refactor(cli): fold gateway into call, drop the local-command machinery

[Miyamura80]

Summary

Collapses sealg to its intended thin shape: a client to the SealGate gateway, nothing more. sealg call <tool> now is the gateway tools/call (previously it ran a local demo-command registry, and the gateway call lived under a separate gw-call). Connection overrides like pointing at a local instance are a flag, not a subcommand. All the Rust-CLI template's onboarding/scaffolding/stub machinery is deleted.

Final command surface: doctor | list | call.

Changes

• call is the gateway call: sealg call <tool> [--args '<json>'] [--gateway-url <url>] → MCP tools/call. Pretty-prints the result; exits 6 on an MCP isError: true result, 1 on transport failure. gw-call removed.
• --gateway-url: overrides the gateway base URL (default $SEALGATE_URL, else localhost) for local/other instances. Implemented as GatewayConfig::from_env_with_url_override (trims trailing /, ignores blank and degenerate all-slash values; unit-tested). No other flags — API key / secret stay env-only.
• list gains the same --gateway-url (keeps --json).
• Deleted the local-command machinery (dead once call is the gateway): the engine::commands module (Command/Expose/CommandRegistry + all six demo commands), scenario.rs + scenario types, probes.rs, context.rs/traits.rs/platform.rs, and the scaffold/new command. The probe and run-scenario subcommands go with them.
• Deleted init (the template "onboard this project" wizard) and its module, plus 7 dependencies only it used.
• Deleted the mcp stub subcommand (inherited template scaffolding that only printed a not-implemented notice). The MCP protocol client in engine::gateway is untouched — that's how list/call talk to the gateway.
• Kept: doctor (local env facts).
• Docs: root/cli/engine READMEs, CLAUDE.md, and the Makefile updated to match; the architecture diagram regenerated with aligned boxes.

Net across the branch: roughly −4800 lines — almost entirely deletion of template scaffolding.

Testing

• cargo build --workspace — clean
• cargo clippy --workspace --all-targets -- -D warnings — 0 warnings
• cargo test --workspace — 0 failed (gateway tests + url_override tests included)
• cargo fmt --all --check — clean
• cargo build --release -p sealg; sealg --help lists exactly doctor, list, call; sealg call --help shows <tool> [--args] [--gateway-url]

The gateway transport itself was verified end-to-end against a live local gateway in #15; this PR only changes how it's surfaced and deletes dead code.

Related Issues

Follow-up to #15. Tracked by the multi-interface design doc in edison-watch/edison-watch.

Notes / out of scope

• A couple of engine Cargo.toml deps (e.g. inventory, schemars) are now unused; not a build/clippy/deny failure, left for a separate dependency trim.
• HUMANS_SHOULD_TEST.md and the .claude/skills/{update-backend,onboarding} docs still describe parts of the old template workflow (a serve HTTP API); rewriting those fully is separate, larger work.

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[cubic-dev-ai]

All reported issues were addressed across 27 files

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[cubic-dev-ai]

1 issue found across 27 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="README.md">

<violation number="1" location="README.md:51">
P3: The rewritten architecture diagram is misaligned: the first box's content lines (e.g. `sealg list ...`) are one character narrower than the box's own border, and the vertical connectors (`engine::gateway`, `HTTPS`) sit one column right of the `┬`/`▼` glyphs they join, with the two boxes having different widths. Rendered in markdown the diagram looks broken. Pad each content line of the first box by one space so its right `│` lines up with the border's `┐`/`┘`, and shift the `│` connectors left by one column so they line up under the `┬` glyphs.</violation>
</file>

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[cubic-dev-ai]

1 issue found and verified against the latest diff

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="crates/cli/src/main.rs">

<violation number="1" location="crates/cli/src/main.rs:33">
P1: The new command enum drops `Init`, so `sealg init` now fails as an unknown subcommand even though this PR promises to retain it. Restore the init module and variant, or update the CLI contract and documentation consistently.</violation>
</file>

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[cubic-dev-ai]

1 issue found across 36 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="crates/engine/src/gateway/config.rs">

<violation number="1" location="crates/engine/src/gateway/config.rs:73">
P3: An override that trims down to an empty string silently produces an empty `base_url`. `u.trim()` on `/`, `///`, or `/?x` is non-empty, and `trim_end_matches('/')` then yields `""`, so `cfg.base_url` becomes empty and `mcp_url()` becomes `/mcp/` instead of falling back to the env/default. Guard the trimmed value with a non-empty check before assigning, so a degenerate override is ignored like a blank one.</violation>
</file>

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