Enforce automation length caps at the CLI boundary, not on stored rows

[SawyerHood]

What was wrong

bb automation create and bb automation update built the agent and script execution payloads from argv and handed them straight to the service, skipping the request-side Zod length caps that the automations_create/automations_update RPC routes apply. An over-cap --prompt (8,039 chars against the 8,000 cap) was therefore persisted, and the too_big error the user saw came from re-parsing the stored row for the response. Because that same capped schema (automationAgentExecutionSchema) was also used to parse stored rows, every later list, show, and repairing update for the project failed with the same too_big issue, and list took the healthy automations in the project down with it. Report: https://get-bb.github.io/reports/issues/2166.html

What changed

The length caps were request policy applied in the wrong place. The same Zod schemas that parse incoming create/update input also parse the stored execution and trigger_config columns, so an over-cap value that got past the CLI was written and then made the row unreadable on every subsequent read.

• Split request policy from the stored shape, on both columns. The stored automationAgentExecutionSchema, automationScriptExecutionSchema, and automationScheduleTriggerSchema no longer carry the prompt, script, scriptFile, cron, or timezone caps. New *RequestSchema variants (automationAgentExecutionRequestSchema, automationScriptRequestSchema, automationTriggerRequestSchema) add the caps back and are what createAutomationInputSchema / updateAutomationInputSchema compose, so the RPC routes still reject over-cap input before any write. A row that already exceeds a cap now stays readable by list/show and repairable by update.
• Enforce the same policy at the CLI argv boundary. bb automation create/update builds its execution and trigger from argv and calls the service directly, bypassing the route schemas. buildExecution, buildAgentExecutionUpdate, and buildTrigger now parse with those request schemas, so an over-cap --prompt, --script, or --cron is rejected before anything is persisted, and the CLI and the RPC route agree on one policy.
• Make service.list skip a malformed row with a warning, like overview already did, so one bad row cannot fail the whole project listing.

The one-shot trigger variant is unchanged (it carries no string). The timezone cap is unreachable through the CLI in practice — no valid IANA name approaches 100 characters — so it is asserted at the schema level only.

How you verified

Twelve regression tests across two blocks in plugins/automations/src/automations.test.ts; each behavior test was run against the pre-fix source and fails there (6 execution-cap tests, 5 of 6 trigger-cap tests — the sixth is a guard asserting the over-cap cron is itself valid, so the others cannot degrade into "invalid cron rejected").

• pnpm exec turbo run test --filter=bb-plugin-automations --force — 5 files, 78 passed.
• pnpm exec turbo run build typecheck lint (repo-wide) — 92/92 tasks.
• node scripts/check-provider-literal-ratchet.mjs --base origin/main — 18 references across 8 core files, all allowlisted.
• Live against an isolated scripts/bb-dev-app instance: an over-cap --prompt (8039 chars) and an over-cap --cron (177 chars, valid 5-field expression) each exit 1 with too_big and write no row; an over-cap --cron on update leaves the stored trigger byte-identical; a row seeded with a 177-char cron is listed, shown, renamed, paused, resumed, and repaired, all exit 0; the sweep advances that row and claims a scheduled run instead of logging invalid stored configuration every tick.
• Live plugin-RPC HTTP calls confirm the routes still reject pre-write: automations_create returns HTTP 400 invalid_input with path: ["trigger","cron"] and with path: ["execution","prompt"], and the automations table row count is unchanged after both.

No server↔daemon wire contract changed, so HOST_DAEMON_PROTOCOL_VERSION is unchanged. No new CLI flag, command, or configuration knob, so no guide or skill surface needed an update.

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Fixes #2166

AGENT GENERATED: by Claude Opus 5