### What problem does this PR solve?
Closes#16414.
The **Crawler** agent tool (`agent/tools/crawler.py`) was never ported
to the modern `ToolBase`/`_invoke` interface during the agent module
redesign, so it was broken in three independent ways:
1. **Crashed on construction.** `CrawlerParam` extends `ToolParamBase`,
whose `__init__` reads `self.meta["parameters"]`, but `CrawlerParam`
defined no `meta`. Constructing it raised `AttributeError:
'CrawlerParam' object has no attribute 'meta'`. Because
`agent/canvas.py` instantiates `component_class(component_name +
"Param")()` while loading a canvas, **any agent containing a Crawler
node failed to load.**
2. **`_invoke` missing.** It extends `ToolBase` (whose `invoke()`
dispatches to `self._invoke`) but only implemented the legacy `_run`, so
`_invoke` resolved to `ComponentBase._invoke` → `NotImplementedError`.
3. **`be_output` removed.** `_run` called `Crawler.be_output(...)`,
which no longer exists on the base classes.
### Type of change
- [x] Bug Fix (non-breaking change which fixes an issue)
### Changes
- Add a `ToolMeta` to `CrawlerParam` (defined before
`super().__init__()`, matching every other ported tool such as
`ArXivParam`/`TavilyExtractParam`) advertising a required `query`
parameter — the URL to crawl, default `{sys.query}`, consistent with the
`{sys.query}` convention shared by the other tools.
- Replace the legacy `_run`/`be_output` with `_invoke`/`set_output`,
writing the extracted page content to `formalized_content` (errors
surfaced via `_ERROR`), consistent with the other tools.
- Preserve the existing SSRF guard (`assert_url_is_safe` +
`pin_dns_global`).
- Add regression tests
(`test/unit_test/agent/component/test_crawler.py`) covering param
construction, validation, and the tool descriptor.
Same class of defect as #16329 (DeepL). Backend-only; no frontend
changes.
---------
Co-authored-by: Zhichang Yu <yuzhichang@gmail.com>
Replaces the Python agent canvas runtime with a Go implementation that
runs inside `cmd/server_main`.
The canvas compiles into an eino Workflow that pauses on wait-for-user
via native Interrupt/Resume (no sentinel flag) and resumes from a
Redis-backed CheckPointStore.
All 21 Python agent components and ~35 tools are ported with functional
parity.
Sandbox providers now read their JSON config from the admin-panel
system_settings table with env fallback.
234 files / +35,413 / -6,111. All Go files are gofmt-clean (CI gate
added); drops the v2 DSL E2E step and the gap-analysis plan (both
redundant after the port ships).
## Type of change
- [x] Refactoring
- [x] New feature
- [x] Bug fix
🤖 Generated with [Claude Code](https://claude.com/claude-code)
---------
Co-authored-by: Claude <noreply@anthropic.com>
