feat(desktop): add an operational topology view for Agent Graph #2596

Problem

Maka Desktop already has an AgentGraphPanel, but it renders Graph state as a flat list of operators. Users can see aggregate progress, one status and wait reason per visible operator, selected result IDs, and links to child Sessions; they cannot see the topology that makes the feature a graph:

• which operators depend on which upstream operators;
• where work fans out or joins;
• why a downstream operator is waiting in the context of the whole flow;
• which path is currently running, blocked, failed, or complete;
• how dynamically added work changed the execution shape.

This makes a multi-stage Graph difficult to understand at a glance. The Runtime read model already exposes stable operators, edges, work, readiness, status, and omission metadata, so the missing piece is primarily a Desktop presentation and interaction surface.

The current architecture intentionally describes the panel as an operational inspection/stop view rather than a visual graph editor. This issue preserves that boundary: the goal is to make live delegated work understandable, not to add a decorative diagram or a workflow-authoring system.

Desired outcome

Add a read-only operational topology view for Agent Graph in the delegated-work / session workbar surface planned by #1457.

The view should:

• render operators as nodes and declared dependencies as directed edges;
• make fan-out, chains, and fan-in/join structures legible;
• show node state (not_started, waiting, runnable, running, blocked, and terminal states) with text/icon semantics in addition to color;
• expose the most useful work instruction preview and wait reason without requiring users to open every child Session;
• let users select an operator to inspect its bounded details and open the linked child Session;
• update from the existing Graph invalidation/query contract while keeping layout reasonably stable as operators are added or statuses change;
• preserve a compact list/table alternative for accessibility, narrow windows, and cases where a graph layout is less useful;
• represent loading, empty, error, stopped, completed, and omitted/truncated states honestly;
• remain usable with larger bounded snapshots through pan/zoom, fit-to-view, incremental layout, or equivalent interaction;
• use the existing Desktop design system and support current themes.

Suggested acceptance scenarios:

1. A → B → C reads clearly as a sequential dependency chain.
2. A fans out to B and C, then B + C feed D; the join and D's waiting reason are visible.
3. One branch fails while another completes; the active and terminal paths remain distinguishable without relying only on color.
4. A supervisor adds an operator during execution; the view updates without resetting the user's selection or needlessly jumping the viewport.
5. A bounded snapshot reports omitted operators or edges; the UI states that the displayed topology is partial rather than implying completeness.
6. Selecting a node can open its child Session and inspect the data already exposed by graphs.inspectOperator.
7. Restart/reconnect reconstructs the same view from durable Graph state; renderer-local layout state is never treated as execution authority.

Non-goals

• Creating, deleting, rewiring, or dragging Graph operators/edges to change execution.
• A general workflow editor or arbitrary cyclic graph authoring.
• Adding a second Graph/event store or deriving execution state from renderer state.
• Replacing the chronological trace / replay work from Graph trace reconstruction: expose a replayable control/data-plane timeline #1529 or the broader Session Inspector in [RFC] Session Inspector: a per-session runtime event trace, replay, and cost-attribution surface #1625.
• Shipping a decorative graph before delegated-work status and waiting conditions remain understandable.

Alternatives or workarounds

• Keep using the current flat operator list and open child Sessions one by one. This exposes individual status but hides dependency shape.
• Render only a chronological event timeline. Useful for diagnosis, but it answers “what happened when,” not “what depends on what now.”
• Generate a static Mermaid/DOT diagram. This does not provide live status, selection, child-session navigation, bounded omission handling, or reconnect behavior.
• Add the visualization as a standalone panel. feat(desktop): surface linked child sessions in the session workbar #1457 and roadmap(product): evolve Maka into a durable Agent workspace #2469 point toward one delegated-work surface, so folding the topology view into that surface avoids competing Graph UIs.

Related

• design(runtime): model subagent orchestration as a supervised stream graph #1341 — original supervised stream-graph design; its delivery plan explicitly deferred a full graph visualization / scalable explorer.
• feat(desktop): surface linked child sessions in the session workbar #1457 — moves linked child Sessions and the existing Graph panel into the session workbar.
• Graph trace reconstruction: expose a replayable control/data-plane timeline #1529 — delivered the replayable control/data-plane timeline; Desktop timeline presentation remains a separate observability concern.
• [RFC] Session Inspector: a per-session runtime event trace, replay, and cost-attribution surface #1625 — broader per-session causal timeline / Inspector.
• roadmap(product): evolve Maka into a durable Agent workspace #2469 — product roadmap; this proposal is operational information architecture, not a decorative visualization.