Mark a loop watching the Mailroom with an envelope glyph

[scgopi]

Implements Option A from the Mailroom-watch design canvas (https://claude.ai/code/artifact/b66281a3-4d39-435d-8a92-ecc0eb4a0b6f): a quiet outline envelope glyph marking a loop that is watching the Mailroom, in two places only.

What

• Sidebar row (AppSidebarView.nodeRow): envelope SF Symbol between the title's spacer and the age text, 10pt, white at 45%.
• Canvas card (LoopCardView.metaRow): same glyph after the existing 9pt network remote glyph, 9pt, white at 40%.
• Both shown only when node.mailroomWatch != nil and the node is not resolved, and both carry a .help tooltip: Watching the Mailroom, or Watching the Mailroom · topic <t> when the watch has a topic.
• New MailroomWatchPresentation enum answers "show glyph?" and "tooltip text" from a LoopNode, so the rule lives in one place and is testable without pixels.

No colour, no count, no unread dot — Option B is explicitly out of scope.

Tests

MailroomWatchPresentationTests: no watch, watch on every post, watch with a topic, and a watch on a resolved node (hidden) parameterised over all four resolved states.

Gate

In flight from the worktree with private DerivedData; literal exit codes to follow in a comment.

🤖 Generated with Claude Code

https://claude.ai/code/session_01M8s9Ranjzra1VAKrP27gN7

[scgopi]

Gate on 290b0080 (= remote head = PR head), worktree worktrees/mailroom-watch-glyph, private DerivedData (.derived):

• xcodebuild test exit 0 — 1699 tests / 181 suites / 0 failures; MailroomWatchPresentationTests ran and passed (3 tests + 1 parameterised over the 4 resolved states)
• graphcode-cli build exit 0
• graphcoded build exit 0
• swiftlint 0 errors (standing warnings only); swift-format lint --strict exit 0
• scripts/cli-smoke.sh exit 0 against a fresh SwiftPM build in .spm (the worktree's shared .build symlink would have run a stale binary), throwaway daemon, five verbs ok
• Linux: pass — https://github.com/scgopi/GraphCode/actions/runs/34200682646/job/101978521506

[scgopi]

Re-gate on 5710e946 (= remote head = PR head) after the review nits — comments trimmed to the retained-watch rationale; showsGlyph kept because the brief asked the helper to answer both "show glyph?" and "tooltip text". Private DerivedData:

• xcodebuild test exit 0 — 1699 tests / 181 suites / 0 failures; MailroomWatchPresentationTests passed
• graphcode-cli build exit 0; graphcoded build exit 0
• swiftlint 0 errors; swift-format lint --strict exit 0
• cli-smoke.sh exit 0 (fresh .spm build, five verbs ok)
• Linux: pass — https://github.com/scgopi/GraphCode/actions/runs/34203522326/job/101987588331

For the record: the first re-run on this head exited 65 with one failure, CodexReadinessGateTests.aSessionLabelledForAnotherAgentIsNotAdopted — its start() helper launches a real zmx session and polls zmx ls 40×100ms, and under machine load the session had not appeared. Unrelated to this comment-only diff; the clean re-run above is the gate.