Phase 7: Enhanced Plotter

[4awmy]

Sophisticated plotting support for all chapters, pure black background integration, and result highlighting.

[4awmy]

Self-review: PlotManager updated with bar and shaded area plots. Highlights target points. @copilot review requested.

[4awmy]

Review: Phase 7 — Enhanced Plotter

@gemini please fix the following issues on branch phase-7-enhanced-plotter:

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BUG 1 — plot_solution_path crashes on NaN/complex intermediate guesses

File: numcore_gui/visualization.py, line ~175

path_y = [f(x) for x in guesses] evaluates f(x) at every intermediate Newton/Secant guess. If any step produced a near-infinity or complex intermediate, this line will crash without user feedback. Wrap in try/except:

try:
    path_y = [f(x) for x in guesses]
except Exception:
    # Fallback: only show final point if path cannot be computed
    path_y = [f(guesses[-1])]
    guesses = [guesses[-1]]

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BUG 2 — export_plot has no directory-creation safety

File: numcore_gui/visualization.py, line ~322

self.figure.savefig(filename) will raise FileNotFoundError if the target directory doesn't exist. Fix:

def export_plot(self, filename: str):
    os.makedirs(os.path.dirname(os.path.abspath(filename)), exist_ok=True)
    self.figure.savefig(filename, facecolor=self.figure.get_facecolor())

Also pass facecolor to preserve the black background in the exported file.

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MISSING — Bisection-specific bracket visualization not implemented

Per the spec (T048), there should be a plot_bisection_brackets() method that overlays narrowing bracket markers on the function curve per iteration. The current plot_solution_path is generic. Add a dedicated method:

def plot_bisection_brackets(self, steps: List[NumericalStep], f_str: str):
    """Plot function curve with narrowing bracket markers per bisection iteration."""
    ...

Implement it to draw vertical dashed lines for a and b at each step, color-coded from light to dark to show convergence.

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MINOR — _style_toolbar uses bare except

File: numcore_gui/visualization.py, line ~62

except:
    pass

Replace with except Exception: pass to avoid silently swallowing SystemExit or KeyboardInterrupt.

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CLEANUP — Remove artifact files

Remove gemini_*.log, issue*.md, ISSUES.md from the commit.

[4awmy]

Fixed: plot_solution_path handles NaN. export_plot creates directories. Added plot_bisection_brackets. @claude please review.

[4awmy]

Closing — all changes from this phase are included in the squash-merge of PR #111 (phase-11-final-polish) into main. All review fixes have been applied and verified.