refactor(integrations): split issue-tracker clients under the max-lines budget (#14704)

The GitLab, GitHub, Jira and Linear integration modules, their two IPC
registrars, and the shared GitHub project types each carried a file-level
`eslint-disable max-lines` and ran 351-614 counted lines against a 300-line
budget. AGENTS.md calls for splitting rather than suppressing, and
config/max-lines-baseline.txt is a shrink-only ratchet, so this removes all
eight suppressions and prunes their entries (341 -> 333).

Pure move, no behavior change. Each client is cut along the seam it already
had: per-operation modules for the issue APIs (create / update / comment /
field options), and for Jira the request queue, site credential store,
authenticated request, and site identity. The two IPC registrars keep their own
handlers and delegate the rest to per-domain sub-registrars, so they remain
real entry points rather than re-export shims.

The IPC surface is proved intact rather than assumed: comparing (method,
channel) multisets between HEAD and the split gives 52 registrations across 52
distinct channels on both sides.

Provider-neutrality is preserved -- GitLab and GitHub keep separate, parallel
module layouts rather than being merged behind a shared abstraction.

Verified: oxlint clean, ratchet passes, typecheck clean, full unit suite green
(the one remaining failure is a pre-existing load flake in an untouched file,
green when re-run serially), no new runtime import cycles among 744 modules,
and no lint suppression added anywhere.

src/main/github/issue-update.ts

@@ -0,0 +1,130 @@
+import type { GitHubIssueUpdate } from '../../shared/issue-mutation-types'
+import type { LocalGitExecOptions } from './gh-utils'
+import { getIssueGitHubApiRepository, resolveGitHubRepoExecution } from './github-api-repository'
+import { acquire, classifyGhError, ghExecFileAsync, release } from './gh-utils'
+
+/**
+ * Update an existing GitHub issue. Fans out to separate gh commands for
+ * state changes vs field edits since `gh issue edit` does not support state.
+ *
+ * Why this path doesn't take a preference (mirrors `getIssue`): mutations
+ * target an issue number already bound to a worktree / linked elsewhere in
+ * the UI. Routing an update through the live per-repo preference would let
+ * a user open upstream#N, toggle the selector to origin, save, and silently
+ * write to origin#N — a different issue (or 404). That is the exact
+ * silent-source-switch class of wrongness #1186 / the parent design doc
+ * guard against. List and create paths honor preference; mutations stay on
+ * the heuristic `getIssueOwnerRepo`.
+ */
+export async function updateIssue(
+  repoPath: string,
+  issueNumber: number,
+  updates: GitHubIssueUpdate,
+  connectionId?: string | null,
+  localGitOptions: LocalGitExecOptions = {}
+): Promise<{ ok: true } | { ok: false; error: string }> {
+  const { ownerRepo, ghOptions } = await resolveGitHubRepoExecution(
+    repoPath,
+    () => getIssueGitHubApiRepository(repoPath, connectionId, localGitOptions),
+    connectionId,
+    localGitOptions
+  )
+  if (!ownerRepo) {
+    return { ok: false, error: 'Could not resolve GitHub owner/repo for this repository' }
+  }
+
+  const repo = `${ownerRepo.owner}/${ownerRepo.repo}`
+  const errors: string[] = []
+
+  // State change requires a separate command
+  if (updates.state) {
+    await acquire()
+    try {
+      if (updates.state === 'closed') {
+        const closeArgs = ['issue', 'close', String(issueNumber), '--repo', repo]
+        if (updates.stateReason === 'completed') {
+          closeArgs.push('--reason', 'completed')
+        } else if (updates.stateReason === 'not_planned') {
+          closeArgs.push('--reason', 'not planned')
+        } else if (updates.stateReason === 'duplicate' && updates.duplicateOf) {
+          closeArgs.push('--duplicate-of', String(updates.duplicateOf))
+        }
+        await ghExecFileAsync(closeArgs, ghOptions)
+      } else {
+        await ghExecFileAsync(['issue', 'reopen', String(issueNumber), '--repo', repo], ghOptions)
+      }
+    } catch (err) {
+      const stderr = err instanceof Error ? err.message : String(err)
+      // Treat "already closed/open" as a no-op
+      if (!stderr.toLowerCase().includes('already')) {
+        errors.push(classifyGhError(stderr).message)
+      }
+    } finally {
+      release()
+    }
+  }
+
+  if (updates.body !== undefined) {
+    await acquire()
+    try {
+      await ghExecFileAsync(
+        [
+          'api',
+          '-X',
+          'PATCH',
+          `repos/${ownerRepo.owner}/${ownerRepo.repo}/issues/${issueNumber}`,
+          '--raw-field',
+          `body=${updates.body}`
+        ],
+        ghOptions
+      )
+    } catch (err) {
+      const stderr = err instanceof Error ? err.message : String(err)
+      errors.push(classifyGhError(stderr).message)
+    } finally {
+      release()
+    }
+  }
+
+  // Field edits (labels, assignees, title) via gh issue edit
+  const editArgs: string[] = ['issue', 'edit', String(issueNumber), '--repo', repo]
+  let hasEditArgs = false
+
+  if (updates.title) {
+    editArgs.push('--title', updates.title)
+    hasEditArgs = true
+  }
+  for (const label of updates.addLabels ?? []) {
+    editArgs.push('--add-label', label)
+    hasEditArgs = true
+  }
+  for (const label of updates.removeLabels ?? []) {
+    editArgs.push('--remove-label', label)
+    hasEditArgs = true
+  }
+  for (const assignee of updates.addAssignees ?? []) {
+    editArgs.push('--add-assignee', assignee)
+    hasEditArgs = true
+  }
+  for (const assignee of updates.removeAssignees ?? []) {
+    editArgs.push('--remove-assignee', assignee)
+    hasEditArgs = true
+  }
+
+  if (hasEditArgs) {
+    await acquire()
+    try {
+      await ghExecFileAsync(editArgs, ghOptions)
+    } catch (err) {
+      const stderr = err instanceof Error ? err.message : String(err)
+      errors.push(classifyGhError(stderr).message)
+    } finally {
+      release()
+    }
+  }
+
+  if (errors.length > 0) {
+    return { ok: false, error: errors.join('; ') }
+  }
+  return { ok: true }
+}