docs: Effect-first README with install and API reference

Leads with the Effect angle — the gap this plugin fills in the nvim
ecosystem is turning `Effect<A, E, R>` assignability errors from
unreadable one-line tooltips into channel-aware diff boxes.

Documents:
- Motivating example (the Missing Services box)
- Feature list split into Effect-specific and general TS sections
- lazy.nvim install recipe + manual wiring snippet
- Integration snippet for tiny-inline-diagnostic
- Config options table
- Public API reference
- Extension example via `extra_patterns`
- How to run the tests locally

Author: rashedInt32

README.md

@@ -0,0 +1,158 @@
+# effect-error-pretty.nvim
+
+Effect-first TypeScript diagnostic formatter for Neovim. Turns walls of `Effect<A, E, R>` assignability errors into something you can actually read — with dedicated handling for the Effect ecosystem's pain points.
+
+TypeScript errors in general also get the treatment, but Effect is the headline act.
+
+## Why
+
+When you're learning Effect, half the type errors look like this:
+
+```
+Type 'Effect<void, DbError, Database | Logger>' is not assignable to type 'Effect<void, DbError, never>'.
+```
+
+VSCode and Zed render that as one wrapped line in a tooltip. The actual information — "you forgot to provide `Database | Logger`" — is buried.
+
+This plugin parses the error, figures out which channel (A, E, or R) actually diverged, and renders:
+
+```
+╭─ ◈ Effect — Missing Services
+│
+│  ◈ Forgot to provide: Database | Logger
+│  ⚡ Hint: .pipe(Effect.provide(SomeLayer))
+│
+│  Got:      Effect<void, DbError, Database | Logger>
+│  Expected: Effect<void, DbError, never>
+╰─
+```
+
+## Features
+
+**Effect-specific**
+- `Effect<A, E, R>` / `Effect.Effect<A, E, R>` / `Stream<A, E, R>` / `Layer<ROut, E, RIn>` — all parsed, channel-labeled, and diffed
+- **Missing services** (forgot `Effect.provide`) — compact box naming the exact services
+- **Unhandled errors** (forgot `Effect.catchAll` / `catchTags` / `orDie`) — compact box listing the leftover `E` members
+- **Wrong success type** — compact box with Got/Expected for `A` (or `ROut` for Layer)
+- **Scope-required** — detects `Scope` in got.R and suggests `Effect.scoped`
+- **`Context.Tag<"Id", Service>` unwrapping** — shows just the service name in diffs
+- **`YieldWrap<...>` unwrapping** — Effect.gen yields render as plain Effect mismatches
+- **Short signatures** — `Effect<A>` and `Effect<A, E>` default missing params to `never`
+- **Multi-channel view** — falls back to a full tri-channel table when 2+ channels diverge
+- **Type signature at the bottom** of every compact box so you see the full `Effect<...>` context
+
+**General TypeScript**
+- Type mismatches (TS2322 / TS2345) with multi-line wrapping for big types
+- Missing property (TS2741), Unknown property (TS2339)
+- Cannot find name / module / exported member (TS2304 / TS2307 / TS2305)
+- Implicit any (TS7006), Uninitialized variable (TS2454), Nullish (TS2531 / TS18048)
+- Argument count (TS2554), Const reassignment, Not callable (TS2349)
+- Deprecated symbol messages
+- Optional fallback to [`format-ts-errors`](https://www.npmjs.com/package/@0no-co/format-ts-errors) when no pattern matches
+
+## Install
+
+Requires Neovim 0.10+.
+
+### lazy.nvim
+
+```lua
+{
+  "rashedInt32/effect-error-pretty.nvim",
+  event = { "BufReadPre", "BufNewFile" },
+  opts = {
+    float = true,          -- auto-patch vim.diagnostic.config.float.format
+    effect = true,
+    format_ts_errors_fallback = true,
+  },
+}
+```
+
+### Manual wiring
+
+If you manage `vim.diagnostic.config` yourself, don't set `float = true`. Call the formatter directly:
+
+```lua
+local pretty = require("effect-error-pretty")
+pretty.setup({ effect = true })
+
+vim.diagnostic.config({
+  float = {
+    format = function(diagnostic)
+      return pretty.float_format(diagnostic) or diagnostic.message
+    end,
+  },
+})
+```
+
+### tiny-inline-diagnostic.nvim
+
+```lua
+{
+  "rachartier/tiny-inline-diagnostic.nvim",
+  opts = {
+    options = {
+      format = function(diagnostic)
+        return require("effect-error-pretty").inline_format(diagnostic) or diagnostic.message
+      end,
+    },
+  },
+}
+```
+
+## Options
+
+| Option                       | Default | Description                                                                                               |
+|------------------------------|---------|-----------------------------------------------------------------------------------------------------------|
+| `effect`                     | `true`  | Recognize `Effect` / `Stream` / `Layer` mismatches as first-class.                                        |
+| `float`                      | `false` | Automatically patch `vim.diagnostic.config.float.format` on `setup()`.                                    |
+| `sources`                    | `{ typescript=true, ts=true, vtsls=true }` | Diagnostic sources this plugin handles. Exact match only. |
+| `format_ts_errors_fallback`  | `true`  | When no pattern matches, try `format-ts-errors` if installed.                                             |
+| `extra_patterns`             | `nil`   | List of `function(msg) -> {kind, ...}` parsers run after builtins. Let you add custom shapes.              |
+
+## Public API
+
+```lua
+local pretty = require("effect-error-pretty")
+
+-- Float box (multi-line) — returns nil if unhandled; caller should fall back.
+pretty.float_format(diagnostic)
+
+-- Inline one-line — returns nil if unhandled.
+pretty.inline_format(diagnostic)
+
+-- Low-level: parse a raw TS diagnostic message into a structured kind.
+-- Returns nil if no pattern matched.
+require("effect-error-pretty.parse").parse(message, { effect = true })
+```
+
+## Extending
+
+Add a parser for a custom rule you care about:
+
+```lua
+require("effect-error-pretty").setup({
+  extra_patterns = {
+    function(msg)
+      local rule = msg:match("^eslint%-plugin%-effect: (.+)$")
+      if rule then
+        return { kind = "custom_lint", rule = rule }
+      end
+    end,
+  },
+})
+```
+
+Render logic for custom `kind`s isn't wired in yet — for now, `parse()` returns the structured result and you render it yourself. If there's demand, we'll expose a renderer registry.
+
+## Tests
+
+```sh
+nvim --headless -c "PlenaryBustedDirectory tests/" -c "qa!"
+```
+
+Requires [plenary.nvim](https://github.com/nvim-lua/plenary.nvim) on the runtimepath.
+
+## License
+
+MIT