[T4rk1n]

update_title is documented as accepting None or '' to leave document.title alone during callbacks, and the renderer already handles it (test_rdls003_update_title covers both), but the hint was str, so pyright and mypy rejected Dash(update_title=None).

• Type update_title as Optional[str] in Dash.__init__.
• Match the renderer config type (string | null).
• Add test_typi003_dash_constructor_typing: the None case fails under pyright before the change and passes after.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

Dash performance benchmarks

✅ all within thresholds

	scenario	metric	p90 (ms)	median	growth	baseline p90	note
✅	callback_chain	chain_ms	417.5	410.9	0.94x	499.1
✅	callback_chain	graph_ms	3.2	3.2	1.0x	2.4
✅	callback_fanout	fanout_ms	84.6	78.1	0.88x	92.5
✅	deep_nesting	render_ms	55.3	51.6	1.01x	56.8
✅	full_children_replace	replace_ms	5424.7	1905.9	18.64x	4697.1
✅	initial_render_large	render_ms	588.4	565.5	1.02x	694.4
✅	initial_render_small	render_ms	101.2	92.6	0.98x	104.0
✅	patch_append_nested	append_ms	116.0	87.7	2.29x	192.3
✅	patch_append_toplevel	append_ms	110.2	82.8	1.98x	140.2
✅	patch_scalar_update_large	update_ms	153.6	145.5	0.94x	202.9
✅	wildcard_all_resolve	wildcard_ms	302.8	293.0	0.95x	313.6
✅	wildcard_all_resolve	graph_ms	1.3	1.3	1.0x	1.3

growth = late-third / early-third per-op time; ~1 is flat, a large value means the per-op cost scales with accumulated state.

machine scale vs baseline: 0.96x - divided out of the baseline ratios so they compare like for like (the absolute warn/fail ceilings are left un-scaled); calibrated on initial_render_small.