Issues

MCP: `DynamicDash` Markdown (display-only) form fields are put on the drive contract — `describe_app` lists them as inputs, `set_input` accepts them, and `invoke` forwards them into the callback (crash). A fresh `placeholder` app exposes its `_hint` as the sole "input".

bug

routine

#220

· dkedar7 opened

on Aug 28, 2026

A `range()`-default Slider (`int = range(0,10)`) renders with no initial `value`, so a default Run passes `None` and a type-faithful callback crashes — plus the slider `max` is off-by-one (accepts `range.stop`, which `range()` never yields)

bug

routine

#219

· dkedar7 opened

on Aug 27, 2026

MCP `describe_app` types a `DateRange` input as `type: "string"`, but its value is a two-element list of ISO dates — the contract self-contradicts (`current_value` is a list under `type:"string"`) and `set_input`/`invoke` accept a bare string the range picker can never emit

bug

routine

#218

· dkedar7 opened

on Aug 26, 2026

A callback that returns a rich type (Figure / DataFrame / Image) but omits the return-type annotation renders a silently BLANK output — no error, "Run to see results" never clears (a `str` return works, and MCP `invoke` runs the same callback fine)

bug

routine

#217

· dkedar7 opened

on Aug 25, 2026

MCP `set_inputs` is not atomic — a partially-invalid batch returns `ok:false` yet mutates the valid subset, while `invoke(inputs=...)` with the SAME dict rejects everything. Identical input, divergent state.

bug

routine

#216

· dkedar7 opened

on Aug 24, 2026

Chat: a `chat=True` callback whose first parameter isn't named `query` fails with a misleading `ImportError: fast-dash[agent]` instead of the documented "first parameter must be `query`" message — misdirecting anyone who follows the 5-line-chatbot docs but mistypes the composer param

bug

routine

#214

· dkedar7 opened

on Aug 23, 2026

A `steps=` pipeline app throws an unhandled 500 on every page load — `toggle_sidebar` reads `self.app.inputs`, which `_init_steps` never sets (`AttributeError: 'FastDash' object has no attribute 'inputs'`)

bug

routine

#213

· dkedar7 opened

on Aug 22, 2026

`stream=True` + a `yield`/generator callback hard-crashes the web-UI Run with an unhandled 500 (`Object of type generator is not JSON serializable`) — the streaming path never consumes the generator (contradicts #207's "the UI streams tick 1/2/3")

bug

routine

#212

· dkedar7 opened

on Aug 21, 2026

Docs undersell the agent-chat extra: `pip install "fast-dash[agent]"` is not enough — the auto-built assistant also needs the undocumented `fast-dash[langstage]`, so the README's "Give the agent tools" snippet raises ImportError as written

bug

routine

#211

· dkedar7 opened

on Aug 20, 2026

Public API still advertises the defunct `mcp_port=8001` / `mcp_host='127.0.0.1'` kwargs (no-ops) — the `mcp_port` default contradicts the "same port /mcp" docs and points a signature-reading user at a dead port

bug

routine

#210

· dkedar7 opened

on Aug 19, 2026

MCP: a `datetime.date` (`DateInput`) input accepts any non-ISO / impossible date string — `set_input` returns `ok:true`, then `invoke` crashes with a raw `AttributeError`. The date builtin-hint path has no validation (unlike Slider/Select), breaking the "contract is enforced" invariant

bug

routine

#209

· dkedar7 opened

on Aug 18, 2026

MCP parity gap: a human UI Run's OUTPUT is never mirrored to the agent — `describe_app` shows the input a human set but not the output it produced (input mirror is bidirectional, output mirror is server→browser only)

bug

routine

#208

· dkedar7 opened

on Aug 17, 2026

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All issues

MCP: `DynamicDash` Markdown (display-only) form fields are put on the drive contract — `describe_app` lists them as inputs, `set_input` accepts them, and `invoke` forwards them into the callback (crash). A fresh `placeholder` app exposes its `_hint` as the sole "input".

A `range()`-default Slider (`int = range(0,10)`) renders with no initial `value`, so a default Run passes `None` and a type-faithful callback crashes — plus the slider `max` is off-by-one (accepts `range.stop`, which `range()` never yields)

MCP `describe_app` types a `DateRange` input as `type: "string"`, but its value is a two-element list of ISO dates — the contract self-contradicts (`current_value` is a list under `type:"string"`) and `set_input`/`invoke` accept a bare string the range picker can never emit

A callback that returns a rich type (Figure / DataFrame / Image) but omits the return-type annotation renders a silently BLANK output — no error, "Run to see results" never clears (a `str` return works, and MCP `invoke` runs the same callback fine)

MCP `set_inputs` is not atomic — a partially-invalid batch returns `ok:false` yet mutates the valid subset, while `invoke(inputs=...)` with the SAME dict rejects everything. Identical input, divergent state.

Chat: a `chat=True` callback whose first parameter isn't named `query` fails with a misleading `ImportError: fast-dash[agent]` instead of the documented "first parameter must be `query`" message — misdirecting anyone who follows the 5-line-chatbot docs but mistypes the composer param

A `steps=` pipeline app throws an unhandled 500 on every page load — `toggle_sidebar` reads `self.app.inputs`, which `_init_steps` never sets (`AttributeError: 'FastDash' object has no attribute 'inputs'`)

`stream=True` + a `yield`/generator callback hard-crashes the web-UI Run with an unhandled 500 (`Object of type generator is not JSON serializable`) — the streaming path never consumes the generator (contradicts #207's "the UI streams tick 1/2/3")

Docs undersell the agent-chat extra: `pip install "fast-dash[agent]"` is not enough — the auto-built assistant also needs the undocumented `fast-dash[langstage]`, so the README's "Give the agent tools" snippet raises ImportError as written

Public API still advertises the defunct `mcp_port=8001` / `mcp_host='127.0.0.1'` kwargs (no-ops) — the `mcp_port` default contradicts the "same port /mcp" docs and points a signature-reading user at a dead port

MCP: a `datetime.date` (`DateInput`) input accepts any non-ISO / impossible date string — `set_input` returns `ok:true`, then `invoke` crashes with a raw `AttributeError`. The date builtin-hint path has no validation (unlike Slider/Select), breaking the "contract is enforced" invariant

MCP parity gap: a human UI Run's OUTPUT is never mirrored to the agent — `describe_app` shows the input a human set but not the output it produced (input mirror is bidirectional, output mirror is server→browser only)

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