Lazy-load the boards, studio and the other optional modules a small forge never uses #12373

This moves the terminal server and the boards' boot-time modules to dynamic imports in src/main.ts. Boards and studio are still loaded at boot, because the HTTP routes import their pages statically. The bun test runs I did were test/boot-lazy.test.ts plus boot-no-stall and boot-idle-children (8 pass), tsc and scripts/gate.ts.

What I measured. The boot's static import graph, read with Bun's import scanner, had about 2,890 modules. 267 of them were the terminal UI, 80 were web/studio, and 18 were boards/.

What changed

• tui/ssh.ts is imported only when FORGE_SSH_PORT is above 0. A hosted forge or a read-only standby no longer loads its 267 modules.
• boards/sampler.ts, boards/memory.ts, web/pages/boards-view.ts (the warm-up) and actions/boards.ts (the starting boards) are imported dynamically. They load after the listener is up and are no longer static imports of main.ts. The shutdown path waits on the sampler handles.
• test/boot-lazy.test.ts has 6 tests:

- the static graph from main.ts contains no src/tui/ module; - tui/ssh.ts is reached only dynamically; - main.ts has no static import of the four boards modules and imports each dynamically.

• Without the main.ts change the file fails; I ran it only with main.ts stashed and the new test file still present (all 6 failed).

What I chose not to do

• Boards and studio at boot: they stay in the graph (about 80 studio modules and 11 boards modules). http/api.ts, web/pages/site.ts and http/server.ts import the pages statically, so loading them lazily means changing the route registry. That is a separate change.
• Samplers: they still run at boot. Importing them dynamically only moves the load off the critical path, because the samplers always run. The test comment says this.
• Other optional modules: I only looked at boards, studio and the terminal. A follow-up issue for lazy route modules would be the next step.

Where it failed: the sandbox denied network access to forge.test hosts during the boot tests, but they passed.

To try it: bun test test/boot-lazy.test.ts.

Boot now imports the terminal, the boards' samplers and the warm-ups when they are first used, not at load. The check had failed only the gate rule that limits comment lines to 100 columns. I rewrapped three comment lines, in src/main.ts and test/boot-lazy.test.ts, and the code is unchanged.

bun scripts/gate.ts and bun x tsc --noEmit are clean, and test/boot-lazy.test.ts passes (6 tests). I did not run the wider fast tier here; the forge's check will run it on this push. The gate only saw the rewrap once it was committed, so the earlier gate runs on the uncommitted edit still showed the old errors.

To try it, open / on the preview (https://lab--12373--forge-trevato-apps.open-platform.sh).

This pull now only makes the terminal (tui/ssh.ts) lazy at boot. The boards and studio parts are dropped, and the title no longer describes the pull — it needs narrowing to the terminal. No timings were measured.

What changed

• Terminal import: src/main.ts imports tui/ssh.ts only when sshPort > 0, so a forge run with FORGE_SSH_PORT=0, as hosted forges are, never loads the terminal modules. A failed load is logged with app.log.warn("ssh is off: the terminal failed to load", …) and boot carries on without the terminal.
• Boards: the dynamic imports of sampler.ts, memory.ts, boards-view.ts and actions/boards.ts are reverted to static. You were right that the routes already load them, so the dynamic imports saved nothing. That also removes the two promise-wrapped samplers with no rejection handler, and the bare .catch(() => {}) on warmBoards.
• Tests: the four syntax-only boards tests are removed. test/boot-lazy.test.ts keeps two tests that read the real static import graph from main.ts. They check that no src/tui/* module is in it and that tui/ssh.ts is reached only by a dynamic import. I ran those two tests, bun x tsc --noEmit and bun scripts/gate.ts; the gate printed nothing I could read as a failure, but I did not check its exit code. I did not run bun scripts/design-lint.ts (nothing under src/web/ changed) or the forge's full check.

What I chose not to do

• Lazy route registry: making the registry lazy for boards and studio is the larger change the issue asks for. It touches http/api.ts, web/pages/site.ts and http/server.ts, so it should be its own pull. I did not start it here.
• Direction and measurement: I have no evidence this pull serves the owner's pipeline-first list (#6534, #6611, #5276, #3316). It is a small boot-time saving, and you can defer it. The 4.6 s first request on the preview is a cold start I have not profiled, and I have not measured boot or first-response time before and after. Treat this pull as unproven on speed until someone does.

To try

• Run FORGE_SSH_PORT=0 bun run src/main.ts. / answers and the terminal modules are not loaded.
• Run bun test test/boot-lazy.test.ts.

The gate failure is fixed and pushed. The header comment in test/boot-lazy.test.ts ran 112 columns, and I rewrapped it to under 100. Only that comment changed, so nothing else in the pull is different.

Checks I ran before pushing:

• Gate: bun scripts/gate.ts passes.
• Type check: bun x tsc --noEmit is clean.
• Test: test/boot-lazy.test.ts passes (2 tests).

The gate kept reporting the old line after my edit and only went green once the change was committed. It appears to read committed content rather than the working tree.

The pull still does what it did before. The boot imports the terminal UI on first use instead of at load, and a test checks the static import graph for it. The boards stay static, and a failed terminal load is logged.