ADE-56: Guard agentChatGetEventHistory IPC handler against null agentChatService in runtime-backed mode

[arul28]

Fixes ADE-56

Summary

Describe the change.

What Changed

Key files and behaviors.

Validation

How you tested.

Risks

Anything to watch.

Linked Linear issues

• ADE-56: Guard agentChatGetEventHistory IPC handler against null agentChatService in runtime-backed mode - closes on merge

  Open in ADE  ·  ade-56-guard-agentchatgeteventhistory-ipc-handler-against-null-agentchatservice-in-runtime-backed-mode branch  ·  PR #431

Summary by CodeRabbit

• Bug Fixes

  • More robust chat event history handling: when the chat service or its history method is unavailable, the app now returns a safe empty history snapshot instead of failing; requests also normalize session IDs and only forward valid maxEvents.

• Tests

  • Added unit tests covering missing service, missing history support, and successful history retrieval scenarios.

Greptile Summary

Guards the agentChatGetEventHistory IPC handler against a null agentChatService, which occurs in runtime-backed mode where the service isn't instantiated. Instead of calling ensureAgentChatContext() (which throws), the handler now calls getCtx() directly and returns an empty history snapshot when the service is absent or lacks the method.

• registerIpc.ts: Replaces ensureAgentChatContext() with getCtx() + a two-condition guard (!service || typeof service.getChatEventHistory !== "function"), consistent with the existing pattern in agentChatReadTranscript.
• runtimeBridge.test.ts: Adds tests for null service, service missing the method (duck-type branch), and the successful forwarding path — full branch coverage for the new guard.

Confidence Score: 5/5

Safe to merge — the change adds a well-tested null guard that prevents a crash in runtime-backed mode and is consistent with the existing pattern used by the adjacent agentChatReadTranscript handler.

The guard logic is straightforward, the change is isolated to a single handler, all three new code paths have direct unit-test coverage, and the implementation mirrors an existing pattern in the same file.

No files require special attention.

Important Files Changed

Filename	Overview
apps/desktop/src/main/services/ipc/registerIpc.ts	Switches agentChatGetEventHistory from ensureAgentChatContext() (throws on null) to getCtx() + explicit null/duck-type guard, returning an empty snapshot instead of throwing when agentChatService is unavailable.
apps/desktop/src/main/services/ipc/runtimeBridge.test.ts	Adds three unit tests covering: null service, service without getChatEventHistory (duck-type branch), and happy path — fully covering all new guard branches.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[IPC: agentChatGetEventHistory] --> B[getCtx]
    B --> C{sessionId valid?}
    C -- No --> D[return empty snapshot\nsessionId: '']
    C -- Yes --> E{service present AND\ngetChatEventHistory is function?}
    E -- No --> F[return empty snapshot\nsessionId: trimmed]
    E -- Yes --> G{maxEvents valid\nfinite positive number?}
    G -- No --> H[maxEvents = undefined]
    G -- Yes --> I[maxEvents = rawMaxEvents]
    H --> J[service.getChatEventHistory\nsessionId, undefined]
    I --> K[service.getChatEventHistory\nsessionId, maxEvents]

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Comments Outside Diff (1)

1. apps/desktop/src/main/services/ipc/registerIpc.ts, line 671 (link)

   AppContext type doesn't reflect nullable agentChatService

   main.ts explicitly sets agentChatService: null for the runtime-backed context (line 4304), so the field is null at runtime in that mode. However, AppContext still declares it as ReturnType<typeof createAgentChatService> — non-optional, non-nullable. As a result, TypeScript won't flag any future call sites that access the service without a null guard, meaning the pattern this PR protects against can silently recur. Updating the type to ReturnType<typeof createAgentChatService> | null (matching the treatment of other nullable services like devToolsService) would make the type system enforce the guard everywhere.

   Prompt To Fix With AI

   This is a comment left during a code review.
   Path: apps/desktop/src/main/services/ipc/registerIpc.ts
   Line: 671
   
   Comment:
   **`AppContext` type doesn't reflect nullable `agentChatService`**
   
   `main.ts` explicitly sets `agentChatService: null` for the runtime-backed context (line 4304), so the field is null at runtime in that mode. However, `AppContext` still declares it as `ReturnType<typeof createAgentChatService>` — non-optional, non-nullable. As a result, TypeScript won't flag any future call sites that access the service without a null guard, meaning the pattern this PR protects against can silently recur. Updating the type to `ReturnType<typeof createAgentChatService> | null` (matching the treatment of other nullable services like `devToolsService`) would make the type system enforce the guard everywhere.
   
   How can I resolve this? If you propose a fix, please make it concise.

   Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!

   

_{Reviews (4): Last reviewed commit: "fix: guard chat event history IPC servic..." | Re-trigger Greptile}

[linear-code]

ADE-56

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
ade	Ignored	Preview	May 30, 2026 7:56am

[coderabbitai]

📝 Walkthrough

Walkthrough

The IPC handler for agentChatEventHistory now verifies agentChatService and its getChatEventHistory method before calling them, returning an empty event snapshot when missing. Tests added cover missing-service, missing-method, and successful-forwarding scenarios.

Changes

Defensive IPC Handler for Agent Chat Event History

Layer / File(s)	Summary
Handler: service presence and method guard apps/desktop/src/main/services/ipc/registerIpc.ts	The IPC handler assigns ctx.agentChatService to a local service variable and early-returns an empty event history (events: [], truncated: false, sessionFound: false) when the service or its getChatEventHistory method is missing. When available, it invokes service.getChatEventHistory with sanitized sessionId and maxEvents only if valid.
Tests: null/missing method and forwarding apps/desktop/src/main/services/ipc/runtimeBridge.test.ts	Three Vitest cases: (1) agentChatService is null -> empty normalized history, (2) service present but no getChatEventHistory -> empty normalized history, (3) service with getChatEventHistory -> forwards trimmed sessionId and maxEvents, returns snapshot and asserts call args.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related issues

• Guard agentChatGetEventHistory IPC handler against null agentChatService in runtime-backed mode #411 — The change addresses the null/function guard and default empty snapshot behavior for agentChatGetEventHistory described in the issue.

Suggested labels

desktop

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The pull request title clearly and specifically describes the main change: guarding the agentChatGetEventHistory IPC handler against null agentChatService in runtime-backed mode, which is the core focus of the changeset.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch ade-56-guard-agentchatgeteventhistory-ipc-handler-against-null-agentchatservice-in-runtime-backed-mode

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[arul28]

@copilot review but do not make fixes

[capy-ai]

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[arul28]

Rebased on latest main and addressed Greptile review by adding coverage for a truthy agentChatService without getChatEventHistory. Re-ran the focused IPC test and desktop typecheck; both pass.

[arul28]

Rebased again on latest main after ADE-51 and #442 landed, resolving the test conflict by preserving both agentChatList and agentChatGetEventHistory IPC regression coverage. Re-ran focused IPC test and desktop typecheck successfully before force-pushing 5cba84c.