feat: support string login in build_config and add substitute_mapping_values (#63)

* feat: support string login in build_config and add substitute_mapping_values (#61, #62)

Extend build_config() to accept login: int | str | None. String logins
are coerced via the existing coerce_login() helper (empty/whitespace →
None, numeric strings → int, non-numeric → ValueError). When
allow_whole_dollar_env=True, ${ENV} and $ENV placeholders are expanded
before coercion, consistent with path/password/server behavior.

Add substitute_mapping_values(), a generic recursive helper that
substitutes environment placeholders in nested dicts/lists only for
caller-selected mapping keys. Non-selected fields (including literal
dollar signs) are preserved exactly. Supports blank_string_keys_as_none
to normalise empty strings to None after substitution. No application-
specific key names (e.g. mt5_login) are hard-coded in mt5cli.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* Bump version to v0.9.5

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* docs+test: clarify substitute_mapping_values docstring and pin tuple behaviour

- Adds sentence noting list-element strings are never substituted (only
  immediate dict values are), addressing reviewer finding #1.
- Rewrites Returns section to accurately describe scalar pass-through
  behaviour, addressing reviewer finding #2.
- Adds recursion-depth caveat to the generic-utility docstring,
  addressing reviewer finding #4.
- Adds test_tuple_container_not_traversed to pin the existing silent
  tuple-exclusion contract, addressing reviewer finding #3.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* docs: update public contract and README for build_config login coercion and substitute_mapping_values

- Expands build_config row to document login: int | str | None,
  numeric-string coercion, blank-string handling, and env placeholder
  expansion when allow_whole_dollar_env=True.
- Adds substitute_mapping_values to the stable SDK table with a note
  that key names are never hard-coded in mt5cli.
- Extends allow_whole_dollar_env paragraph to list substitute_mapping_values.
- README: adds build_config env-placeholder example and imports to the
  trading lifecycle snippet.
- README: extends credential-resolution bullet with a substitute_mapping_values
  usage example using generic key names.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

---------

Co-authored-by: agent <agent@localhost>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

README.md

@@ -31,7 +31,7 @@ pip install -U mt5cli MetaTrader5
 
 ## Python API (downstream packages)
 
-Import `MT5Client` for generic MT5 data access, schema normalization, and optional order primitives. `Mt5CliClient` remains available as a backward-compatible alias.
+Import `MT5Client` for generic MT5 data access, schema normalization, and optional order primitives.
 
 ```python
 from datetime import UTC, datetime
@@ -92,16 +92,21 @@ Schema contracts live in `mt5cli.schemas` (`DataKind`, `validate_schema`, `norma
 Trading applications can depend on `mt5cli` imports only; terminal path,
 credentials, server, and timeout are forwarded to `pdmt5.Mt5Config`, numeric
 login strings are coerced to integers, and empty login strings are treated as
-unset.
+unset. Pass `allow_whole_dollar_env=True` to expand `${ENV_VAR}` and bare
+`$ENV_NAME` placeholders in connection string parameters before coercion.
 
 ```python
 from mt5cli import (
+    build_config,
     calculate_spread_ratio,
     create_trading_client,
     get_account_snapshot,
     mt5_trading_session,
 )
 
+# Login from environment — numeric string is coerced to int automatically
+config = build_config(login="$MT5_LOGIN", allow_whole_dollar_env=True)
+
 with mt5_trading_session(
     path=r"C:\Program Files\MetaTrader 5\terminal64.exe",
     login="12345",
@@ -248,9 +253,9 @@ rates = collect_latest_closed_rates_by_granularity(
 eurusd_m1 = rates["EURUSD", "M1"]  # closed bars only
 ```
 
-- **Credential resolution**: use `resolve_account_spec()` / `resolve_account_specs()` to merge explicit override values over `AccountSpec` fields and expand `${ENV_VAR}` placeholders (via `substitute_env_placeholders()`), raising `ValueError` for missing variables. This keeps secrets out of plan/config files without coupling to any strategy code.
+- **Credential resolution**: use `resolve_account_spec()` / `resolve_account_specs()` to merge explicit override values over `AccountSpec` fields and expand `${ENV_VAR}` placeholders (via `substitute_env_placeholders()`), raising `ValueError` for missing variables. This keeps secrets out of plan/config files without coupling to any strategy code. For config dicts or nested structures loaded from YAML/TOML, use `substitute_mapping_values(data, keys={"login", "password"})` to expand placeholders only for caller-specified keys — key names are never hard-coded in mt5cli.
 - **Throttled history updates**: use `ThrottledHistoryUpdater` to wrap `update_history()` with a minimum `interval_seconds` between successful runs (monotonic clock). Call `should_update()` / `update(client, symbols)` from an application loop; errors propagate by default, or pass `suppress_errors=True` to swallow recoverable `Mt5*Error`, `sqlite3.Error`, `ValueError`, `OSError`, and MT5 client capability errors for history API methods without advancing the throttle (other `AttributeError` / `TypeError` values always propagate). Pass `update_backend` to inject a custom history update callable (same keyword arguments as `update_history`) instead of monkey-patching `mt5cli.sdk.update_history`.
-- **Trading session helpers**: use `mt5_trading_session()` for a trading-capable `pdmt5.Mt5TradingClient` that initializes/logs in via `Mt5Config.path` and always shuts down safely. Pair with `detect_position_side()`, `calculate_margin_and_volume()`, and `determine_order_limits()` for generic position and sizing utilities. The read-only `mt5_session()` / `Mt5CliClient` SDK is unchanged.
+- **Trading session helpers**: use `mt5_trading_session()` for a trading-capable `pdmt5.Mt5TradingClient` that initializes/logs in via `Mt5Config.path` and always shuts down safely. Pair with `detect_position_side()`, `calculate_margin_and_volume()`, and `determine_order_limits()` for generic position and sizing utilities. Keep read-only collection on `mt5_session()` / `MT5Client`.
 - **Granularity-keyed rate loading**: `load_rate_series_by_granularity()` builds targets with `build_rate_targets()`, loads them with `load_rate_series_from_sqlite()`, and returns a mapping keyed by `(symbol | None, granularity_name)` such as `("EURUSD", "M1")` to reduce downstream boilerplate.
 - **MT5 session helper**: use the `mt5_session()` context manager to attach to (or, when `Mt5Config.path` is set, launch) an MT5 terminal, log in, and yield a connected `MT5Client` that shuts down on exit.
 - **SQLite export helpers**: use `export_dataframe_to_sqlite()` for append mode, optional index export, and post-write deduplication by key columns.
@@ -317,7 +322,7 @@ finally:
     client.shutdown()
 ```
 
-Read-only collectors can keep using `mt5_session()` and `MT5Client` (or the `Mt5CliClient` alias) without changes.
+Read-only collectors can keep using `mt5_session()` and `MT5Client`.
 
 ## Development
 

docs/api/public-contract.md

@@ -8,55 +8,49 @@ downstream app -> mt5cli -> pdmt5 -> MetaTrader 5
 ```
 
 Downstream packages should import from the package root (`from mt5cli import
-...`) and treat the symbols listed below as the stable SDK contract. CLI
-commands mirror the same behavior but are not importable Python APIs.
+...`) and use the public tier sets in `mt5cli.contract` to distinguish API
+stability. CLI commands mirror the same behavior but are not importable Python
+APIs.
+
+## Public API tiers
+
+mt5cli classifies package-root imports by intended downstream use:
+
+| Tier             | Contract set               | Meaning                                                                                                                                     |
+| ---------------- | -------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------- |
+| Stable core      | `STABLE_SDK_EXPORTS`       | Preferred SDK surface for downstream MT5 infrastructure adapters. Changes require a deliberate compatibility path.                          |
+| Secondary public | `SECONDARY_PUBLIC_EXPORTS` | Public helpers for CLI/export/schema integrations and lower-level MT5 wrappers. Importable, but less central to the downstream trading SDK. |
 
 ## Stable downstream SDK API
 
 These names are exported from `mt5cli` and covered by the contract in
-`mt5cli.STABLE_SDK_EXPORTS` (defined in `mt5cli.contract`). Prefer `MT5Client` over the legacy `Mt5CliClient`
-alias for new code.
+`mt5cli.STABLE_SDK_EXPORTS` (defined in `mt5cli.contract`).
 
 ### Session lifecycle and configuration
 
-| Symbol                                          | Role                                                                                                       |
-| ----------------------------------------------- | ---------------------------------------------------------------------------------------------------------- |
-| `MT5Client`, `Mt5CliClient`                     | Read-only data client with optional `order_check` / `order_send`                                           |
-| `build_config`                                  | Build `pdmt5.Mt5Config` from connection fields                                                             |
-| `mt5_session`                                   | Context manager: initialize, login, yield client, shutdown                                                 |
-| `create_trading_client`, `mt5_trading_session`  | Trading-capable `pdmt5.Mt5TradingClient` lifecycle                                                         |
-| `AccountSpec`                                   | Generic account group: symbols plus optional credentials                                                   |
-| `resolve_account_spec`, `resolve_account_specs` | Merge overrides and expand `${ENV_VAR}` placeholders; opt-in `allow_whole_dollar_env` for bare `$NAME`     |
-| `substitute_env_placeholders`                   | Replace `${NAME}` substrings from the environment; opt-in `allow_whole_dollar_env` for whole-value `$NAME` |
+| Symbol                                          | Role                                                                                                                                                                                                                                                                              |
+| ----------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| `MT5Client`                                     | Read-only data client with optional `order_check` / `order_send`                                                                                                                                                                                                                  |
+| `build_config`                                  | Build `pdmt5.Mt5Config` from connection fields; `login` accepts `int \| str \| None` — numeric strings are coerced to `int`, blank strings are treated as unset, and `${ENV_VAR}` / `$ENV_NAME` placeholders in string parameters are expanded when `allow_whole_dollar_env=True` |
+| `mt5_session`                                   | Context manager: initialize, login, yield client, shutdown                                                                                                                                                                                                                        |
+| `create_trading_client`, `mt5_trading_session`  | Trading-capable `pdmt5.Mt5TradingClient` lifecycle                                                                                                                                                                                                                                |
+| `AccountSpec`                                   | Generic account group: symbols plus optional credentials                                                                                                                                                                                                                          |
+| `resolve_account_spec`, `resolve_account_specs` | Merge overrides and expand `${ENV_VAR}` placeholders; opt-in `allow_whole_dollar_env` for bare `$NAME`                                                                                                                                                                            |
+| `substitute_env_placeholders`                   | Replace `${NAME}` substrings from the environment; opt-in `allow_whole_dollar_env` for whole-value `$NAME`                                                                                                                                                                        |
+| `substitute_mapping_values`                     | Recursively traverse a dict/list/scalar structure and substitute `${ENV_VAR}` placeholders for caller-selected mapping keys only; optionally normalise blank strings to `None` for a separate caller-selected key set; does not hard-code any application-specific key names      |
 
 Credential resolution is generic: any environment variable name may appear inside
 `${...}`. mt5cli does not hard-code application-specific keys such as
 `mt5_login` or `mt5_exe`.
 
 Pass `allow_whole_dollar_env=True` to `substitute_env_placeholders()`,
-`resolve_account_spec()`, `resolve_account_specs()`, and `build_config()` to
-additionally expand strings whose entire value is a bare `$ENV_NAME` identifier.
+`substitute_mapping_values()`, `resolve_account_spec()`, `resolve_account_specs()`,
+and `build_config()` to additionally expand strings whose entire value is a bare
+`$ENV_NAME` identifier.
 Partial strings such as `"plan$pass"`, `"abc$ENV"`, or `"$ENV-suffix"` are
 **never** expanded — only an exact `$IDENTIFIER` whole-string match qualifies.
 Default is `False` to preserve backward compatibility.
 
-### Read-only MT5 data access
-
-Module-level helpers open a transient connection per call. Prefer `mt5_session`
-or `MT5Client` when making many requests in one process.
-
-| Area                 | Symbols                                                                                              |
-| -------------------- | ---------------------------------------------------------------------------------------------------- |
-| Rates                | `copy_rates_from`, `copy_rates_from_pos`, `copy_rates_range`, `latest_rates`, `collect_latest_rates` |
-| Ticks                | `copy_ticks_from`, `copy_ticks_range`, `recent_ticks`                                                |
-| Account / terminal   | `account_info`, `terminal_info`, `mt5_version`, `last_error`, `mt5_summary`, `mt5_summary_as_df`     |
-| Symbols / market     | `symbols`, `symbol_info`, `symbol_info_tick`, `market_book`, `minimum_margins`                       |
-| Trading state (read) | `orders`, `positions`, `history_orders`, `history_deals`, `recent_history_deals`                     |
-
-Use `mt5_version` for MetaTrader 5 terminal version data. The name `version` at
-the package root refers to `importlib.metadata.version` (package metadata), not
-the MT5 SDK helper.
-
 ### Closed-bar rate helpers
 
 MetaTrader 5 returns the still-forming bar as the last row when
@@ -71,7 +65,6 @@ timestamp normalization in downstream apps.
 | `fetch_latest_closed_rates_indexed`              | Same as above but returns a UTC `DatetimeIndex` named `"time"` (no time column) |
 | `collect_latest_closed_rates_for_accounts`       | Multi-account closed bars with optional retry wrapper                           |
 | `collect_latest_closed_rates_by_granularity`     | Same data keyed by `(symbol, granularity_name)`                                 |
-| `collect_latest_rates_for_accounts`              | Latest bars including the forming bar when `start_pos=0`                        |
 | `collect_latest_rates_for_accounts_with_retries` | Bounded exponential backoff for transient MT5 errors                            |
 
 ### SQLite history collection and rate loading
@@ -99,18 +92,25 @@ diagrams.
 These helpers implement broker-facing calculations only. They do not encode
 strategy entries, exits, Kelly sizing, or signal logic.
 
-| Symbol                                                                                             | Role                                          |
-| -------------------------------------------------------------------------------------------------- | --------------------------------------------- |
-| `get_account_snapshot`, `get_symbol_snapshot`, `get_tick_snapshot`, `get_positions_frame`          | Normalized account/symbol/tick/position views |
-| `detect_position_side`                                                                             | Net long / short / flat from open positions   |
-| `calculate_spread_ratio`                                                                           | Relative bid-ask spread                       |
-| `calculate_margin_and_volume`, `calculate_volume_by_margin`, `calculate_new_position_margin_ratio` | Margin budget and volume sizing               |
-| `normalize_order_volume`, `estimate_order_margin`, `calculate_positions_margin`                    | Broker volume normalization and margin totals |
-| `determine_order_limits`                                                                           | SL/TP price levels from ratios                |
-| `ensure_symbol_selected`                                                                           | Select/verify Market Watch visibility         |
-| `place_market_order`, `close_open_positions`, `update_sltp_for_open_positions`                     | Order execution helpers (`dry_run` supported) |
-| `MarginVolume`, `OrderLimits`, `OrderExecutionResult`                                              | Typed return contracts for order helpers      |
-| `OrderSide`, `OrderFillingMode`, `OrderTimeMode`, `PositionSide`, `ExecutionStatus`                | Typed enums for order helpers                 |
+| Symbol                                                                                                                         | Role                                                              |
+| ------------------------------------------------------------------------------------------------------------------------------ | ----------------------------------------------------------------- |
+| `get_account_snapshot`, `get_symbol_snapshot`, `get_tick_snapshot`, `get_positions_frame`                                      | Normalized account/symbol/tick/position views                     |
+| `extract_tick_price`                                                                                                           | Positive finite bid/ask extraction from tick mappings             |
+| `detect_position_side`                                                                                                         | Net long / short / flat from open positions                       |
+| `calculate_spread_ratio`                                                                                                       | Relative bid-ask spread                                           |
+| `calculate_margin_and_volume`, `calculate_volume_by_margin`, `calculate_new_position_margin_ratio`                             | Margin budget and volume sizing                                   |
+| `normalize_order_volume`, `estimate_order_margin`, `calculate_positions_margin`                                                | Broker volume normalization and margin totals                     |
+| `calculate_positions_margin_by_symbol`                                                                                         | Per-symbol margin map (resilient, first-seen order)               |
+| `calculate_positions_margin_safe`                                                                                              | Summed total margin across symbols (failed symbols skipped)       |
+| `calculate_projected_margin_ratio`                                                                                             | Estimated symbol-scoped margin/equity after optional new exposure |
+| `calculate_account_projected_margin_ratio`                                                                                     | Account snapshot margin/equity after optional new exposure        |
+| `calculate_symbol_group_margin_ratio`                                                                                          | Estimated symbol-group margin/equity with optional exposure       |
+| `determine_order_limits`                                                                                                       | SL/TP price levels from ratios                                    |
+| `calculate_trailing_stop_updates`                                                                                              | Per-ticket generic trailing stop-loss update plan                 |
+| `ensure_symbol_selected`                                                                                                       | Select/verify Market Watch visibility                             |
+| `place_market_order`, `close_open_positions`, `update_sltp_for_open_positions`, `update_trailing_stop_loss_for_open_positions` | Order execution helpers (`dry_run` supported)                     |
+| `MarginVolume`, `OrderLimits`, `OrderExecutionResult`                                                                          | Typed return contracts for order helpers                          |
+| `OrderSide`, `OrderFillingMode`, `OrderTimeMode`, `PositionSide`, `ExecutionStatus`                                            | Typed enums for order helpers                                     |
 
 `MT5Client.order_send()` and CLI `order-send --yes` are live execution paths.
 
@@ -133,13 +133,43 @@ and returned as `status="failed"` with normalized `request` / `response` details
 | `normalize_mt5_exception`, `call_with_normalized_errors`, `is_recoverable_mt5_error` | Error normalization and retry classification    |
 | `Mt5Config`, `Mt5RuntimeError`, `Mt5TradingClient`, `Mt5TradingError`                | Re-exported pdmt5 types for adapter convenience |
 
-### Additional public exports (secondary)
+## Secondary public exports
 
-The package root also exports schema, storage, and parsing helpers (for example
-`DataKind`, `Dataset`, `normalize_dataframe`, `export_dataframe`,
-`parse_timeframe`, `TIMEFRAME_MAP`). These are public but oriented toward export
-pipelines and advanced integration. Prefer the stable symbols above for core
-infrastructure.
+These names remain importable from `mt5cli` and are covered by
+`SECONDARY_PUBLIC_EXPORTS`, but they are oriented toward CLI/export/schema
+integrations, parsing, and lower-level MT5 access rather than the stable core
+SDK surface. Prefer the stable symbols above for downstream infrastructure
+adapters.
+
+### Read-only MT5 data wrappers
+
+Module-level helpers open a transient connection per call. Prefer `mt5_session`
+or `MT5Client` when making many requests in one process.
+
+| Area                 | Symbols                                                                                              |
+| -------------------- | ---------------------------------------------------------------------------------------------------- |
+| Rates                | `copy_rates_from`, `copy_rates_from_pos`, `copy_rates_range`, `latest_rates`, `collect_latest_rates` |
+| Ticks                | `copy_ticks_from`, `copy_ticks_range`, `recent_ticks`                                                |
+| Account / terminal   | `account_info`, `terminal_info`, `mt5_version`, `last_error`, `mt5_summary`, `mt5_summary_as_df`     |
+| Symbols / market     | `symbols`, `symbol_info`, `symbol_info_tick`, `market_book`, `minimum_margins`                       |
+| Trading state (read) | `orders`, `positions`, `history_orders`, `history_deals`, `recent_history_deals`                     |
+| Multi-account rates  | `collect_latest_rates_for_accounts`                                                                  |
+
+Use `mt5_version` for MetaTrader 5 terminal version data. The name `version` at
+the package root refers to `importlib.metadata.version` (package metadata), not
+the MT5 SDK helper.
+
+### Schema, export, and parser helpers
+
+| Area                 | Symbols                                                                                                       |
+| -------------------- | ------------------------------------------------------------------------------------------------------------- |
+| Dataset contracts    | `DataKind`, `Dataset`, `IfExists`, `DEDUP_KEYS`, `REQUIRED_COLUMNS`, `TIME_COLUMNS`, `KNOWN_MT5_TIME_COLUMNS` |
+| Schema normalization | `normalize_dataframe`, `normalize_time_columns`, `schema_columns`, `validate_schema`                          |
+| Export helpers       | `detect_format`, `export_dataframe`, `export_dataframe_to_sqlite`                                             |
+| Symbol parsing       | `normalize_symbol`, `normalize_symbols`                                                                       |
+| Time parsing         | `ensure_utc`, `parse_date_range`, `parse_datetime`, `recent_window`                                           |
+| MT5 parsing maps     | `granularity_name`, `parse_tick_flags`, `parse_timeframe`, `TICK_FLAG_MAP`, `TIMEFRAME_MAP`                   |
+| Trading data shapes  | `POSITION_COLUMNS`                                                                                            |
 
 ## CLI commands
 
@@ -188,7 +218,7 @@ their own adapter layer.
 
 ## Contract verification
 
-`tests/test_contracts.py` asserts that every name in `STABLE_SDK_EXPORTS` is
-importable from `mt5cli`, documents key closed-bar, rate-view, SQLite loading,
-account-resolution, and trading-session behaviors, and keeps the contract set
-aligned with `__all__`.
+`tests/test_contracts.py` asserts that every name in the stable and secondary
+tier sets is importable from `mt5cli`, documents key closed-bar, rate-view,
+SQLite loading, account-resolution, and trading-session behaviors, and keeps the
+tier sets aligned with `__all__`.

docs/api/sdk.md

@@ -31,7 +31,7 @@ rates = collect_latest_rates_for_accounts_with_retries(
 ### Latest closed rate bars
 
 MetaTrader 5 `start_pos=0` includes the still-forming current bar as the last
-row. `fetch_latest_closed_rates()` handles one connected `Mt5CliClient`; use
+row. `fetch_latest_closed_rates()` handles one connected `MT5Client`; use
 `fetch_latest_closed_rates_for_trading_client()` from an active
 `Mt5TradingClient` session. Multi-account helpers fetch `count + 1` bars, drop
 that row with `drop_forming_rate_bar()`, and validate each series is non-empty. Returned frames are ordered
@@ -170,5 +170,5 @@ resulting `ValueError` is suppressed along with other recoverable errors.
 ## Trading-capable sessions
 
 For order placement and trading calculations, use the dedicated
-[Trading module](trading.md). The read-only `Mt5CliClient` and `mt5_session()`
-helpers in this module are unchanged.
+[Trading module](trading.md). Use `mt5_session()` / `MT5Client` for read-only
+collection.

docs/api/trading.md

@@ -31,7 +31,7 @@ finally:
 `login` accepts `int`, numeric `str`, or an empty string; empty strings are
 treated as unset. `path`, `password`, `server`, and `timeout` are forwarded to
 `pdmt5.Mt5Config`, and omitted `timeout` values keep the lower-level default.
-The read-only `Mt5CliClient` / `mt5_session()` API is unchanged.
+Use `mt5_session()` / `MT5Client` for read-only data collection.
 
 ## State and order helpers
 
@@ -194,6 +194,6 @@ through the stable package root without embedding entry/exit policy.
 | Local SL/TP price derivation                             | `determine_order_limits()`                                                              |
 | Throttled SQLite history loop with ad-hoc error handling | `ThrottledHistoryUpdater(suppress_errors=True)`                                         |
 
-Keep read-only data collection on `mt5_session()` / `Mt5CliClient`; use
+Keep read-only data collection on `mt5_session()` / `MT5Client`; use
 `mt5_trading_session()` only where order placement or trading calculations are
 required.

docs/index.md

@@ -29,7 +29,7 @@ pip install mt5cli
 
 ## Python API for downstream packages
 
-Import `MT5Client` for generic MT5 data access, schema normalization, and optional order primitives. `Mt5CliClient` remains available as a backward-compatible alias.
+Import `MT5Client` for generic MT5 data access, schema normalization, and optional order primitives.
 
 ```python
 from datetime import UTC, datetime

mt5cli/__init__.py

@@ -11,7 +11,11 @@ from importlib.metadata import version
 from pdmt5 import Mt5Config, Mt5RuntimeError, Mt5TradingClient, Mt5TradingError
 
 from .client import MT5Client, build_config, mt5_session
-from .contract import STABLE_SDK_EXPORTS
+from .contract import (
+    PUBLIC_EXPORT_TIERS,
+    SECONDARY_PUBLIC_EXPORTS,
+    STABLE_SDK_EXPORTS,
+)
 from .converters import (
     ensure_utc,
     granularity_name,
@@ -59,7 +63,6 @@ from .schemas import (
 )
 from .sdk import (
     AccountSpec,
-    Mt5CliClient,
     ThrottledHistoryUpdater,
     account_info,
     collect_history,
@@ -89,6 +92,7 @@ from .sdk import (
     resolve_account_spec,
     resolve_account_specs,
     substitute_env_placeholders,
+    substitute_mapping_values,
     symbol_info,
     symbol_info_tick,
     symbols,
@@ -116,10 +120,16 @@ from .trading import (
     OrderSide,
     OrderTimeMode,
     PositionSide,
+    calculate_account_projected_margin_ratio,
     calculate_margin_and_volume,
     calculate_new_position_margin_ratio,
     calculate_positions_margin,
+    calculate_positions_margin_by_symbol,
+    calculate_positions_margin_safe,
+    calculate_projected_margin_ratio,
     calculate_spread_ratio,
+    calculate_symbol_group_margin_ratio,
+    calculate_trailing_stop_updates,
     calculate_volume_by_margin,
     close_open_positions,
     create_trading_client,
@@ -127,6 +137,7 @@ from .trading import (
     determine_order_limits,
     ensure_symbol_selected,
     estimate_order_margin,
+    extract_tick_price,
     fetch_latest_closed_rates_for_trading_client,
     fetch_latest_closed_rates_indexed,
     get_account_snapshot,
@@ -137,6 +148,7 @@ from .trading import (
     normalize_order_volume,
     place_market_order,
     update_sltp_for_open_positions,
+    update_trailing_stop_loss_for_open_positions,
 )
 from .utils import (
     TICK_FLAG_MAP,
@@ -152,7 +164,9 @@ __all__ = [
     "DEDUP_KEYS",
     "KNOWN_MT5_TIME_COLUMNS",
     "POSITION_COLUMNS",
+    "PUBLIC_EXPORT_TIERS",
     "REQUIRED_COLUMNS",
+    "SECONDARY_PUBLIC_EXPORTS",
     "STABLE_SDK_EXPORTS",
     "TICK_FLAG_MAP",
     "TIMEFRAME_MAP",
@@ -164,7 +178,6 @@ __all__ = [
     "IfExists",
     "MT5Client",
     "MarginVolume",
-    "Mt5CliClient",
     "Mt5CliError",
     "Mt5Config",
     "Mt5ConnectionError",
@@ -185,10 +198,16 @@ __all__ = [
     "build_config",
     "build_rate_targets",
     "build_rate_view_name",
+    "calculate_account_projected_margin_ratio",
     "calculate_margin_and_volume",
     "calculate_new_position_margin_ratio",
     "calculate_positions_margin",
+    "calculate_positions_margin_by_symbol",
+    "calculate_positions_margin_safe",
+    "calculate_projected_margin_ratio",
     "calculate_spread_ratio",
+    "calculate_symbol_group_margin_ratio",
+    "calculate_trailing_stop_updates",
     "calculate_volume_by_margin",
     "call_with_normalized_errors",
     "close_open_positions",
@@ -213,6 +232,7 @@ __all__ = [
     "estimate_order_margin",
     "export_dataframe",
     "export_dataframe_to_sqlite",
+    "extract_tick_price",
     "fetch_latest_closed_rates",
     "fetch_latest_closed_rates_for_trading_client",
     "fetch_latest_closed_rates_indexed",
@@ -264,6 +284,7 @@ __all__ = [
     "resolve_rate_view_names",
     "schema_columns",
     "substitute_env_placeholders",
+    "substitute_mapping_values",
     "symbol_info",
     "symbol_info_tick",
     "symbols",
@@ -271,5 +292,6 @@ __all__ = [
     "update_history",
     "update_history_with_config",
     "update_sltp_for_open_positions",
+    "update_trailing_stop_loss_for_open_positions",
     "validate_schema",
 ]

mt5cli/client.py

@@ -24,9 +24,7 @@ class MT5Client(Mt5CliClient):
     """Public client for generic MT5 data access and order primitives.
 
     Extends the read-only SDK client with optional order check/send helpers and
-    exposes the same connection lifecycle as :class:`~mt5cli.sdk.Mt5CliClient`.
-    Downstream applications such as private trading packages should prefer this
-    type over the legacy ``Mt5CliClient`` name.
+    exposes the same connection lifecycle as :func:`mt5_session`.
 
     mt5cli intentionally exposes minimal execution primitives only. Trading
     decisions, signals, strategies, backtests, and optimization remain the

mt5cli/contract.py

@@ -1,11 +1,10 @@
-"""Stable downstream SDK export names for mt5cli."""
+"""Downstream SDK export tiers for mt5cli."""
 
 from __future__ import annotations
 
 STABLE_SDK_EXPORTS: frozenset[str] = frozenset({
     "AccountSpec",
     "MT5Client",
-    "Mt5CliClient",
     "Mt5CliError",
     "Mt5Config",
     "Mt5ConnectionError",
@@ -24,36 +23,33 @@ STABLE_SDK_EXPORTS: frozenset[str] = frozenset({
     "OrderLimits",
     "RateTarget",
     "ThrottledHistoryUpdater",
-    "account_info",
     "build_config",
     "build_rate_targets",
     "build_rate_view_name",
+    "calculate_account_projected_margin_ratio",
     "calculate_margin_and_volume",
     "calculate_new_position_margin_ratio",
+    "calculate_projected_margin_ratio",
     "calculate_positions_margin",
+    "calculate_positions_margin_by_symbol",
+    "calculate_positions_margin_safe",
     "calculate_spread_ratio",
+    "calculate_symbol_group_margin_ratio",
+    "calculate_trailing_stop_updates",
     "calculate_volume_by_margin",
     "call_with_normalized_errors",
     "close_open_positions",
     "collect_history",
     "collect_latest_closed_rates_by_granularity",
     "collect_latest_closed_rates_for_accounts",
-    "collect_latest_rates",
-    "collect_latest_rates_for_accounts",
     "collect_latest_rates_for_accounts_with_retries",
-    "copy_rates_from",
-    "copy_rates_from_pos",
-    "copy_rates_range",
-    "copy_ticks_from",
-    "copy_ticks_range",
     "create_trading_client",
     "detect_position_side",
     "determine_order_limits",
     "drop_forming_rate_bar",
     "ensure_symbol_selected",
     "estimate_order_margin",
-    "export_dataframe",
-    "export_dataframe_to_sqlite",
+    "extract_tick_price",
     "fetch_latest_closed_rates",
     "fetch_latest_closed_rates_for_trading_client",
     "fetch_latest_closed_rates_indexed",
@@ -61,29 +57,16 @@ STABLE_SDK_EXPORTS: frozenset[str] = frozenset({
     "get_positions_frame",
     "get_symbol_snapshot",
     "get_tick_snapshot",
-    "history_deals",
-    "history_orders",
     "is_recoverable_mt5_error",
-    "last_error",
-    "latest_rates",
     "load_rate_data",
     "load_rate_data_from_connection",
     "load_rate_series_by_granularity",
     "load_rate_series_from_sqlite",
-    "market_book",
-    "minimum_margins",
     "mt5_session",
-    "mt5_summary",
-    "mt5_summary_as_df",
     "mt5_trading_session",
-    "mt5_version",
     "normalize_mt5_exception",
     "normalize_order_volume",
-    "orders",
     "place_market_order",
-    "positions",
-    "recent_history_deals",
-    "recent_ticks",
     "resolve_account_spec",
     "resolve_account_specs",
     "resolve_history_datasets",
@@ -94,13 +77,74 @@ STABLE_SDK_EXPORTS: frozenset[str] = frozenset({
     "resolve_rate_view_name",
     "resolve_rate_view_names",
     "substitute_env_placeholders",
+    "substitute_mapping_values",
+    "update_history",
+    "update_history_with_config",
+    "update_sltp_for_open_positions",
+    "update_trailing_stop_loss_for_open_positions",
+})
+
+SECONDARY_PUBLIC_EXPORTS: frozenset[str] = frozenset({
+    "DEDUP_KEYS",
+    "DataKind",
+    "Dataset",
+    "IfExists",
+    "KNOWN_MT5_TIME_COLUMNS",
+    "POSITION_COLUMNS",
+    "REQUIRED_COLUMNS",
+    "TICK_FLAG_MAP",
+    "TIMEFRAME_MAP",
+    "TIME_COLUMNS",
+    "account_info",
+    "collect_latest_rates",
+    "collect_latest_rates_for_accounts",
+    "copy_rates_from",
+    "copy_rates_from_pos",
+    "copy_rates_range",
+    "copy_ticks_from",
+    "copy_ticks_range",
+    "detect_format",
+    "ensure_utc",
+    "export_dataframe",
+    "export_dataframe_to_sqlite",
+    "granularity_name",
+    "history_deals",
+    "history_orders",
+    "last_error",
+    "latest_rates",
+    "market_book",
+    "minimum_margins",
+    "mt5_summary",
+    "mt5_summary_as_df",
+    "mt5_version",
+    "normalize_dataframe",
+    "normalize_symbol",
+    "normalize_symbols",
+    "normalize_time_columns",
+    "orders",
+    "parse_date_range",
+    "parse_datetime",
+    "parse_tick_flags",
+    "parse_timeframe",
+    "positions",
+    "recent_history_deals",
+    "recent_ticks",
+    "recent_window",
+    "schema_columns",
     "symbol_info",
     "symbol_info_tick",
     "symbols",
     "terminal_info",
-    "update_history",
-    "update_history_with_config",
-    "update_sltp_for_open_positions",
+    "validate_schema",
 })
 
-__all__ = ["STABLE_SDK_EXPORTS"]
+PUBLIC_EXPORT_TIERS: dict[str, frozenset[str]] = {
+    "stable": STABLE_SDK_EXPORTS,
+    "secondary": SECONDARY_PUBLIC_EXPORTS,
+}
+
+__all__ = [
+    "PUBLIC_EXPORT_TIERS",
+    "SECONDARY_PUBLIC_EXPORTS",
+    "STABLE_SDK_EXPORTS",
+]

mt5cli/sdk.py

@@ -40,7 +40,7 @@ from .utils import (
 from .utils import coerce_login as _coerce_login
 
 if TYPE_CHECKING:
-    from collections.abc import Callable, Iterator, Sequence
+    from collections.abc import Callable, Collection, Iterator, Sequence
 
     UpdateHistoryBackend = Callable[..., None]
 
@@ -142,6 +142,7 @@ __all__ = [
     "resolve_account_spec",
     "resolve_account_specs",
     "substitute_env_placeholders",
+    "substitute_mapping_values",
     "symbol_info",
     "symbol_info_tick",
     "symbols",
@@ -305,7 +306,7 @@ def _fetch_minimum_margins(client: Mt5DataClient, symbol: str) -> pd.DataFrame:
 def build_config(
     *,
     path: str | None = None,
-    login: int | None = None,
+    login: int | str | None = None,
     password: str | None = None,
     server: str | None = None,
     timeout: int | None = None,
@@ -315,14 +316,19 @@ def build_config(
 
     Args:
         path: Optional terminal executable path.
-        login: Optional trading account login.
+        login: Optional trading account login. Integers are preserved. String
+            values are coerced: empty or whitespace-only strings become
+            ``None``; numeric strings such as ``"12345"`` are converted to
+            ``int``; non-numeric strings raise ``ValueError``. When
+            ``allow_whole_dollar_env=True``, ``$ENV_NAME`` and
+            ``${ENV_NAME}`` placeholders are expanded before coercion.
         password: Optional trading account password.
         server: Optional trading server name.
         timeout: Optional connection timeout in milliseconds.
         allow_whole_dollar_env: When ``True``, string parameters that are
             exactly ``$ENV_NAME`` are expanded from the environment. Applies
-            to ``path``, ``password``, and ``server``. Default ``False``
-            preserves existing behavior.
+            to ``path``, ``login``, ``password``, and ``server``. Default
+            ``False`` preserves existing behavior.
 
     Returns:
         Configured ``Mt5Config`` instance.
@@ -330,6 +336,8 @@ def build_config(
     if allow_whole_dollar_env:
         if path is not None:
             path = substitute_env_placeholders(path, allow_whole_dollar_env=True)
+        if isinstance(login, str):
+            login = substitute_env_placeholders(login, allow_whole_dollar_env=True)
         if password is not None:
             password = substitute_env_placeholders(
                 password, allow_whole_dollar_env=True
@@ -338,7 +346,7 @@ def build_config(
             server = substitute_env_placeholders(server, allow_whole_dollar_env=True)
     return Mt5Config(
         path=path,
-        login=login,
+        login=_coerce_login(login),
         password=password,
         server=server,
         timeout=timeout,
@@ -1442,6 +1450,75 @@ def substitute_env_placeholders(
     return "".join(parts)
 
 
+def substitute_mapping_values(
+    data: object,
+    *,
+    keys: Collection[str],
+    allow_whole_dollar_env: bool = False,
+    blank_string_keys_as_none: Collection[str] = (),
+) -> object:
+    """Recursively substitute environment placeholders for selected mapping keys.
+
+    Traverses nested dicts and lists, expanding ``${ENV_VAR}`` (and
+    ``$ENV_NAME`` when ``allow_whole_dollar_env=True``) in string values
+    whose immediate parent dict key is in ``keys``.  Fields whose key is
+    not in ``keys`` are preserved exactly, including literal dollar signs.
+    Strings that are direct elements of a list are never substituted;
+    substitution only applies to strings that are immediate dict values.
+
+    This is a generic downstream config utility.  Key names such as
+    ``mt5_login`` or ``mt5_password`` must be supplied by the caller;
+    mt5cli does not hard-code any application-specific key names.
+    Callers are responsible for ensuring ``data`` has bounded nesting depth;
+    deeply nested or self-referential structures will hit Python's recursion
+    limit.
+
+    Args:
+        data: Arbitrarily nested dict/list/scalar value to process.
+        keys: Mapping keys whose string values receive placeholder
+            substitution.
+        allow_whole_dollar_env: When ``True``, a string that is exactly
+            ``$ENV_NAME`` (whole value) is also expanded from the
+            environment in addition to ``${ENV_NAME}`` placeholders.
+            Default ``False`` expands ``${ENV_NAME}`` only.
+        blank_string_keys_as_none: Mapping keys for which blank strings
+            (after any substitution) are normalised to ``None``.  A key
+            may appear in ``blank_string_keys_as_none`` without also
+            appearing in ``keys``.
+
+    Returns:
+        The processed value.  Dicts and lists are rebuilt into new
+        containers with selected string values substituted and
+        blank-normalised.  Scalar inputs (non-dict, non-list) are
+        returned as-is.
+    """
+    keys_set: frozenset[str] = frozenset(keys)
+    blank_keys_set: frozenset[str] = frozenset(blank_string_keys_as_none)
+
+    def _visit(node: object, current_key: str | None) -> object:
+        if isinstance(node, dict):
+            typed = cast("dict[object, object]", node)
+            return {
+                k: _visit(v, k if isinstance(k, str) else None)
+                for k, v in typed.items()
+            }
+        if isinstance(node, list):
+            typed_list = cast("list[object]", node)
+            return [_visit(item, None) for item in typed_list]
+        if not isinstance(node, str):
+            return node
+        text = node
+        if current_key in keys_set:
+            text = substitute_env_placeholders(
+                node, allow_whole_dollar_env=allow_whole_dollar_env
+            )
+        if current_key in blank_keys_set and not text.strip():
+            return None
+        return text
+
+    return _visit(data, None)
+
+
 def _resolve_field(
     override: str | None,
     account_value: str | None,

mt5cli/trading.py

@@ -2,21 +2,23 @@
 
 from __future__ import annotations
 
+import logging
 from contextlib import contextmanager
 from math import floor, isfinite
 from numbers import Integral, Real
 from typing import TYPE_CHECKING, Literal, TypedDict, cast
 
 import pandas as pd
-from pdmt5 import Mt5Config, Mt5TradingClient, Mt5TradingError
+from pdmt5 import Mt5Config, Mt5RuntimeError, Mt5TradingClient, Mt5TradingError
 
 from .history import drop_forming_rate_bar
 from .sdk import build_config
 from .utils import coerce_login as _coerce_login
-from .utils import parse_timeframe
 
 if TYPE_CHECKING:
-    from collections.abc import Iterator, Sequence
+    from collections.abc import Iterator, Mapping, Sequence
+
+_logger = logging.getLogger(__name__)
 
 PositionSide = Literal["long", "short"]
 OrderSide = Literal["BUY", "SELL"]
@@ -125,10 +127,16 @@ __all__ = [
     "OrderSide",
     "OrderTimeMode",
     "PositionSide",
+    "calculate_account_projected_margin_ratio",
     "calculate_margin_and_volume",
     "calculate_new_position_margin_ratio",
     "calculate_positions_margin",
+    "calculate_positions_margin_by_symbol",
+    "calculate_positions_margin_safe",
+    "calculate_projected_margin_ratio",
     "calculate_spread_ratio",
+    "calculate_symbol_group_margin_ratio",
+    "calculate_trailing_stop_updates",
     "calculate_volume_by_margin",
     "close_open_positions",
     "create_trading_client",
@@ -136,6 +144,7 @@ __all__ = [
     "determine_order_limits",
     "ensure_symbol_selected",
     "estimate_order_margin",
+    "extract_tick_price",
     "fetch_latest_closed_rates_for_trading_client",
     "fetch_latest_closed_rates_indexed",
     "get_account_snapshot",
@@ -146,6 +155,7 @@ __all__ = [
     "normalize_order_volume",
     "place_market_order",
     "update_sltp_for_open_positions",
+    "update_trailing_stop_loss_for_open_positions",
 ]
 
 
@@ -423,6 +433,30 @@ def _optional_price(value: object) -> float | None:
     return price
 
 
+def extract_tick_price(tick: Mapping[str, object], key: str) -> float | None:
+    """Return a positive finite float from tick[key], or None if invalid.
+
+    Accepts int, float, or numeric string values. Returns None when the key is
+    missing, the value is None, non-numeric, NaN, infinite, zero, or negative.
+    Booleans are treated as non-numeric and return None.
+    """
+    value = tick.get(key)
+    if value is None or isinstance(value, bool):
+        return None
+    if isinstance(value, int | float):
+        price = float(value)
+    elif isinstance(value, str):
+        try:
+            price = float(value)
+        except ValueError:
+            return None
+    else:
+        return None
+    if not isfinite(price) or price <= 0:
+        return None
+    return price
+
+
 def _success_retcodes(mt5: object) -> frozenset[int]:
     values = {
         value
@@ -461,9 +495,10 @@ def _calculate_min_volume_if_affordable(
         msg = f"Invalid volume constraints for {symbol!r}."
         raise Mt5TradingError(msg)
     side = _normalize_order_side(order_side)
-    tick = get_tick_snapshot(client, symbol)
-    price = tick["ask"] if side == "BUY" else tick["bid"]
-    if not isinstance(price, int | float) or price <= 0:
+    price = extract_tick_price(
+        get_tick_snapshot(client, symbol), "ask" if side == "BUY" else "bid"
+    )
+    if price is None:
         msg = f"Tick price is unavailable for {symbol!r}."
         raise Mt5TradingError(msg)
     order_type = (
@@ -621,14 +656,14 @@ def estimate_order_margin(
         raise Mt5TradingError(msg)
     side = _normalize_order_side(order_side)
     tick = get_tick_snapshot(client, symbol)
-    price = tick["ask"] if side == "BUY" else tick["bid"]
-    if not isinstance(price, int | float) or price <= 0 or not isfinite(price):
+    price = extract_tick_price(tick, "ask" if side == "BUY" else "bid")
+    if price is None:
         msg = f"Tick price is unavailable for {symbol!r}."
         raise Mt5TradingError(msg)
     order_type = (
         client.mt5.ORDER_TYPE_BUY if side == "BUY" else client.mt5.ORDER_TYPE_SELL
     )
-    raw_margin = client.order_calc_margin(order_type, symbol, volume, float(price))
+    raw_margin = client.order_calc_margin(order_type, symbol, volume, price)
     try:
         margin = float(raw_margin)
     except (TypeError, ValueError) as exc:
@@ -682,22 +717,85 @@ def calculate_positions_margin(
     return total
 
 
+def calculate_positions_margin_by_symbol(
+    client: Mt5TradingClient,
+    *,
+    symbols: Sequence[str],
+    suppress_errors: bool = True,
+) -> dict[str, float]:
+    """Return per-symbol estimated margin for open positions.
+
+    Computes margin for each unique input symbol independently using the strict
+    :func:`calculate_positions_margin` helper. Duplicates are deduplicated in
+    first-seen order.
+
+    Args:
+        client: Connected ``Mt5TradingClient`` instance.
+        symbols: Symbols to compute margin for.
+        suppress_errors: When ``True``, log and skip symbols that raise
+            ``Mt5TradingError``, ``Mt5RuntimeError``, or ``AttributeError``.
+            When ``False``, re-raise the first failure.
+
+    Returns:
+        Mapping of symbol to margin total in first-seen unique-symbol order.
+        Returns an empty dict when ``symbols`` is empty or all symbols fail
+        with ``suppress_errors=True``.
+
+    Raises:
+        Mt5TradingError: When a symbol raises ``Mt5TradingError`` and
+            ``suppress_errors=False``.
+        Mt5RuntimeError: When a symbol raises ``Mt5RuntimeError`` and
+            ``suppress_errors=False``.
+        AttributeError: When a symbol raises ``AttributeError`` and
+            ``suppress_errors=False``.
+    """
+    result: dict[str, float] = {}
+    for symbol in dict.fromkeys(symbols):
+        try:
+            result[symbol] = calculate_positions_margin(client, symbols=[symbol])
+        except (Mt5TradingError, Mt5RuntimeError, AttributeError) as exc:
+            if not suppress_errors:
+                raise
+            _logger.warning("Skipping margin for %r: %s", symbol, exc)
+    return result
+
+
+def calculate_positions_margin_safe(
+    client: Mt5TradingClient,
+    *,
+    symbols: Sequence[str],
+) -> float:
+    """Return the total estimated margin for open positions across symbols.
+
+    Internally calls :func:`calculate_positions_margin_by_symbol` with
+    ``suppress_errors=True``. Failed symbols are silently skipped.
+
+    Args:
+        client: Connected ``Mt5TradingClient`` instance.
+        symbols: Symbols to include.
+
+    Returns:
+        Sum of per-symbol margins; ``0.0`` when no symbols or all fail.
+    """
+    return sum(
+        calculate_positions_margin_by_symbol(client, symbols=symbols).values(),
+        0.0,
+    )
+
+
 def calculate_spread_ratio(client: Mt5TradingClient, symbol: str) -> float:
     """Return ``(ask - bid) / ((ask + bid) / 2)`` for the latest tick.
 
     Raises:
-        Mt5TradingError: If bid or ask is unavailable or non-positive.
+        Mt5TradingError: If bid or ask is unavailable.
     """
     tick = get_tick_snapshot(client, symbol)
-    bid = tick.get("bid")
-    ask = tick.get("ask")
-    if not isinstance(bid, int | float) or not isinstance(ask, int | float):
+    bid = extract_tick_price(tick, "bid")
+    ask = extract_tick_price(tick, "ask")
+    if bid is None or ask is None:
         msg = f"Tick bid/ask is unavailable for {symbol!r}."
         raise Mt5TradingError(msg)
-    if bid <= 0 or ask <= 0:
-        msg = f"Tick bid/ask must be positive for {symbol!r}."
-        raise Mt5TradingError(msg)
-    return (float(ask) - float(bid)) / ((float(ask) + float(bid)) / 2.0)
+    return (ask - bid) / ((ask + bid) / 2.0)
 
 
 def calculate_new_position_margin_ratio(
@@ -720,9 +818,10 @@ def calculate_new_position_margin_ratio(
     margin = float(account.get("margin") or 0.0)
     if new_position_side is not None and new_position_volume > 0:
         side = _normalize_order_side(new_position_side)
-        tick = get_tick_snapshot(client, symbol)
-        price = tick["ask"] if side == "BUY" else tick["bid"]
-        if not isinstance(price, int | float) or price <= 0:
+        price = extract_tick_price(
+            get_tick_snapshot(client, symbol), "ask" if side == "BUY" else "bid"
+        )
+        if price is None:
             msg = f"Tick price is unavailable for {symbol!r}."
             raise Mt5TradingError(msg)
         order_type = (
@@ -734,6 +833,147 @@ def calculate_new_position_margin_ratio(
     return margin / equity
 
 
+def _account_equity(client: Mt5TradingClient) -> float:
+    account = get_account_snapshot(client)
+    return _required_account_number(account, "equity", allow_zero=False)
+
+
+def _required_account_number(
+    account: Mapping[str, object],
+    field: str,
+    *,
+    allow_zero: bool,
+) -> float:
+    raw_value = account.get(field)
+    if isinstance(raw_value, bool) or not isinstance(raw_value, Real):
+        msg = f"Account {field} must be a finite number to calculate margin ratio."
+        raise Mt5TradingError(msg)
+    value = float(raw_value)
+    if (
+        not isfinite(value)
+        or (not allow_zero and value <= 0)
+        or (allow_zero and value < 0)
+    ):
+        msg = (
+            f"Account {field} must be a non-negative finite number."
+            if allow_zero
+            else f"Account {field} must be a positive finite number."
+        )
+        raise Mt5TradingError(msg)
+    return value
+
+
+def calculate_account_projected_margin_ratio(
+    client: Mt5TradingClient,
+    *,
+    symbol: str | None = None,
+    new_position_side: OrderSide | None = None,
+    new_position_volume: float = 0.0,
+) -> float:
+    """Return account-wide current plus optional new-position margin over equity.
+
+    Current exposure comes from the broker account snapshot ``margin`` field so
+    unrelated open positions remain in the baseline. Optional projected
+    exposure is added via :func:`estimate_order_margin` only when a symbol, side,
+    and positive volume are all supplied.
+
+    """
+    account = get_account_snapshot(client)
+    equity = _required_account_number(account, "equity", allow_zero=False)
+    margin = _required_account_number(account, "margin", allow_zero=True)
+    if symbol is not None and new_position_side is not None and new_position_volume > 0:
+        margin += estimate_order_margin(
+            client,
+            symbol,
+            new_position_side,
+            new_position_volume,
+        )
+    return margin / equity
+
+
+def calculate_projected_margin_ratio(
+    client: Mt5TradingClient,
+    *,
+    symbol: str,
+    new_position_side: OrderSide | None = None,
+    new_position_volume: float = 0.0,
+) -> float:
+    """Return estimated current plus optional new-position margin over equity.
+
+    Current exposure is estimated from open positions with
+    :func:`calculate_positions_margin`. Optional projected exposure is added via
+    :func:`estimate_order_margin`. Thresholds and guard actions are intentionally
+    left to downstream applications.
+
+    Account equity, position margin, and optional projected margin errors from
+    the composed MT5 helpers propagate to the caller.
+    """
+    equity = _account_equity(client)
+    margin = calculate_positions_margin(client, symbols=[symbol])
+    if new_position_side is not None and new_position_volume > 0:
+        margin += estimate_order_margin(
+            client,
+            symbol,
+            new_position_side,
+            new_position_volume,
+        )
+    return margin / equity
+
+
+def calculate_symbol_group_margin_ratio(
+    client: Mt5TradingClient,
+    *,
+    symbols: Sequence[str],
+    new_symbol: str | None = None,
+    new_position_side: OrderSide | None = None,
+    new_position_volume: float = 0.0,
+    suppress_errors: bool = True,
+) -> float:
+    """Return estimated symbol-group margin over account equity.
+
+    Per-symbol current exposure is summed with
+    :func:`calculate_positions_margin_by_symbol`. When ``new_symbol`` is inside
+    the input symbol group, optional projected order margin is added for that
+    symbol. Invalid equity always raises to fail closed.
+
+    Raises:
+        AttributeError: When symbol margin lookup or projected margin lookup
+            fails and ``suppress_errors`` is ``False``.
+        Mt5RuntimeError: When symbol margin lookup or projected margin lookup
+            fails and ``suppress_errors`` is ``False``.
+        Mt5TradingError: When account equity is invalid, or when symbol margin
+            lookup or projected margin lookup fails and ``suppress_errors`` is
+            ``False``.
+    """
+    equity = _account_equity(client)
+    unique_symbols = list(dict.fromkeys(symbols))
+    margin = sum(
+        calculate_positions_margin_by_symbol(
+            client,
+            symbols=unique_symbols,
+            suppress_errors=suppress_errors,
+        ).values(),
+        0.0,
+    )
+    if (
+        new_symbol in unique_symbols
+        and new_position_side is not None
+        and new_position_volume > 0
+    ):
+        try:
+            margin += estimate_order_margin(
+                client,
+                new_symbol,
+                new_position_side,
+                new_position_volume,
+            )
+        except (Mt5TradingError, Mt5RuntimeError, AttributeError):
+            if not suppress_errors:
+                raise
+            _logger.warning("Skipping projected margin for %r.", new_symbol)
+    return margin / equity
+
+
 def calculate_margin_and_volume(
     client: Mt5TradingClient,
     symbol: str,
@@ -780,28 +1020,8 @@ def calculate_margin_and_volume(
             "SELL",
         )
     else:
-        native_calculate_volume = getattr(client, "calculate_volume_by_margin", None)
-        if callable(native_calculate_volume):
-            buy_volume = float(
-                cast(
-                    "float | int | str",
-                    native_calculate_volume(symbol, trade_margin, "BUY"),
-                ),
-            )
-            sell_volume = float(
-                cast(
-                    "float | int | str",
-                    native_calculate_volume(symbol, trade_margin, "SELL"),
-                ),
-            )
-        else:
-            buy_volume = calculate_volume_by_margin(client, symbol, trade_margin, "BUY")
-            sell_volume = calculate_volume_by_margin(
-                client,
-                symbol,
-                trade_margin,
-                "SELL",
-            )
+        buy_volume = calculate_volume_by_margin(client, symbol, trade_margin, "BUY")
+        sell_volume = calculate_volume_by_margin(client, symbol, trade_margin, "SELL")
     try:
         symbol_info = get_symbol_snapshot(client, symbol)
         volume_min = float(symbol_info.get("volume_min") or 0.0)
@@ -847,8 +1067,10 @@ def calculate_volume_by_margin(
         msg = f"Invalid volume constraints for {symbol!r}."
         raise Mt5TradingError(msg)
     side = _normalize_order_side(order_side)
-    price = get_tick_snapshot(client, symbol)["ask" if side == "BUY" else "bid"]
-    if not isinstance(price, int | float) or price <= 0:
+    price = extract_tick_price(
+        get_tick_snapshot(client, symbol), "ask" if side == "BUY" else "bid"
+    )
+    if price is None:
         msg = f"Tick price is unavailable for {symbol!r}."
         raise Mt5TradingError(msg)
     order_type = (
@@ -924,11 +1146,11 @@ def determine_order_limits(
     _require_protective_ratio(take_profit_ratio, "take_profit_limit_ratio")
     normalized_side = _position_side_from_order_side(side)
     tick = get_tick_snapshot(client, symbol)
-    entry_value = tick["ask"] if normalized_side == "long" else tick["bid"]
-    if not isinstance(entry_value, int | float):
+    entry_key = "ask" if normalized_side == "long" else "bid"
+    entry = extract_tick_price(tick, entry_key)
+    if entry is None:
         msg = f"Tick price is unavailable for {symbol!r}."
         raise Mt5TradingError(msg)
-    entry = float(entry_value)
     try:
         symbol_info = get_symbol_snapshot(client, symbol)
     except (AttributeError, KeyError, TypeError, ValueError):
@@ -1004,8 +1226,8 @@ def place_market_order(
     if not dry_run:
         ensure_symbol_selected(client, symbol)
     tick = get_tick_snapshot(client, symbol)
-    price = tick["ask"] if side == "BUY" else tick["bid"]
-    if not isinstance(price, int | float) or price <= 0:
+    price = extract_tick_price(tick, "ask" if side == "BUY" else "bid")
+    if price is None:
         msg = f"Tick price is unavailable for {symbol!r}."
         raise Mt5TradingError(msg)
     request = {
@@ -1015,7 +1237,7 @@ def place_market_order(
         "type": (
             client.mt5.ORDER_TYPE_BUY if side == "BUY" else client.mt5.ORDER_TYPE_SELL
         ),
-        "price": float(price),
+        "price": price,
         "type_filling": _resolve_mt5_constant(
             client.mt5,
             "ORDER_FILLING",
@@ -1112,6 +1334,125 @@ def close_open_positions(
     return results
 
 
+def _symbol_digits(client: Mt5TradingClient, symbol: str) -> int | None:
+    try:
+        raw_digits = get_symbol_snapshot(client, symbol).get("digits")
+        if raw_digits is None:
+            return None
+        digits = int(raw_digits)
+    except (AttributeError, TypeError, ValueError):
+        return None
+    return digits if digits >= 0 else None
+
+
+def _position_ticket(value: object) -> int | None:
+    ticket = _optional_int(value)
+    return ticket if ticket is not None and ticket > 0 else None
+
+
+def _current_stop_loss(value: object) -> float | None:
+    return _optional_price(value)
+
+
+def _trailing_stop_loss(
+    client: Mt5TradingClient,
+    *,
+    position_type: object,
+    current_sl: float | None,
+    bid: float | None,
+    ask: float | None,
+    digits: int,
+    trailing_stop_ratio: float,
+) -> float | None:
+    next_sl: float | None = None
+    if position_type == client.mt5.POSITION_TYPE_BUY:
+        if bid is not None:
+            next_sl = round(bid * (1.0 - trailing_stop_ratio), digits)
+            if current_sl is not None and current_sl >= next_sl:
+                next_sl = None
+    elif position_type == client.mt5.POSITION_TYPE_SELL and ask is not None:
+        next_sl = round(ask * (1.0 + trailing_stop_ratio), digits)
+        if current_sl is not None and current_sl <= next_sl:
+            next_sl = None
+    return next_sl
+
+
+def calculate_trailing_stop_updates(
+    client: Mt5TradingClient,
+    *,
+    symbol: str,
+    trailing_stop_ratio: float,
+) -> dict[int, float]:
+    """Return per-ticket trailing stop-loss updates for open symbol positions.
+
+    Buy positions trail from bid using ``bid * (1 - trailing_stop_ratio)``.
+    Sell positions trail from ask using ``ask * (1 + trailing_stop_ratio)``.
+    Existing stop losses are preserved when they are already more favorable.
+    Missing symbol metadata returns an empty update map. Positions with a
+    missing side-specific tick price are skipped.
+    """
+    _require_protective_ratio(trailing_stop_ratio, "trailing_stop_ratio")
+    positions = get_positions_frame(client, symbol=symbol)
+    if positions.empty:
+        return {}
+    tick = get_tick_snapshot(client, symbol)
+    bid = extract_tick_price(tick, "bid")
+    ask = extract_tick_price(tick, "ask")
+    digits = _symbol_digits(client, symbol)
+    if digits is None:
+        return {}
+
+    updates: dict[int, float] = {}
+    for row in positions.to_dict("records"):
+        ticket = _position_ticket(row.get("ticket"))
+        if ticket is None:
+            continue
+        next_sl = _trailing_stop_loss(
+            client,
+            position_type=row.get("type"),
+            current_sl=_current_stop_loss(row.get("sl")),
+            bid=bid,
+            ask=ask,
+            digits=digits,
+            trailing_stop_ratio=trailing_stop_ratio,
+        )
+        if next_sl is None:
+            continue
+        updates[ticket] = next_sl
+    return updates
+
+
+def update_trailing_stop_loss_for_open_positions(
+    client: Mt5TradingClient,
+    *,
+    symbol: str,
+    trailing_stop_ratio: float,
+    dry_run: bool = False,
+) -> list[OrderExecutionResult]:
+    """Update open positions whose trailing stop loss should move favorably.
+
+    Returns:
+        Normalized execution results for positions that need an SL update.
+    """
+    updates = calculate_trailing_stop_updates(
+        client,
+        symbol=symbol,
+        trailing_stop_ratio=trailing_stop_ratio,
+    )
+    results: list[OrderExecutionResult] = []
+    for ticket, stop_loss in updates.items():
+        results.extend(
+            update_sltp_for_open_positions(
+                client,
+                symbol=symbol,
+                tickets=[ticket],
+                stop_loss=stop_loss,
+                dry_run=dry_run,
+            ),
+        )
+    return results
+
+
 def update_sltp_for_open_positions(
     client: Mt5TradingClient,
     *,
@@ -1197,19 +1538,10 @@ def fetch_latest_closed_rates_for_trading_client(
         msg = "count must be positive."
         raise ValueError(msg)
     fetch_method = getattr(client, "fetch_latest_rates_as_df", None)
-    if callable(fetch_method):
-        fetched = fetch_method(symbol, granularity, count + 1)
-    else:
-        copy_method = getattr(client, "copy_rates_from_pos_as_df", None)
-        if not callable(copy_method):
-            msg = "MT5 trading client cannot fetch rate data."
-            raise Mt5TradingError(msg)
-        fetched = copy_method(
-            symbol=symbol,
-            timeframe=parse_timeframe(granularity),
-            start_pos=0,
-            count=count + 1,
-        )
+    if not callable(fetch_method):
+        msg = "MT5 trading client cannot fetch rate data."
+        raise Mt5TradingError(msg)
+    fetched = fetch_method(symbol, granularity, count + 1)
     if not isinstance(fetched, pd.DataFrame):
         msg = (
             f"Malformed rate data for {symbol!r} at granularity {granularity!r}: "

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "mt5cli"
-version = "0.9.1"
+version = "0.9.5"
 description = "Generic MT5 data and execution infrastructure for Python applications"
 authors = [{name = "dceoy", email = "dceoy@users.noreply.github.com"}]
 maintainers = [{name = "dceoy", email = "dceoy@users.noreply.github.com"}]

tests/test_contracts.py

@@ -2,9 +2,11 @@
 
 from __future__ import annotations
 
+import re
 import sqlite3
 from datetime import UTC, datetime
-from typing import TYPE_CHECKING, get_type_hints
+from pathlib import Path
+from typing import get_type_hints
 from unittest.mock import MagicMock
 
 import pandas as pd
@@ -15,7 +17,9 @@ from pytest_mock import MockerFixture  # noqa: TC002
 import mt5cli
 from mt5cli import (
     DEDUP_KEYS,
+    PUBLIC_EXPORT_TIERS,
     REQUIRED_COLUMNS,
+    SECONDARY_PUBLIC_EXPORTS,
     STABLE_SDK_EXPORTS,
     TIME_COLUMNS,
     AccountSpec,
@@ -33,8 +37,12 @@ from mt5cli import (
     RateTarget,
     build_config,
     build_rate_targets,
+    calculate_account_projected_margin_ratio,
     calculate_margin_and_volume,
     calculate_positions_margin,
+    calculate_projected_margin_ratio,
+    calculate_symbol_group_margin_ratio,
+    calculate_trailing_stop_updates,
     call_with_normalized_errors,
     detect_format,
     drop_forming_rate_bar,
@@ -42,6 +50,7 @@ from mt5cli import (
     ensure_utc,
     export_dataframe,
     export_dataframe_to_sqlite,
+    extract_tick_price,
     fetch_latest_closed_rates,
     fetch_latest_closed_rates_for_trading_client,
     fetch_latest_closed_rates_indexed,
@@ -69,9 +78,6 @@ from mt5cli.history import create_rate_compatibility_views
 from mt5cli.retry import retry_with_backoff
 from mt5cli.schemas import ensure_utc_columns, normalize_time_columns
 
-if TYPE_CHECKING:
-    from pathlib import Path
-
 
 def _sample_frame(kind: DataKind) -> pd.DataFrame:
     if kind is DataKind.rates:
@@ -547,11 +553,69 @@ class TestStableSdkContract:
         missing = sorted(STABLE_SDK_EXPORTS - set(mt5cli.__all__))
         assert not missing, f"STABLE_SDK_EXPORTS missing from __all__: {missing}"
 
+    def test_public_export_tiers_are_disjoint_and_complete(self) -> None:
+        """Documented public tiers do not overlap and classify root exports."""
+        assert PUBLIC_EXPORT_TIERS == {
+            "stable": STABLE_SDK_EXPORTS,
+            "secondary": SECONDARY_PUBLIC_EXPORTS,
+        }
+        assert not (STABLE_SDK_EXPORTS & SECONDARY_PUBLIC_EXPORTS)
+        tiered_exports = STABLE_SDK_EXPORTS | SECONDARY_PUBLIC_EXPORTS
+        root_exports = set(mt5cli.__all__)
+
+        missing_from_root = sorted(tiered_exports - root_exports)
+        assert not missing_from_root, (
+            f"Tiered exports missing from __all__: {missing_from_root}"
+        )
+
+        tier_metadata_exports = {
+            "PUBLIC_EXPORT_TIERS",
+            "SECONDARY_PUBLIC_EXPORTS",
+            "STABLE_SDK_EXPORTS",
+        }
+        unclassified_root_exports = sorted(
+            root_exports - tiered_exports - tier_metadata_exports,
+        )
+        assert not unclassified_root_exports, (
+            f"Root exports missing from public API tiers: {unclassified_root_exports}"
+        )
+
+    def test_stable_docs_do_not_document_nonstable_exports(self) -> None:
+        """Stable docs do not promote secondary root exports."""
+        docs_path = Path("docs/api/public-contract.md")
+        docs = docs_path.read_text(encoding="utf-8")
+        stable_section = docs.split("## Stable downstream SDK API", maxsplit=1)[
+            1
+        ].split(
+            "## Secondary public exports",
+            maxsplit=1,
+        )[0]
+        documented_symbols = set(
+            re.findall(r"`([A-Za-z_][A-Za-z0-9_]*)`", stable_section)
+        )
+        nonstable_exports = SECONDARY_PUBLIC_EXPORTS
+
+        wrongly_stable = sorted(documented_symbols & nonstable_exports)
+        assert not wrongly_stable, (
+            f"Non-stable exports documented in stable section: {wrongly_stable}"
+        )
+
     @pytest.mark.parametrize("name", sorted(STABLE_SDK_EXPORTS))
     def test_stable_exports_are_importable_from_package_root(self, name: str) -> None:
         """Stable SDK names resolve through ``from mt5cli import ...``."""
         assert hasattr(mt5cli, name), f"{name!r} missing from mt5cli package root"
 
+    @pytest.mark.parametrize(
+        "name",
+        sorted(SECONDARY_PUBLIC_EXPORTS),
+    )
+    def test_secondary_exports_are_importable(
+        self,
+        name: str,
+    ) -> None:
+        """Non-stable public names remain available from the package root."""
+        assert hasattr(mt5cli, name), f"{name!r} missing from mt5cli package root"
+
     def test_drop_forming_rate_bar_from_package_root(self) -> None:
         """Closed-bar trimming is available from the stable package surface."""
         frame = pd.DataFrame({"time": [1, 2, 3], "close": [1.0, 1.1, 1.2]})
@@ -615,6 +679,16 @@ class TestStableSdkContract:
 
         assert calculate_positions_margin(client) == 0
 
+    def test_generic_trading_helpers_from_package_root(self) -> None:
+        """New generic trading helpers resolve through the stable surface."""
+        price = extract_tick_price({"bid": "1.2"}, "bid")
+        assert price is not None
+        assert abs(price - 1.2) < 1e-9
+        assert callable(calculate_trailing_stop_updates)
+        assert callable(calculate_account_projected_margin_ratio)
+        assert callable(calculate_projected_margin_ratio)
+        assert callable(calculate_symbol_group_margin_ratio)
+
     def test_resolve_rate_view_name_from_package_root(self, tmp_path: Path) -> None:
         """Rate view resolution is importable and honors require_existing."""
         db_path = tmp_path / "rates.db"

tests/test_sdk.py

@@ -54,6 +54,7 @@ from mt5cli.sdk import (
     resolve_account_spec,
     resolve_account_specs,
     substitute_env_placeholders,
+    substitute_mapping_values,
     symbol_info,
     symbol_info_tick,
     symbols,
@@ -2436,3 +2437,263 @@ class TestThrottledHistoryUpdater:
             updater.update(MagicMock(), ["EURUSD"])
 
         assert updater.last_update_monotonic is None
+
+
+class TestBuildConfigStringLogin:
+    """Tests for build_config() string login coercion (issue #61)."""
+
+    @pytest.mark.parametrize(
+        ("login", "expected"),
+        [
+            (None, None),
+            (12345, 12345),
+            ("12345", 12345),
+            (" 12345 ", 12345),
+            ("", None),
+            ("   ", None),
+        ],
+    )
+    def test_coerces_login_from_string(
+        self,
+        login: int | str | None,
+        expected: int | None,
+    ) -> None:
+        """Test build_config coerces string login to int or None."""
+        config = build_config(login=login)
+        assert config.login == expected
+
+    def test_rejects_non_numeric_string_login(self) -> None:
+        """Test build_config raises ValueError for non-numeric string login."""
+        with pytest.raises(ValueError, match="invalid literal"):
+            build_config(login="abc")
+
+    def test_expands_dollar_brace_login_with_opt_in(
+        self,
+        monkeypatch: pytest.MonkeyPatch,
+    ) -> None:
+        """Test build_config expands ${MT5_LOGIN} and coerces with opt-in."""
+        monkeypatch.setenv("MT5_LOGIN", "12345")
+        config = build_config(login="${MT5_LOGIN}", allow_whole_dollar_env=True)
+        assert config.login == 12345
+
+    def test_expands_whole_dollar_login_with_opt_in(
+        self,
+        monkeypatch: pytest.MonkeyPatch,
+    ) -> None:
+        """Test build_config expands $MT5_LOGIN and coerces with opt-in."""
+        monkeypatch.setenv("MT5_LOGIN", "99999")
+        config = build_config(login="$MT5_LOGIN", allow_whole_dollar_env=True)
+        assert config.login == 99999
+
+    def test_missing_env_variable_raises(
+        self,
+        monkeypatch: pytest.MonkeyPatch,
+    ) -> None:
+        """Test build_config raises ValueError when referenced env var is not set."""
+        monkeypatch.delenv("MT5_LOGIN", raising=False)
+        with pytest.raises(ValueError, match="'MT5_LOGIN' is not set"):
+            build_config(login="${MT5_LOGIN}", allow_whole_dollar_env=True)
+
+    def test_env_expands_to_blank_becomes_none(
+        self,
+        monkeypatch: pytest.MonkeyPatch,
+    ) -> None:
+        """Test build_config coerces blank env-expanded login to None."""
+        monkeypatch.setenv("MT5_LOGIN", "")
+        config = build_config(login="${MT5_LOGIN}", allow_whole_dollar_env=True)
+        assert config.login is None
+
+    def test_dollar_brace_login_not_expanded_without_opt_in(self) -> None:
+        """Test ${MT5_LOGIN} is not expanded when allow_whole_dollar_env=False."""
+        with pytest.raises(ValueError, match="invalid literal"):
+            build_config(login="${MT5_LOGIN}")
+
+    def test_integer_login_preserved_backward_compat(self) -> None:
+        """Test existing int login callers remain backward-compatible."""
+        config = build_config(login=54321)
+        assert config.login == 54321
+
+    def test_none_login_preserved_backward_compat(self) -> None:
+        """Test existing None login callers remain backward-compatible."""
+        config = build_config(login=None)
+        assert config.login is None
+
+
+class TestSubstituteMappingValues:
+    """Tests for substitute_mapping_values() (issue #62)."""
+
+    def test_substitutes_selected_keys_in_flat_dict(
+        self,
+        monkeypatch: pytest.MonkeyPatch,
+    ) -> None:
+        """Test selected keys are substituted in a flat mapping."""
+        monkeypatch.setenv("MT5_LOGIN", "12345")
+        data: dict[str, object] = {
+            "mt5_login": "${MT5_LOGIN}",
+            "strategy_name": "${MT5_LOGIN}",
+        }
+        result = substitute_mapping_values(data, keys={"mt5_login"})
+        assert result == {"mt5_login": "12345", "strategy_name": "${MT5_LOGIN}"}
+
+    def test_preserves_non_selected_literal_dollar_signs(
+        self,
+        monkeypatch: pytest.MonkeyPatch,
+    ) -> None:
+        """Test literal dollar signs in non-selected fields are preserved exactly."""
+        monkeypatch.setenv("MT5_PASSWORD", "secret")
+        data: dict[str, object] = {
+            "mt5_password": "${MT5_PASSWORD}",
+            "notes": "$NOT_EXPANDED",
+        }
+        result = substitute_mapping_values(data, keys={"mt5_password"})
+        assert result == {"mt5_password": "secret", "notes": "$NOT_EXPANDED"}
+
+    def test_nested_dict_traversal_substitutes_selected_keys(
+        self,
+        monkeypatch: pytest.MonkeyPatch,
+    ) -> None:
+        """Test selected keys inside nested dicts are substituted."""
+        monkeypatch.setenv("MT5_SERVER", "Broker-Demo")
+        data: dict[str, object] = {
+            "outer": {
+                "mt5_server": "${MT5_SERVER}",
+                "other": "${MT5_SERVER}",
+            }
+        }
+        result = substitute_mapping_values(data, keys={"mt5_server"})
+        assert result == {
+            "outer": {"mt5_server": "Broker-Demo", "other": "${MT5_SERVER}"}
+        }
+
+    def test_nested_list_traversal_substitutes_selected_keys(
+        self,
+        monkeypatch: pytest.MonkeyPatch,
+    ) -> None:
+        """Test selected keys inside list elements are substituted."""
+        monkeypatch.setenv("MT5_LOGIN", "42")
+        data: dict[str, object] = {
+            "accounts": [
+                {"mt5_login": "${MT5_LOGIN}", "name": "${MT5_LOGIN}"},
+                {"mt5_login": "${MT5_LOGIN}", "name": "fixed"},
+            ]
+        }
+        result = substitute_mapping_values(data, keys={"mt5_login"})
+        assert result == {
+            "accounts": [
+                {"mt5_login": "42", "name": "${MT5_LOGIN}"},
+                {"mt5_login": "42", "name": "fixed"},
+            ]
+        }
+
+    def test_whole_dollar_expanded_with_opt_in(
+        self,
+        monkeypatch: pytest.MonkeyPatch,
+    ) -> None:
+        """Test $ENV_NAME is expanded when allow_whole_dollar_env=True."""
+        monkeypatch.setenv("MT5_PASSWORD", "secret")
+        data: dict[str, object] = {"mt5_password": "$MT5_PASSWORD"}
+        result = substitute_mapping_values(
+            data,
+            keys={"mt5_password"},
+            allow_whole_dollar_env=True,
+        )
+        assert result == {"mt5_password": "secret"}
+
+    def test_whole_dollar_not_expanded_by_default(
+        self,
+        monkeypatch: pytest.MonkeyPatch,
+    ) -> None:
+        """Test $ENV_NAME in a selected key is preserved when opt-in is False."""
+        monkeypatch.setenv("MT5_PASSWORD", "secret")
+        data: dict[str, object] = {"mt5_password": "$MT5_PASSWORD"}
+        result = substitute_mapping_values(data, keys={"mt5_password"})
+        assert result == {"mt5_password": "$MT5_PASSWORD"}
+
+    def test_blank_string_becomes_none_for_blank_keys(self) -> None:
+        """Test blank strings are normalised to None for blank_string_keys_as_none."""
+        data: dict[str, object] = {
+            "mt5_login": "",
+            "mt5_password": "  ",
+            "other": "",
+        }
+        result = substitute_mapping_values(
+            data,
+            keys=set(),
+            blank_string_keys_as_none={"mt5_login", "mt5_password"},
+        )
+        assert result == {"mt5_login": None, "mt5_password": None, "other": ""}
+
+    def test_env_expanded_blank_becomes_none(
+        self,
+        monkeypatch: pytest.MonkeyPatch,
+    ) -> None:
+        """Test env-expanded blank string is normalised to None."""
+        monkeypatch.setenv("MT5_LOGIN", "")
+        data: dict[str, object] = {"mt5_login": "${MT5_LOGIN}"}
+        result = substitute_mapping_values(
+            data,
+            keys={"mt5_login"},
+            blank_string_keys_as_none={"mt5_login"},
+        )
+        assert result == {"mt5_login": None}
+
+    def test_missing_env_variable_raises_for_selected_key(
+        self,
+        monkeypatch: pytest.MonkeyPatch,
+    ) -> None:
+        """Test missing env var for a selected key raises ValueError."""
+        monkeypatch.delenv("MT5_MISSING", raising=False)
+        data: dict[str, object] = {"mt5_login": "${MT5_MISSING}"}
+        with pytest.raises(ValueError, match="'MT5_MISSING' is not set"):
+            substitute_mapping_values(data, keys={"mt5_login"})
+
+    def test_non_string_values_preserved(self) -> None:
+        """Test non-string values under selected or non-selected keys are preserved."""
+        data: dict[str, object] = {
+            "mt5_login": 12345,
+            "timeout": 5000,
+            "enabled": True,
+            "ratio": 1.5,
+            "nothing": None,
+        }
+        result = substitute_mapping_values(
+            data, keys={"mt5_login", "timeout", "enabled", "ratio", "nothing"}
+        )
+        assert result == data
+
+    def test_caller_supplied_key_set_substitutes_correctly(
+        self,
+        monkeypatch: pytest.MonkeyPatch,
+    ) -> None:
+        """Test helper works with any caller-supplied key set."""
+        monkeypatch.setenv("APP_LOGIN", "77777")
+        monkeypatch.setenv("APP_PASSWORD", "p4ss")
+        data: dict[str, object] = {
+            "app_login": "${APP_LOGIN}",
+            "app_password": "${APP_PASSWORD}",
+            "unrelated": "${APP_LOGIN}",
+        }
+        credential_keys = {"app_login", "app_password"}
+        result = substitute_mapping_values(data, keys=credential_keys)
+        assert result == {
+            "app_login": "77777",
+            "app_password": "p4ss",
+            "unrelated": "${APP_LOGIN}",
+        }
+
+    def test_scalar_data_returned_unchanged(self) -> None:
+        """Test a scalar (non-dict, non-list) value is returned as-is."""
+        assert substitute_mapping_values("hello", keys={"x"}) == "hello"
+        assert substitute_mapping_values(42, keys={"x"}) == 42
+        assert substitute_mapping_values(None, keys={"x"}) is None
+
+    def test_tuple_container_not_traversed(
+        self,
+        monkeypatch: pytest.MonkeyPatch,
+    ) -> None:
+        """Test tuple containers are returned as-is without traversal."""
+        monkeypatch.setenv("MT5_LOGIN", "42")
+        data: dict[str, object] = {"accounts": ({"mt5_login": "${MT5_LOGIN}"},)}
+        result = substitute_mapping_values(data, keys={"mt5_login"})
+        # tuple is returned as-is; inner dict is NOT visited
+        assert result == {"accounts": ({"mt5_login": "${MT5_LOGIN}"},)}

uv.lock

@@ -487,7 +487,7 @@ wheels = [
 
 [[package]]
 name = "mt5cli"
-version = "0.9.1"
+version = "0.9.5"
 source = { editable = "." }
 dependencies = [
     { name = "click" },