Introducing Coline Tab

What is Coline Tab?

When you're writing emails, notes, documentation, or managing tasks, your flow matters. Context switching kills productivity. Waiting for suggestions breaks your rhythm. That's why we built Coline Tab, an AI autocomplete system that predicts what you're about to type and delivers it faster than you can blink.

Most autocomplete tools give you one thing or the other: either they're fast with terrible suggestions, or smart but laggy. Cursor Tab is excellent, fast and intelligent, but it only works in the Cursor IDE. We built Coline Tab because we needed that same power everywhere: in emails, notes, issues, calendar events, and across your entire productivity workspace. It understands context, picks up on patterns, and streams suggestions before you've finished thinking them.

The Problem: Speed vs. Intelligence

Autocomplete has always forced developers into a frustrating choice: fast or smart, pick one. GitHub Copilot has delivered solid suggestions since Codex launched in 2023, but the 200-500ms latency breaks your flow. They finally shipped their own model just two weeks ago to improve this, though they're still behind Cursor. Cursor and Supermaven nailed the speed-intelligence problem, giving you both instant responses and smart suggestions right in your IDE. Traditional autocomplete is fast but dumb. It has no idea what you're actually trying to build.

We refused to accept this compromise. Coline Tab delivers both lightning-fast responses and intelligent, context-aware suggestions everywhere you work.

How We Built It

Our Tab Model

We tested dozens of models: GPT-4o Mini, Gemini Flash Lite, Llama 3.1 via Groq, and more. Most were either too slow, too expensive, or hallucinated too much, especially Llama. So we built our own Tab model ourselves, an in-house distilled transformer tuned for ultra-fast autocomplete.

Our Tab model is optimized for speed and accuracy, producing predictions in milliseconds while staying anchored to your context.

The Delivery

Autocomplete only feels instant if the first token shows up almost immediately. Coline Tab streams completions over Server-Sent Events (SSE), a lean one-way channel that skips the persistent heartbeat overhead of WebSockets. We open a single HTTP connection and then emit tokens as a continuous event stream with the first token in about <25ms, with the remainder pipelined so you can accept part of a suggestion while the tail is still generating. If a network hiccup occurs we transparently retry with jittered backoff.

We chose SSE for its simplicity, HTTP/2 multiplexing, and easy CDN handling of short bursts. When we need bi-directional control (e.g. cancel), we send a lightweight abort request on a separate endpoint, keeping the stream itself pure and fast.

The Intelligence

Coline is an all-in-one productivity platform, so Coline Tab has to feel natural whether you're polishing lines of code, drafting an email, logging an issue, or jotting a note for next week's planning. Instead of treating everything like plain text, it quietly reads the room: what kind of surface you're in, what you've written so far, and the patterns you personally lean toward.

We keep it simple on the outside and purposeful under the hood. Tab:

• Adapts to the surface: Code, markdown, or plain text each get suggestions that match their style and formatting.
• Understands the task: A meeting note feels different from a bug report. Suggestions reflect the intent of where you're writing.
• Learns from you: It picks up tone, naming habits, and how verbose or concise you tend to be, and then mirrors it.

The result is prediction that feels less like a generic AI and more like a teammate finishing your thought everywhere inside Coline.

The Memory

Generating completions from scratch every time would be wasteful. Instead, Coline Tab uses a multi-layer semantic cache with LRU (Least Recently Used) eviction:

• Exact match cache: If you've typed this exact context before, we return the cached suggestion instantly.
• Semantic similarity cache: Even if the text differs slightly, we use similarity matching (0.6-0.8 threshold) to find relevant cached suggestions.
• Rejected suggestion tracking: We remember what you rejected and never show it again.
• Cache validation: Quality filters ensure only high-confidence suggestions are cached.

The Timing

We don't want to spam the API with every keystroke, but we also don't want to wait too long. Coline Tab uses adaptive debouncing based on your typing speed:

This means if you're blazing through code, suggestions appear almost instantly. If you pause to think, we give you space, then respond the moment you start typing again.

The Format: Multi-line Suggestions

Most autocompletes only suggest single lines. Coline Tab supports up to 10 lines of intelligent, formatted suggestions:

• Smart indentation: Detects whether you use spaces or tabs, and how many (2, 4, 8 spaces).
• Line break intelligence: Suggests breaks at sentence boundaries, list items, code blocks, etc.
• Markdown awareness: Understands headings, lists, quotes, code fences, and formats suggestions accordingly.
• Code block formatting: Properly indents nested code structures (functions, classes, loops).

The Experience

Great autocomplete should feel like reading your mind. We achieve this through:

Visual Feedback

• Confidence-based UI: High-confidence suggestions appear more solid, uncertain ones are more transparent.
• Color tinting: Green for high confidence, purple for medium, yellow for lower. Subtle visual cues without distraction.

This helps you gauge how much to trust a suggestion at a glance, and all of this is changable in settings.

Flexible Acceptance

You're in control. Tab offers multiple ways to accept suggestions:

• Tab - Accept the full suggestion
• → - Accept the next character
• Ctrl + → - Accept the next word
• Ctrl + ↵ - Accept to the next line
• Esc - Reject the suggestion

Smart Validation

Not all suggestions are worth showing. We filter out:

• Repetitive suggestions (same text over and over)
• Overlapping text (suggesting what's already typed)
• Previously rejected suggestions (it learns from your rejections)
• Low-confidence hallucinations
• Only shows meaningful continuations that add value

Data & Privacy

Tab learns from how you interact with suggestions, but it does so with your privacy at the center. We collect a small set of privacy-safe signals to help us tune speed, relevance, and future RLHF improvements, but never full document contents or private workspace data.

What we capture:

• Latency + performance: When a request starts and when the first token arrives.
• Suggestion lifecycle: Whether a suggestion was shown, accepted fully, accepted partially (character / word / line), ignored, or rejected.
• Basic shape: Anonymous length, number of lines, and a hashed fingerprint (for dedup + cache tuning).
• Error + retry data: To spot instability and fix it fast.

What we do not store for training:

• Full email, note, issue, card, or calendar content.
• Secrets like API keys, tokens, passwords. Automated scanners drop obvious matches immediately.
• Personally identifying text (names, emails) beyond transient in-memory processing.

For RL training, we convert your interactions into lightweight reward signals: accept = positive, partial accept = scaled positive, reject = negative, ignore = neutral. These are aggregated and detached from your account before model tuning. Occasional sample snippets (truncated to a small window) may be briefly queued for automated quality checks, then purged. They never enter long-term storage if they trip a redaction rule.

You can toggle advanced telemetry in Settings at any time. Even with everything off, Tab still works, just with fewer personalized improvements. For details, see our Privacy Policy.

Available Everywhere

Wherever you type inside Coline, whether it be emails, notes, issues, cards, calendar events, todos, planning docs, and more, Coline Tab is quietly active. No mode switching or separate install; the same fast, context-aware suggestions follow you across the entire workspace so your flow never fractures.