Selected Work

Contenteditable tokens with favicon, title, and URL. Caret-aware deletion, drag-select, and keyboard support. Feels like a real tag input, not a regex on a textarea.

Roughly two dozen browser tasks scored on five axes: correctness, recovery, hallucination, latency, and tool-use shape. Turns vague "it broke" reports into a specific failing case and gates every patch before it ships.

Subagent now requires a fresh page snapshot before any interaction, addresses elements by visible text rather than row position, and verifies the post-navigation URL before claiming success. Per-spec step budget raised from 25 to 50 so multi-step form flows finish without hitting the cap.

Replace versus append used to be a flag on a single verb, leaving the agent cycling through fallbacks. Splitting them deleted the ambiguity. Swapped the field-focus path from three simulated mouse events to a direct focus call: fill operations went from about 5,000ms to 40ms.

Single CDP session per browser, resolves target tab (current vs. new), runs tool calls, and releases on 60s idle. Show/hide overlay and screenshot/snapshot caches hang off the session lifecycle.

Current tabs feed into a per-message context field and clear after send. Stops yesterday's selection from quietly riding along on tomorrow's question.

Extracted from the conversation store. Accumulates partial JSON for tool inputs, embeds tool results into the right block, and tracks subagent state alongside the parent turn.

Replaced a CSS glowing frame that felt too quiet next to the rest of the UI. Custom vertex and fragment shaders, 60fps RAF loop, debounced fade-out after the last tool call.

Converts JSON schemas from the extension into StructuredTools at session start. Depth, property-count, and enum-cardinality guards keep a hostile schema from blowing up the agent.

Click, type, navigate, wait_for_selector, snapshot, and ~25 more, all schema-validated client-side before dispatch. Actionability checks live next to tool execution.

ChatEventSerializer owns block-index correlation, orphan event filtering, and text coalescing. Stream service is now a thin transport that doesn't know about content blocks.

Multi-line input with Cmd+Enter to send, Shift+Enter for newline, queued sends while a turn is in flight, and a stop control wired to the abort protocol. The composer is where most of the chat polish lives.

An `update_tools` message rebinds the agent's available tools mid-session when the controlled tab changes. Avoided tearing down and reissuing tickets on every navigation.

Pydantic model for external GraphQL profile data with camelCase aliasing, provider extraction, and reasoning-effort validation. Removed `dict[str, Any]` from the agent boundary.

Origin-bound, hashed-key tickets with 60s TTL and atomic consume. Replaced JWT-in-query-param auth, which would have leaked tokens through extension logs.

Modules register and unregister tools at runtime through a `(name, definition, implementation)` signature. CDP tools, tab access, and content capture all live behind the same interface.

Mongo-backed checkpoint saver scoped by `conversation_id`. After an abort, the next turn starts from the last persisted message, not from a fresh transcript.

Cmd+K (and Cmd+Shift+O) opens three modes: new chat, settings, and search. Relative date labels, request deduplication so stale results don't overwrite fresh ones.

Bun script generates a new feature module's directory shape, adds it to the toggle registry, and validates kebab-case naming. Stops new features from drifting in shape.

Local-only flags (tool debug, SSE inspector) and always-on flags (suggestions, agent config) in one registry. Persists to localStorage; a settings tab exposes them with friendly names.

Search by title and message content with cursor pagination. Orchestration lives in a use case, not the repository, so the query path stays under domain control.

Date-grouped conversation list, rename and delete inline, optimistic updates, loading skeletons. Built on shadcn primitives so it matches the rest of the chrome.

Buffers keystroke-rate text deltas and flushes them once per frame. Keeps the chat smooth under streaming load and stabilises the order of multi-tool turns.

Tells Streamdown to short-circuit re-renders mid-token-stream and only do a final pass when the turn finishes. Removed the worst of the message-list jank.

Distinct `SubagentStart`, `SubagentTextDelta`, and `SubagentToolCallStart` events let the frontend show delegated work without conflating it with the parent turn's tokens.

Collapsible per-tool panel with a shimmer running state, a special web-search affordance, and a consolidated row when several tools fire in parallel. Replaced an early one-line spinner.

AppContainer manages tool registry, LLM factory, agent service, and session services with lazy initialization. Replaced module-level singletons so tests no longer have to monkey-patch globals.

Ownership filter pushed into the query, not layered on after, so a missing scope can't leak data. Safe-delete ordering and request-scoped checks fell out of the same pass.

Streams keep going when the tab loses focus, and results re-attach when the user comes back. Closes the loop where a long browser-tool turn used to look stuck.

Domain entities, use cases, protocols, repositories, and presentation schemas wired through a single DI module. The split paid off when middleware, subagents, and providers slotted into existing seams without rewriting the API.

Forces a specific tool when the product needs it, by mutating LangGraph's `tool_choice` between turns. LangChain's built-in selector solves a different problem (filtering visible tools), so I wrote this layer.

Each feature owns its module/, components/, hooks/, lib/, and __tests__/. A small create-feature script enforces the shape so new features always look the same.

Text deltas, tool calls, tool results, token usage, finish reason, and disconnect signals. Designed against the contract, not the LangChain emitter, so the frontend code is portable across providers.

abortKey-keyed registry with AbortError handled gracefully. The stop button, route changes, and reload all converge on the same path so partial responses don't get orphaned.

Composable layers (DynamicToolChoice, ToolMonitor, SubAgent, prompt context) instead of subclassing the agent. Each middleware is independently testable and addable.

Avoids reconnecting to the upstream provider on every turn, which was the dominant tail-latency source under streaming load.

Request-scoped resolution of OpenAI, Anthropic, and Google credentials, with a model allowlist per provider. Each agent run uses the right user's keys without any global config.

Auto-memoisation in production builds and a Vite chunking pass that keeps the streaming hot path off the cold path. Smaller, cache-friendlier bundles.

Literal unions enforce OpenAI and LangChain spec compliance at the type level. Removed a class of `KeyError`s that only surfaced at LLM call time.

Reused middleware across requests instead of reconstructing them per turn. Combined with lazy SubAgentMiddleware init, this cut the streaming hot path significantly.

Replaced vanilla markdown with Streamdown plus the code plugin. Streaming-aware, doesn't reflow on every token, and code blocks finally look right under heavy delta load.

Ephemeral subagents share the parent's tool registry and streaming protocol, so the frontend only needs to know about one event shape. Lazy init keeps the cold path quiet.

Axios instance with `X-Tenant-ID`/`X-User-ID` headers, EAB-extension token fetch, and 401 retry. The rest of the app talks to one client, not five.

User cancellation, request scope, and upstream provider abort wired together. OpenAI streaming cancellation isn't actually feasible through LangChain's adapter, so I documented that and made sure partial responses still persist.