hermes - 💡(How to fix) Fix Feature: Add scheduled_at for deferred Kanban task dispatch

Summary

Add a scheduled_at column to the Kanban tasks table so tasks can be deferred until a specific time. The dispatcher skips tasks whose scheduled time has not arrived yet.

Motivation

Users want to create tasks that should not start until a future time — e.g. "run this report tomorrow at 9am", "deploy Friday evening", or "revisit this bug after the upstream fix lands next week".

Currently tasks are either ready (dispatched immediately) or blocked by parent dependencies. There is no time-based gating mechanism.

Proposed Design

Schema: Add scheduled_at INTEGER column to tasks table (nullable, NULL = no scheduling constraint).

Dispatcher gate: In dispatch_once(), change the ready-tasks query:

-- Before
SELECT id, assignee FROM tasks
WHERE status = 'ready' AND claim_lock IS NULL
ORDER BY priority DESC, created_at ASC

-- After
SELECT id, assignee FROM tasks
WHERE status = 'ready' AND claim_lock IS NULL
AND (scheduled_at IS NULL OR scheduled_at <= ?)
ORDER BY priority DESC, created_at ASC

The ? parameter is int(time.time()). Same guard in claim_task() to prevent manual claims on not-yet-eligible tasks.

Tool parameter: Add scheduled_at (integer, unix epoch) to kanban_create schema:

"scheduled_at": {
    "type": "integer",
    "description": "Unix timestamp. Task will not be dispatched until this time."
}

Index: Partial index on scheduled_at for rows where it is not NULL.

Files Changed

• hermes_cli/kanban_db.py — schema, dataclass, create_task, dispatch gate, claim gate
• tools/kanban_tools.py — kanban_create schema + handler passthrough

Backward Compatibility

• Purely additive: new nullable column, new optional parameter
• NULL scheduled_at = no scheduling = existing behavior completely unchanged
• No new status in the lifecycle — invisible to consumers that do not use it

Alternatives Considered

New scheduled status — Rejected because it adds a status to the lifecycle requiring changes to every consumer (UI, health checks, recompute logic). The column approach is invisible to non-consumers.

Full Spec

Detailed implementation spec with exact line numbers: SCHEDULED_TASKS_SPEC.md (will be in PR)