[codex] Add issue monitor liveness controls (#4988)

## Thinking Path

> - Paperclip is a control plane for autonomous AI companies where work
must stay observable, governable, and recoverable.
> - The task/heartbeat subsystem owns agent execution continuity, issue
state transitions, and visible recovery behavior.
> - Waiting on an external service is not the same as being blocked when
the assignee still owns a future check.
> - The gap was that agents had no first-class one-shot monitor state
for external-service waits, so recovery could look stalled or require ad
hoc comments.
> - This pull request adds bounded issue monitors that can wake the
owner, clear exhausted waits, and produce explicit recovery behavior.
> - It also surfaces monitor status in the board UI and documents when
to use monitors versus `blocked`.
> - The benefit is clearer liveness semantics for asynchronous waits
without weakening single-assignee task ownership.

## What Changed

- Added issue monitor fields, shared types, validators, constants, and
an idempotent `0075` migration for scheduled monitor state.
- Added server-side monitor scheduling, dispatch, recovery bounds,
activity logging, and external-ref redaction.
- Added board/agent route coverage for monitor permissions and child
monitor scheduling.
- Added issue detail/property UI for monitor state, a monitor activity
card, and Storybook stories for review surfaces.
- Documented monitor semantics and recovery policy behavior in
`doc/execution-semantics.md`.
- Addressed Greptile review feedback by preserving monitor state in
skipped-stage builders and making board monitor saves send `scheduledBy:
"board"`.

## Verification

- `pnpm install --frozen-lockfile`
- `pnpm run preflight:workspace-links && pnpm exec vitest run
server/src/__tests__/issue-execution-policy-routes.test.ts
server/src/__tests__/issue-execution-policy.test.ts
server/src/__tests__/issue-monitor-scheduler.test.ts
server/src/__tests__/recovery-classifiers.test.ts
ui/src/components/IssueMonitorActivityCard.test.tsx
ui/src/components/IssueProperties.test.tsx
ui/src/lib/activity-format.test.ts`
- First run passed 5 files and failed to collect 2 server suites because
the worktree was missing the optional `acpx/runtime` dependency.
- After `pnpm install --frozen-lockfile`, reran the 2 failed suites
successfully.
- `pnpm exec vitest run
server/src/__tests__/issue-monitor-scheduler.test.ts
server/src/__tests__/recovery-classifiers.test.ts`
- `pnpm --filter @paperclipai/shared typecheck && pnpm --filter
@paperclipai/db typecheck && pnpm --filter @paperclipai/server typecheck
&& pnpm --filter @paperclipai/ui typecheck`
- `pnpm exec vitest run
server/src/__tests__/issue-execution-policy.test.ts
ui/src/components/IssueProperties.test.tsx`
- `pnpm --filter @paperclipai/server typecheck && pnpm --filter
@paperclipai/ui typecheck`
- `pnpm exec vitest run
ui/src/components/IssueMonitorActivityCard.test.tsx
ui/src/components/IssueProperties.test.tsx`
- `pnpm --filter @paperclipai/ui typecheck`
- Storybook screenshot captured from
`http://127.0.0.1:6006/iframe.html?viewMode=story&id=product-issue-monitor-surfaces--monitor-surfaces`
with Playwright.

## Screenshots

![Issue monitor Storybook
surfaces](https://raw.githubusercontent.com/paperclipai/paperclip/PAP-2945-when-a-task-is-waiting-for-an-_external-service_-what-state-should-it-be-in-and-what-recovery-method-could-it-h/docs/pr-screenshots/pap-2945/monitor-surfaces.png)

## Risks

- Medium: this changes heartbeat recovery behavior for scheduled
external-service waits, so regressions could affect wake timing or
recovery issue creation.
- Migration risk is reduced by using `IF NOT EXISTS` for the new issue
monitor columns and index.
- External monitor references are treated as secret-adjacent and are
intentionally omitted from visible activity/wake payloads.

> For core feature work, check [`ROADMAP.md`](ROADMAP.md) first and
discuss it in `#dev` before opening the PR. Feature PRs that overlap
with planned core work may need to be redirected — check the roadmap
first. See `CONTRIBUTING.md`.

## Model Used

- OpenAI Codex, GPT-5 coding agent with repository tool use and terminal
execution.

## Checklist

- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used (with version and capability
details)
- [x] I have checked ROADMAP.md and confirmed this PR does not duplicate
planned core work
- [x] I have run tests locally and they pass
- [x] I have added or updated tests where applicable
- [x] If this change affects the UI, I have included before/after
screenshots or Storybook review surfaces
- [x] I have updated relevant documentation to reflect my changes
- [x] I have considered and documented any risks above
- [x] I will address all Greptile and reviewer comments before
requesting merge

---------

Co-authored-by: Paperclip <noreply@paperclip.ing>

packages/shared/src/validators/issue.ts

@@ -1,9 +1,14 @@
 import { z } from "zod";
 import {
   ISSUE_EXECUTION_DECISION_OUTCOMES,
+  ISSUE_EXECUTION_MONITOR_CLEAR_REASONS,
+  ISSUE_EXECUTION_MONITOR_KINDS,
+  ISSUE_EXECUTION_MONITOR_RECOVERY_POLICIES,
+  ISSUE_EXECUTION_MONITOR_STATE_STATUSES,
   ISSUE_EXECUTION_POLICY_MODES,
   ISSUE_EXECUTION_STAGE_TYPES,
   ISSUE_EXECUTION_STATE_STATUSES,
+  ISSUE_MONITOR_SCHEDULED_BY,
   ISSUE_PRIORITIES,
   clampIssueRequestDepth,
   ISSUE_STATUSES,
@@ -103,10 +108,40 @@ export const issueExecutionStageSchema = z.object({
   participants: z.array(issueExecutionStageParticipantSchema).default([]),
 });
 
+export const issueExecutionMonitorPolicySchema = z.object({
+  nextCheckAt: z.string().datetime(),
+  notes: z.string().max(500).optional().nullable().default(null),
+  scheduledBy: z.enum(ISSUE_MONITOR_SCHEDULED_BY).optional().default("assignee"),
+  kind: z.enum(ISSUE_EXECUTION_MONITOR_KINDS).optional().nullable().default(null),
+  serviceName: z.string().trim().min(1).max(120).optional().nullable().default(null),
+  externalRef: z.string().trim().min(1).max(500).optional().nullable().default(null),
+  timeoutAt: z.string().datetime().optional().nullable().default(null),
+  maxAttempts: z.number().int().positive().max(100).optional().nullable().default(null),
+  recoveryPolicy: z.enum(ISSUE_EXECUTION_MONITOR_RECOVERY_POLICIES).optional().nullable().default(null),
+});
+
 export const issueExecutionPolicySchema = z.object({
   mode: z.enum(ISSUE_EXECUTION_POLICY_MODES).optional().default("normal"),
   commentRequired: z.boolean().optional().default(true),
   stages: z.array(issueExecutionStageSchema).default([]),
+  monitor: issueExecutionMonitorPolicySchema.optional().nullable(),
+});
+
+export const issueExecutionMonitorStateSchema = z.object({
+  status: z.enum(ISSUE_EXECUTION_MONITOR_STATE_STATUSES),
+  nextCheckAt: z.string().datetime().nullable(),
+  lastTriggeredAt: z.string().datetime().nullable(),
+  attemptCount: z.number().int().nonnegative().default(0),
+  notes: z.string().max(500).nullable(),
+  scheduledBy: z.enum(ISSUE_MONITOR_SCHEDULED_BY).nullable(),
+  kind: z.enum(ISSUE_EXECUTION_MONITOR_KINDS).nullable().optional().default(null),
+  serviceName: z.string().trim().min(1).max(120).nullable().optional().default(null),
+  externalRef: z.string().trim().min(1).max(500).nullable().optional().default(null),
+  timeoutAt: z.string().datetime().nullable().optional().default(null),
+  maxAttempts: z.number().int().positive().max(100).nullable().optional().default(null),
+  recoveryPolicy: z.enum(ISSUE_EXECUTION_MONITOR_RECOVERY_POLICIES).nullable().optional().default(null),
+  clearedAt: z.string().datetime().nullable(),
+  clearReason: z.enum(ISSUE_EXECUTION_MONITOR_CLEAR_REASONS).nullable(),
 });
 
 export const issueReviewRequestSchema = z.object({
@@ -124,6 +159,7 @@ export const issueExecutionStateSchema = z.object({
   completedStageIds: z.array(z.string().uuid()).default([]),
   lastDecisionId: z.string().uuid().nullable(),
   lastDecisionOutcome: z.enum(ISSUE_EXECUTION_DECISION_OUTCOMES).nullable(),
+  monitor: issueExecutionMonitorStateSchema.optional().nullable(),
 });
 
 const issueRequestDepthInputSchema = z