History panel: edit interactive fits in step-by-step replay #497

Current behavior

Interactive fits (Processing > Fitting > Interactive fitting) are recorded in the History panel as recompute_fit UI actions holding the canonical fit_params of the accepted fit (__row_compute_fit).

• Replay recomputes the fitted curve in place from these parameters through sigima.tools.signal.fitting.evaluate_fit, for every built-in fit type.
• Step-by-step replay never opens the fit dialog. When the interactive fit action is selected alone, DataLab shows "Interactive fits cannot be edited from the History panel: the fit dialog cannot be reopened with the recorded parameters. The recorded fit is kept as is." and leaves the fit unchanged (recompute_fit, report_non_editable); within a session, the fit is recomputed with its recorded parameters. This behavior is covered by test_interactive_fit_records_replays_in_place_and_refuses_edit.

The parameters of an interactive fit therefore cannot be reviewed or adjusted from the History panel: the only way to change them is to run the fit again, which creates a new curve and a new history entry instead of updating the recorded ones and their downstream actions.

Expected behavior

Step-by-step replay of an interactive fit action reopens the same fit dialog on the source signal, starting from the recorded fit_params (no automatic fit on opening; the Auto fit button stays available).

• Accepting the dialog updates the recorded fit_params and the fitted curve in place (same UUID), and the edit propagates to the downstream dependent actions, as for the other actions edited step by step.
• Cancelling the dialog stops the replay, as for the other step-by-step dialogs.

Dependency

The SigimaX fit dialogs cannot be opened with given parameter values yet: this requires step 2 of DataLab-Platform/SigimaX#3 (open the dialog matching a canonical fit_params dict and return the updated dict on acceptance), planned for SigimaX 1.2.0.

Proposed implementation

• In recompute_fit(edit=True), open the SigimaX dialog matching fit_params["fit_type"] with the recorded parameters instead of the information message, then store the returned fit_params in the action.
• The mapping from canonical fit types to dialogs ("doubleexponential" → piecewise exponential dialog, "linear"/"polynomial" with the degree given by the number of coefficients, multi-peak types with their recorded peak positions x0_i) should be provided by SigimaX rather than duplicated in DataLab.
• Fit actions recorded by earlier versions (including .dlhist files and workspaces) already hold canonical fit_params: they become editable without migration.

Tests

• Adapt test_interactive_fit_records_replays_in_place_and_refuses_edit: step-by-step replay opens the dialog (deterministic stand-in in tests) with the recorded parameters, updates the fitted curve in place and the recorded fit_params, and recomputes the downstream actions; cancelling leaves the fit untouched.
• A multi-peak fit keeps its recorded peak positions x0_i after an edit.

Notes

• The information message above (and its French translation) becomes obsolete.
• Update the Step-by-step description in the History panel documentation (doc/features/common/historypanel.rst).