Enable Elixir tracking and update .gitignore

- Add .gitattributes for Elixir file tracking. - Extend .gitignore for Elixir-related and other development files. -
Introduce Agents.md with project guidelines and usage rules. - Create CLAUDE.md as a symlink to Agents.md. - Update
mix.exs to specify proper version for elixir_sense.

.gitattributes

@@ -0,0 +1,3 @@
+# Cicada: Enable git function tracking for Elixir
+*.ex diff=elixir
+*.exs diff=elixir

.gitignore

@@ -1,3 +1,19 @@
+# Development artefacts
+.DS_Store
+.vscode
+.drone.status
+
+# Elixir LS and Tools
+.elixir_ls
+.elixir-tools
+.lexical
+.expert
+
+# AI tools
+.claude
+.codex
+.mcp.json
+
 # The directory Mix will write compiled artifacts to.
 /_build/
 

Agents.md

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+This is a web application written using the Phoenix web framework.
+
+## Project guidelines
+
+- Use `mix check` alias when you are done with all changes and fix any pending issues
+- Use the already included and available `:req` (`Req`) library for HTTP requests, **avoid** `:httpoison`, `:tesla`, and `:httpc`. Req is included by default and is the preferred HTTP client for Banker
+- Use the already included and available Elixir native JSON module to encode and decode JSON, **avoid** `:jason`, `:poison`, and other. JSON is a part of Elixir standard library and is the preferred JSON parser and generator for Banker
+
+<!-- elixir-toolkit-commands--execution-start -->
+
+## Command Execution
+
+**🔴 CRITICAL: ALWAYS prefix mix, iex commands with environment variables:**
+
+**For Development:**
+```bash
+env $(cat .dev.env | xargs) mix <COMMAND>
+env $(cat .dev.env | xargs) iex -S mix
+```
+
+**For Testing:**
+```bash
+env $(cat .test.env | xargs) mix test
+env $(cat .test.env | xargs) iex -S mix
+```
+
+**Examples:**
+```bash
+# Development
+env $(cat .dev.env | xargs) mix test
+env $(cat .dev.env | xargs) mix compile
+env $(cat .dev.env | xargs) mix phx.server
+
+# Testing
+env $(cat .test.env | xargs) mix test
+env $(cat .test.env | xargs) mix test test/banker/assistants/invoice_data_assistant_test.exs
+env $(cat .test.env | xargs) iex -S mix
+```
+
+**NEVER run mix commands without the appropriate ENV file prefix** - will fail with missing ENV variable errors.
+- Use `.dev.env` for development commands
+- Use `.test.env` for test commands
+
+
+<!-- elixir-toolkit-commands--execution-end -->
+
+<!-- tool-usage-start -->
+## Tool Usage Guidelines
+
+<!-- tool-usage:code-start -->
+### Code base analysys and semantic code search
+
+Register project to make Tree Sitter tool available for analyzing the Banker codebase and get next posibilities: 
+
+- **Search codebase**: Find files, functions, or patterns
+- **Understand architecture**: Explore modules, domains, resources
+- **Code navigation**: Jump to definitions, find usages
+- **Quality analysis**: Detect complexity, duplication, dependencies
+- **Strategic exploration**: Understand domain structure and relationships
+
+**Always use tree_sitter_banker tool** for: 
+
+  1. **Code Navigation**: Extract functions, classes, modules. Find where symbols are used. Search with regex patterns. Read file contents efficiently. Get abstract syntax trees
+  2. **Analysis Tools**: Measure cyclomatic complexity. Find imports and dependencies. Detect code duplication. Execute tree-sitter queries
+  3. **Project Understanding**: Get file lists by pattern or extension. Analyze project structure. Get file metadata and line counts. Navigate dependencies.
+
+<!-- tool-usage:code-end -->
+
+<!-- tool-usage:documentation-start -->
+### Documentation
+- **Always use HEXDocs tool** to get and analyze **actual documentation** for Elixir, Elixir libraries and Phoenix framework
+<!-- tool-usage:documentation-end -->
+
+<!-- tool-usage:database-start -->
+### Database Access
+- **Use only** postgres_banker_dev tool to comunicate with development database
+- **Use only** postgres_banker_test tool to comunicate with test database
+- **Only in case when** postgres_banker_dev or postgres_banker_test tools is unavaliable you can get data from databases directly:
+  - Development database: `psql banker_dev -c "<query>"`
+  - Test database: `psql banker_test -c "<query>"`
+- **NEVER** try do anything with production database. You are **FORBIDDEN** from execute any queries on prod environmemnt
+<!-- tool-usage:database-end -->
+
+<!-- tool-usage-end -->
+
+<!-- guidelines-start -->
+
+<!-- guidelines:elixir-start -->
+## Elixir Core Usage Rules
+
+### Pattern Matching
+- Use pattern matching over conditional logic when possible
+- Prefer to match on function heads instead of using `if`/`else` or `case` in function bodies
+- `%{}` matches ANY map, not just empty maps. Use `map_size(map) == 0` guard to check for truly empty maps
+
+### Error Handling
+- Use `{:ok, result}` and `{:error, reason}` tuples for operations that can fail
+- Avoid raising exceptions for control flow
+- Use `with` for chaining operations that return `{:ok, _}` or `{:error, _}`
+
+### Common Mistakes to Avoid
+- Elixir has no `return` statement, nor early returns. The last expression in a block is always returned.
+- Don't use `Enum` functions on large collections when `Stream` is more appropriate
+- Avoid nested `case` statements - refactor to a single `case`, `with` or separate functions
+- Don't use `String.to_atom/1` on user input (memory leak risk)
+- Lists and enumerables cannot be indexed with brackets. Use pattern matching or `Enum` functions
+- Prefer `Enum` functions like `Enum.reduce` over recursion
+- When recursion is necessary, prefer to use pattern matching in function heads for base case detection
+- Using the process dictionary is typically a sign of unidiomatic code
+- Only use macros if explicitly requested
+- There are many useful standard library functions, prefer to use them where possible
+- **Never** nest multiple modules in the same file as it can cause cyclic dependencies and compilation errors
+
+### Function Design
+- Use guard clauses: `when is_binary(name) and byte_size(name) > 0`
+- Prefer multiple function clauses over complex conditional logic
+- Name functions descriptively: `calculate_total_price/2` not `calc/2`
+- Predicate function names should not start with `is` and should end in a question mark.
+- Names like `is_thing` should be reserved for guards
+
+### Data Structures
+- Use structs over maps when the shape is known: `defstruct [:name, :age]`
+- Use maps for dynamic key-value data
+- **Never** use map access syntax (`changeset[:field]`) on structs as they do not implement the Access behaviour by default. For regular structs, you **must** access the fields directly, such as `my_struct.field` or use higher level APIs that are available on the struct if they exist, `Ecto.Changeset.get_field/2` for changesets
+- Elixir's standard library has everything necessary for date and time manipulation. Familiarize yourself with the common `Time`, `Date`, `DateTime`, and `Calendar` interfaces by accessing their documentation as necessary. **Never** install additional dependencies unless asked or for date/time parsing (which you can use the `date_time_parser` package)
+- Don't use `String.to_atom/1` on user input (memory leak risk)
+- Predicate function names should not start with `is_` and should end in a question mark. Names like `is_thing` should be reserved for guards
+- Elixir's builtin OTP primitives like `DynamicSupervisor` and `Registry`, require names in the child spec, such as `{DynamicSupervisor, name: Banker.MyDynamicSup}`, then you can use `DynamicSupervisor.start_child(Banker.MyDynamicSup, child_spec)`
+- Use `Task.async_stream(collection, callback, options)` for concurrent enumeration with back-pressure. The majority of times you will want to pass `timeout: :infinity` as option
+- Elixir variables are immutable, but can be rebound, so for block expressions like `if`, `case`, `cond`, etc
+  you *must* bind the result of the expression to a variable if you want to use it and you CANNOT rebind the result inside the expression, ie:
+
+      # INVALID: we are rebinding inside the `if` and the result never gets assigned
+      if connected?(socket) do
+        socket = assign(socket, :val, val)
+      end
+
+      # VALID: we rebind the result of the `if` to a new variable
+      socket =
+        if connected?(socket) do
+          assign(socket, :val, val)
+        end
+- Prefer keyword lists for options: `[timeout: 5000, retries: 3]`
+- Prefer to prepend to lists `[new | list]` not `list ++ [new]`
+- Elixir lists **do not support index based access via the access syntax**
+
+  **Never do this (invalid)**:
+
+      i = 0
+      mylist = ["blue", "green"]
+      mylist[i]
+
+  Instead, **always** use `Enum.at`, pattern matching, or `List` for index based list access, ie:
+
+      i = 0
+      mylist = ["blue", "green"]
+      Enum.at(mylist, i)
+
+
+### Mix Tasks
+
+- Use `mix help` to list available mix tasks
+- Use `mix help task_name` to get docs for an individual task
+- Read the docs and options before using tasks (by using `mix help task_name`)
+- To debug test failures, run tests in a specific file with `mix test test/my_test.exs` or run all previously failed tests with `mix test --failed`
+- `mix deps.clean --all` is **almost never needed**. **Avoid** using it unless you have good reason
+
+### Testing
+- Run tests in a specific file with `mix test test/my_test.exs` and a specific test with the line number `mix test path/to/test.exs:123`
+- Limit the number of failed tests with `mix test --max-failures n`
+- Use `@tag` to tag specific tests, and `mix test --only tag` to run only those tests
+- Use `assert_raise` for testing expected exceptions: `assert_raise ArgumentError, fn -> invalid_function() end`
+- Use `mix help test` to for full documentation on running tests
+
+### Debugging
+
+- Use `dbg/1` to print values while debugging. This will display the formatted value and other relevant information in the console.
+
+<!-- guidelines:elixir-end -->
+
+<!-- guidelines:otp-start -->
+## OTP Usage Rules
+
+### GenServer Best Practices
+- Keep state simple and serializable
+- Handle all expected messages explicitly
+- Use `handle_continue/2` for post-init work
+- Implement proper cleanup in `terminate/2` when necessary
+
+### Process Communication
+- Use `GenServer.call/3` for synchronous requests expecting replies
+- Use `GenServer.cast/2` for fire-and-forget messages.
+- When in doubt, use `call` over `cast`, to ensure back-pressure
+- Set appropriate timeouts for `call/3` operations
+
+### Fault Tolerance
+- Set up processes such that they can handle crashing and being restarted by supervisors
+- Use `:max_restarts` and `:max_seconds` to prevent restart loops
+
+### Task and Async
+- Use `Task.Supervisor` for better fault tolerance
+- Handle task failures with `Task.yield/2` or `Task.shutdown/2`
+- Set appropriate task timeouts
+- Use `Task.async_stream/3` for concurrent enumeration with back-pressure
+
+<!-- guidelines:otp-end -->
+
+<!-- guidelines-end -->
+
+<cicada>
+  **ALWAYS use cicada-mcp tools for Elixir and Python code searches. NEVER use Grep/Find for these tasks.**
+
+  ### Use cicada tools for:
+  - YOUR PRIMARY TOOL - Start here for ALL code exploration and discovery. `mcp__cicada__query`
+  - DEEP-DIVE TOOL: View a module's complete API and dependencies after discovering it with query. `mcp__cicada__search_module`
+  - DEEP-DIVE TOOL: Find function definitions and call sites after discovering with query. `mcp__cicada__search_function`
+  - UNIFIED HISTORY TOOL: One tool for all git history queries - replaces get_blame, get_commit_history, find_pr_for_line, and get_file_pr_history. `mcp__cicada__git_history`
+  - ANALYSIS TOOL: Find potentially unused public functions with confidence levels. `mcp__cicada__find_dead_code`
+  - DRILL-DOWN TOOL: Expand a query result to see complete details. `mcp__cicada__expand_result`
+  - ADVANCED: Execute jq queries directly against the Cicada index for custom analysis and data exploration. `mcp__cicada__query_jq`
+
+  ### DO NOT use Grep for:
+  - ❌ Searching for module structure
+  - ❌ Searching for function definitions
+  - ❌ Searching for module imports/usage
+
+  ### You can still use Grep for:
+  - ✓ Non-code files (markdown, JSON, config)
+  - ✓ String literal searches
+  - ✓ Pattern matching in single line comments
+</cicada>
+

CLAUDE.md

@@ -0,0 +1 @@
+./Agents.md

mix.exs

@@ -69,10 +69,7 @@ defp deps do
       {:sobelow, ">= 0.0.0", only: ~w(dev test)a, runtime: false},
       {:mix_audit, ">= 0.0.0", only: ~w(dev test)a, runtime: false},
       {:observer_cli, "~> 1.7.4", only: :dev, runtime: false},
-      {:elixir_sense, github: "elixir-lsp/elixir_sense", only: ~w(dev)a}
+      {:elixir_sense, "~> 1.0.0", only: :dev}
-
-      # {:dep_from_hexpm, "~> 0.3.0"},
-      # {:dep_from_git, git: "https://github.com/elixir-lang/my_dep.git", tag: "0.1.0"}
     ]
   end
 end