Add workflow interaction cancellation and issue cost summaries (#4862)

## Thinking Path

> - Paperclip coordinates work through issue-thread interactions, run
history, and cost telemetry.
> - Operators need workflow prompts to be cancellable and costs to be
visible at the issue level.
> - The earlier rollup mixed this workflow/cost work with database
backups, reliability recovery, thread scaling, and settings polish.
> - This pull request isolates the interaction and cost surfaces into a
reviewable slice.
> - The backend now supports cancelling pending question interactions
and summarizing issue-tree costs.
> - The UI component layer can render cancelled questions and interleave
activity with run ledger rows.

## What Changed

- Added `cancelled` as an issue-thread interaction status and result
shape for question interactions.
- Added the board-only `POST
/issues/:id/interactions/:interactionId/cancel` route and service
implementation.
- Added issue-tree cost summary support in the cost service and
`/issues/:id/cost-summary` API route.
- Extended shared cost exports and UI API/query keys for issue cost
summaries.
- Updated `IssueThreadInteractionCard` and `IssueRunLedger` components
for cancelled questions, issue cost surfaces, and activity/run
interleaving.
- Added focused server and component regression coverage.

## Verification

- `pnpm install --frozen-lockfile`
- `pnpm exec vitest run server/src/__tests__/costs-service.test.ts
server/src/__tests__/issue-thread-interaction-routes.test.ts
server/src/__tests__/issue-thread-interactions-service.test.ts
ui/src/components/IssueRunLedger.test.tsx`
- Result: 4 test files passed, 45 tests passed.
- UI screenshots not included because this PR updates reusable
components and API surfaces without wiring a new page-level layout.

## Risks

- Adds a new interaction terminal status; clients that switch
exhaustively on interaction status may need to handle `cancelled`.
- Issue-tree cost summaries use recursive issue traversal and should be
watched on unusually large issue trees.
- Page-level issue detail wiring is intentionally left to the board
QoL/issue-detail branch to keep this PR narrow.

> 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-5.5, code execution and GitHub CLI tool use, medium
reasoning effort.

## 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
- [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/constants.ts

@@ -160,6 +160,7 @@ export const ISSUE_THREAD_INTERACTION_STATUSES = [
   "accepted",
   "rejected",
   "answered",
+  "cancelled",
   "expired",
   "failed",
 ] as const;

packages/shared/src/index.ts

@@ -396,6 +396,7 @@ export type {
   BudgetIncidentResolutionInput,
   CostEvent,
   CostSummary,
+  IssueCostSummary,
   CostByAgent,
   CostByProviderModel,
   CostByBiller,
@@ -670,6 +671,7 @@ export {
   createIssueThreadInteractionSchema,
   acceptIssueThreadInteractionSchema,
   rejectIssueThreadInteractionSchema,
+  cancelIssueThreadInteractionSchema,
   respondIssueThreadInteractionSchema,
   linkIssueApprovalSchema,
   createIssueAttachmentMetadataSchema,
@@ -704,6 +706,7 @@ export {
   type CreateIssueThreadInteraction,
   type AcceptIssueThreadInteraction,
   type RejectIssueThreadInteraction,
+  type CancelIssueThreadInteraction,
   type RespondIssueThreadInteraction,
   type LinkIssueApproval,
   type CreateIssueAttachmentMetadata,

packages/shared/src/types/cost.ts

@@ -28,6 +28,16 @@ export interface CostSummary {
   utilizationPercent: number;
 }
 
+export interface IssueCostSummary {
+  issueId: string;
+  issueCount: number;
+  includeDescendants: boolean;
+  costCents: number;
+  inputTokens: number;
+  cachedInputTokens: number;
+  outputTokens: number;
+}
+
 export interface CostByAgent {
   agentId: string;
   agentName: string | null;

packages/shared/src/types/index.ts

@@ -227,7 +227,7 @@ export type {
   RoutineExecutionIssueOrigin,
   RoutineListItem,
 } from "./routine.js";
-export type { CostEvent, CostSummary, CostByAgent, CostByProviderModel, CostByBiller, CostByAgentModel, CostWindowSpendRow, CostByProject } from "./cost.js";
+export type { CostEvent, CostSummary, IssueCostSummary, CostByAgent, CostByProviderModel, CostByBiller, CostByAgentModel, CostWindowSpendRow, CostByProject } from "./cost.js";
 export type { FinanceEvent, FinanceSummary, FinanceByBiller, FinanceByKind } from "./finance.js";
 export type {
   AgentWakeupResponse,

packages/shared/src/types/issue.ts

@@ -386,6 +386,8 @@ export interface AskUserQuestionsAnswer {
 export interface AskUserQuestionsResult {
   version: 1;
   answers: AskUserQuestionsAnswer[];
+  cancelled?: true;
+  cancellationReason?: string | null;
   summaryMarkdown?: string | null;
 }
 

packages/shared/src/validators/index.ts

@@ -177,6 +177,7 @@ export {
   createIssueThreadInteractionSchema,
   acceptIssueThreadInteractionSchema,
   rejectIssueThreadInteractionSchema,
+  cancelIssueThreadInteractionSchema,
   respondIssueThreadInteractionSchema,
   linkIssueApprovalSchema,
   createIssueAttachmentMetadataSchema,
@@ -194,6 +195,7 @@ export {
   type CreateIssueThreadInteraction,
   type AcceptIssueThreadInteraction,
   type RejectIssueThreadInteraction,
+  type CancelIssueThreadInteraction,
   type RespondIssueThreadInteraction,
   type LinkIssueApproval,
   type CreateIssueAttachmentMetadata,

packages/shared/src/validators/issue.ts

@@ -330,6 +330,8 @@ export const askUserQuestionsAnswerSchema = z.object({
 export const askUserQuestionsResultSchema = z.object({
   version: z.literal(1),
   answers: z.array(askUserQuestionsAnswerSchema).max(20),
+  cancelled: z.literal(true).optional(),
+  cancellationReason: z.string().trim().max(4000).nullable().optional(),
   summaryMarkdown: z.string().max(20000).nullable().optional(),
 });
 
@@ -446,6 +448,11 @@ export const rejectIssueThreadInteractionSchema = z.object({
 });
 export type RejectIssueThreadInteraction = z.infer<typeof rejectIssueThreadInteractionSchema>;
 
+export const cancelIssueThreadInteractionSchema = z.object({
+  reason: z.string().trim().max(4000).optional(),
+});
+export type CancelIssueThreadInteraction = z.infer<typeof cancelIssueThreadInteractionSchema>;
+
 export const respondIssueThreadInteractionSchema = z.object({
   answers: z.array(askUserQuestionsAnswerSchema).max(20),
   summaryMarkdown: multilineTextSchema.pipe(z.string().max(20000)).nullable().optional(),