=False), log warning and fall through to text

So adding the method on the class is enough — no base-class change, no platform-registry change, no env or config knob. Adapters that fail to push will still degrade cleanly to the existing text path.

Tests

tests/gateway/test_line_approval_buttons.py — 23 tests, all passing.

• Builder: four actions, correct choice ordering (once → session → always → deny), action-label / altText / template-text caps respected, postback data well-formed JSON.
• send_exec_approval: pushes preview + buttons in one call, command and reason show in preview bubble, approval_id increments, session is recorded only after a successful send (failed Push leaves no dangling state), long commands are truncated, returns SendResult(success=False) when disconnected so the gateway can fall back to text.
• _handle_approval_postback: each of the four choices routes to resolve_gateway_approval with the right kwargs; double-tap is idempotent and surfaces a user-visible "already resolved" notice; unknown choice or non-int approval_id are silently ignored; confirmation reply uses the postback reply token; existing show_response postback path still works after the dispatch-on-action refactor.
• Class-level visibility: getattr(type(adapter), \"send_exec_approval\", None) is not None — guards the duck-typing probe in gateway/run.py.

The existing tests/gateway/test_line_plugin.py (73 tests) still passes unchanged.

Test plan

• Unit suite (23 new + 73 existing LINE tests pass)
• Live verified on a real LINE Official Account: prompt appeared, tapping Always produced LINE button resolved 1 approval(s) for session agent:main:line:dm:Uxxxx (choice=always) and the agent then ran the gated command end-to-end.
• Live verified in group / room (untested — same code path, same fix applies)

Note on overlap with #23569

This branch is based on a clean origin/main and does not include the create_source → build_source typo fix from #23569. Without that fix, inbound LINE messages don't dispatch at all, so this feature can't be triggered end-to-end on plain main. Suggested merge order: land #23569 first (1-line fix), then this PR rebases cleanly on top.

🤖 Generated with Claude Code

[wuwushi4]

Superseded by #29053.

Rebased onto v2026.5.16 with a clean scope — the new PR contains only the LINE inline-button approval feature (plugins/platforms/line/adapter.py + new test file). The accidental extra commits (browser supervisor, skill manager, run agent prompt) that landed here after my local rebase are dropped — they are personal config tweaks, not relevant to upstream.

Same author, same approach, same tests. Please review #29053 instead. Thanks!