[Diff since v9.65.0](v9.65.0...v9.66.0)

**Merged pull requests:**
- feat: `ImplicitDiscreteSystem` (#3386) (@vyudu)
- fix: fix `DEF` parameters for `split = true, flatten = false` systems (#3403) (@AayushSabharwal)
- feat: implement `SciMLBase.detect_cycles` (#3427) (@AayushSabharwal)
- fix: fix symbolic maps given to `linearize`, warn in `linearization_function` (#3432) (@AayushSabharwal)
- feat: support analysis points duplicating existing connections (#3453) (@AayushSabharwal)
- Fix: Make `build explicit observed function` return Expr when `expression=true` (#3454) (@ashutosh-b-b)
- test: relax initializationsystem test (#3455) (@AayushSabharwal)
- fix: don't use `===` for comparison in variable metadata tests (#3463) (@AayushSabharwal)
- build: bump minor version (#3465) (@AayushSabharwal)

**Closed issues:**
- ImplicitDiscreteSystem (#2077)
- `complete(sys; flatten=false)` creates unexpected DEF parameters (#3322)
- `DEF` in parameters (#3401)
- Strange error when evaluating the Jacobian for certain systems (#3447)
- ODEFunction from the same ODESystem gives inconsistent ODE solve result (#3450)
- Can create `NonlinearProblem` with missing variables (#3461)
- Strange `DEF` parameter appears in `parameter(sys)` for certain systems (#3464)

[Diff since v9.64.3](v9.64.3...v9.65.0)

**Merged pull requests:**
- Replace Expronicon with Moshi (#3354) (@visr)
- fix(nonlinearsystem): Fix codegen issue for vector parameters (#3382) (@SebastianM-C)
- feat: run trivial initialization in problem constructor (#3404) (@AayushSabharwal)
- docs: add doc page for FMU import capability (#3405) (@AayushSabharwal)
- fix: allow passing guesses to `linearize`, improve linearization docs (#3412) (@AayushSabharwal)
- feat: add `map_variables_to_equations` (#3417) (@AayushSabharwal)
- feat: add `isInitial` (#3433) (@vyudu)
- CompatHelper: add new compat entry for FMI at version 0.14 for package docs, (keep existing compat) (#3434) (@github-actions[bot])
- CompatHelper: add new compat entry for FMIZoo at version 1 for package docs, (keep existing compat) (#3435) (@github-actions[bot])
- fix: separate `Initial` parameters into `initials` portion (#3439) (@AayushSabharwal)
- feat: allow `NonlinearSystem(::ODESystem)` and `NonlinearProblem(::ODESystem)` (#3440) (@AayushSabharwal)

**Closed issues:**
- Trivial initialization problem isn't solved when creating `ODEProblem` (#3290)
- `remake` failures (#3396)
- Add ability to provide additional guesses to `linearize` and family (#3400)
- `remake` issues (#3410)
- Cases of creation of `NonlinearSystem`s have been broken (#3411)
- SciMLBase - equations bug fixed, but introduces new problems (#3421)
- isInitial function (#3431)
- Faulty non-boolean error in ifelse() (#3441)
- Broken amount of parameters: much more parameters in resulting ODEProblem than symbolic parameters in MTK system (#3444)

[Diff since v9.64.2](v9.64.2...v9.64.3)

**Merged pull requests:**
- fix: fix `SCCNonlinearProblem` reordering parameters (#3425) (@AayushSabharwal)
- build: bump patch version (#3426) (@AayushSabharwal)

**Closed issues:**
- Conditional branches inside `@component` statements do not support multiple components (#3424)

[Diff since v9.64.1](v9.64.1...v9.64.2)

**Merged pull requests:**
- add utilities and tests for disturbance modeling (#3314) (@baggepinnen)
- BVProblem with constraints (#3323) (@vyudu)
- fix: validate u0map and pmap (#3350) (@vyudu)
- Renaming discrete variables during structural simplification (plus refactoring `tearing_reassemble`) (#3379) (@vyudu)
- fix: fix array varables split across SCCs in SCCNonlinearProblem (#3384) (@AayushSabharwal)
- refactor: rewrite `HomotopyContinuationProblem` to target NonlinearSolveHomotopyContinuation.jl (#3385) (@AayushSabharwal)
- refactor: format (#3413) (@AayushSabharwal)
- fix: make the diffvar type check less restrictive  (#3415) (@vyudu)
- feat: mark `getproperty(::AbstractSystem, ::Symbol)` as non-differentiable (#3422) (@AayushSabharwal)
- Replace `vcat(eqs...)` with `reduce(vcat, eqs)` (#3423) (@devmotion)

**Closed issues:**
- Nonsensical stuff is allowed in input paraemter maps (#3325)
- Calling reinit! makes the solver unstable (#3375)
- Solution somehow corrupted with `IfLifting` (#3383)
- Diffvar type check introduced in v9.63 causes error with complex diffvars (#3406)
- Re-creating MTK problems causes side effects (#3407)
- Can no longer simulate coupled `ReactionSystem` `ODESystem` (#3409)
- `equations` not defined??? (#3414)

[Diff since v9.64.0](v9.64.0...v9.64.1)

**Merged pull requests:**
- fix: fix several bugs (#3390) (@AayushSabharwal)
- build: bump patch version (#3402) (@AayushSabharwal)

**Closed issues:**
- Parameter splitting breaks runtime generated jacobians (#3294)
- Cases where `remake` seems to be mutating the original input in some way (#3395)
- breaking change in behavior of complete in non-breaking release (#3397)

[Diff since v9.63.0](v9.63.0...v9.64.0)

**Merged pull requests:**
- CompatHelper: add new compat entry for PreallocationTools at version 0.4 for package docs, (keep existing compat) (#3388) (@github-actions[bot])
- fix: allow vector of parameters for split system of pure tunables (#3389) (@AayushSabharwal)

[Diff since v9.62.0](v9.62.0...v9.63.0)

**Merged pull requests:**
- fix: Add metadata getters (#3334) (@vyudu)
- Validate types of state variables in ODESystem/SDESystem construction (#3340) (@vyudu)
- feat: always build initialization problem (#3347) (@AayushSabharwal)
- fix: handle scalarized array parameters in initialization (#3358) (@AayushSabharwal)
- refactor: centralize all code generation (#3360) (@AayushSabharwal)
- refactor: format (#3361) (@AayushSabharwal)
- Add @description to @mtkmodel (#3363) (@hersle)
- feat: add `assertions` functionality (#3364) (@AayushSabharwal)
- latexify equation (#3366) (@owiecc)
- refactor: default `create_bindings` to false in `build_function_wrapper` (#3367) (@AayushSabharwal)
- Fix parameter array handling in ImperativeAffect (#3368) (@BenChung)
- Fix `@mtkbuild` macro keyword parsing (#3371) (@AayushSabharwal)
- Support specialization in `ODEFunctionExpr` (#3373) (@devmotion)
- test: update reference tests (#3377) (@AayushSabharwal)
- add documentation page for `DiscreteSystem` (#3380) (@vyudu)
- build: bump minor version (#3387) (@AayushSabharwal)

**Closed issues:**
- It is possible to designate non-default types for variables, which are then ignored. (#2589)
- Missing metadata getters (#2643)
- Initialization System fails to remove an equation (#3312)
- `remake` ignores `u0` updates when the initialization is trivial (#3318)
- Operating point passed to `linearization_function` closure has no effect (#3319)
- MTK does not allow building initialization systems for un-simplified systems (#3330)
- Initialization warning when creating certain `SDEProblem`s from Catalyst (but not corresponding `ODEProblem`s (#3331)
- Remake does not handle dual type promotion with dummy derivatives (#3336)
- Cannot solve ODE with Duals if it has initialization and callback (#3342)
- Determined complete system raises an overdetermined warn when creating ODEProblem (#3349)
- Initialization and Linearization (#3352)
- `ODESystem` not dealing with dynamic parameters (#3365)
- The `IfLifting` pass doesn't seem to be working quite right (#3369)

[Diff since v9.61.0](v9.61.0...v9.62.0)

**Merged pull requests:**
- feat: add `FMUComponent` (#3282) (@AayushSabharwal)
- test: added tests for SDEFunctionExpr (#3313) (@sivasathyaseeelan)
- Handle events in `isequal` (#3317) (@vyudu)
- fix: fix `add_fallbacks!` (#3332) (@AayushSabharwal)
- Start using Moshi compatible syntax for singleton ADT variants (#3353) (@visr)

**Closed issues:**
- Systems are considered equal, even if they have different events  (#2638)
- remake failing for several cases with vector variables (#2660)
- `remake` not working for Symbol + array variable (`u0` only, `p` is fine) (#3281)
- ERROR: ArgumentError: ... is neither an observed nor an unknown variable (#3355)

[Diff since v9.60.0](v9.60.0...v9.61.0)

**Merged pull requests:**
- fix: `@mtkmodel` no longer makes `@variables` callable (#3217) (@AayushSabharwal)
- fix: properly handle rational functions in HomotopyContinuation (#3265) (@AayushSabharwal)
- feat: better inbounds handling and propagation for generated functions (#3277) (@AayushSabharwal)
- feat: add analysis points (#3285) (@AayushSabharwal)
- fix: minor bug fix in `PolynomialTransformation` (#3293) (@AayushSabharwal)
- Generic mechanism for debugging/logging functions (#3296) (@hersle)
- feat: allow remade initialization systems to be incomplete (#3301) (@AayushSabharwal)
- feat: add support for causal connections of variables (#3304) (@AayushSabharwal)
- DifferentialEquations -> OrdinaryDiffEqDefaults in readme (#3305) (@TorkelE)
- Add better SDESystem error when it hasn't been `structural_simplify` (#3316) (@vyudu)
- feat: support caching of different types of subexpressions in `SCCNonlinearProblem` (#3324) (@AayushSabharwal)
- fix: fix initialization of `DiscreteProblem(::JumpSystem)` (#3329) (@AayushSabharwal)
- test: added test for dae_order_lowering (#3335) (@sivasathyaseeelan)
- Fix dual type promotion in remake with dummy derivatives (#3337) (@hersle)
- fix: respect `checkbounds` in `build_explicit_observed_function` (#3339) (@AayushSabharwal)
- fix: only solve parameter initialization for `NonlinearSystem` (#3345) (@AayushSabharwal)

**Closed issues:**
- `SDESystem`'s not displayed properly with latexify (#2069)
- Wonky interface for Dicrete/Continious callbacks when using ModelingToolkit (#2303)
- Events not working with automatic solver selection (#2741)
- Latexify display does not work for `SDESystem`s (#2782)
- SDEs with brownian motions requires `structural_simplify` (#2831)
- Regression: Problem with indexing of JumpProblem (#2838)
- support connections between (causal) variables `connect(var1, var2)` (#3287)
- HomotopyContinuation extension of MTK breaks creation of ODESystems in PEtab.jl (#3291)
- Cannot `remake` problems if not providing full `u0` and the first version did not require an initialization problem (#3295)
- Parameter initial conditions broken for `DiscreteProblem`s (#3297)
- `deepcopy` leads to a failure in the initialization (#3307)
- Circular dependencies on Julia 1.10 (#3308)
- Dropped Variable (#3311)
- Some new problems with `remake` for Catalyst update  (#3326)

[Diff since v9.59.0](v9.59.0...v9.60.0)

**Merged pull requests:**
- feat: create initialization systems for all problem types (#3253) (@AayushSabharwal)
- fix: fix `timeseries_parameter_index` for array symbolics (#3284) (@AayushSabharwal)
- build: bump OrdinaryDiffEqDefault compat (#3286) (@AayushSabharwal)
- build: bump minor version (#3289) (@AayushSabharwal)