[Forge] Metabolic pathway flux pipeline - gene KO to COBRApy FBA/FVA to flux-shift artifact open

Effort: thorough

Goal

Build a metabolic-pathway flux pipeline using cobrapy that takes
a gene knock-out (or knock-down expression change), simulates the
resulting metabolic flux in a context-specific genome-scale model
(Recon3D for human or species-appropriate alternative), runs FBA
(Flux Balance Analysis) and FVA (Flux Variability Analysis), and
persists the per-reaction flux shift as an interpretable artifact.
Used by metabolic-vertical debates ("does GLP-1R agonism shift hepatic
gluconeogenesis fluxes?") to provide quantitative answers, not just
literature claims.

Why this matters

The metabolic vertical needs more than DEG analysis to be credible —
fluxes through the metabolic network are what physiologically matter,
and constraint-based modeling is the only tractable way to estimate
them at scale. cobrapy is bundled but no pipeline composes it. With
this pipeline, a metabolic Theorist can argue from simulated fluxes,
the Skeptic can rerun with alternative constraints, and the resulting
artifact is reproducible.

Acceptance Criteria

- load_model(name='Recon3D') — caches Recon3D SBML and
returns a cobra.Model; supports iJO1366 (E. coli) and
iCHOv1 (CHO) as alternatives.
- apply_knockout(model, gene_symbol) — translates gene to
reactions via the model's GPR; sets bounds to 0; returns
modified copy.
- apply_expression(model, gene_to_fold_change) — bulk-applies
a fold-change dict via E-Flux scaling (constraint = baseline
× log1p(fold_change)).
- run_fba(model) — solves; returns objective value + fluxes.
- run_fva(model, fraction_of_optimum=0.95) — solves FVA;
returns per-reaction min/max bounds.
- compare(baseline, perturbed) — computes per-reaction
flux shift, ranks by absolute change, identifies subsystems
with concentrated effect.
- pipeline(gene_or_expression, model='Recon3D') — composes
and commits artifact under
data/scidex-artifacts/flux/<run_id>/ with the SBML
snapshot, flux JSON, and an Escher map highlighting the
top-shifted subsystem. perturbation_kind TEXT CHECK IN ('knockout','expression'),
perturbation_spec_json, baseline_objective, perturbed_objective,
n_reactions_changed, top_subsystem, pipeline_version,
started_at, finished_at, artifact_id). @log_tool_call. generator infrastructure can produce SVG); ranked-reaction
table next to it. (q-vert-vertical-personas-pack) receives a flux_block when
a hypothesis names a gene with a recent flux run. on Recon3D completes <2 min; reports altered glycolysis +
pentose-phosphate fluxes (sanity check); artifact registered. drops growth objective to ~0; non-essential KO leaves
objective unchanged.

Approach

Recon3D pulled from BiGG (http://bigg.ucsd.edu/static/models/Recon3D.xml)

— cache under data/cobra/Recon3D.xml.

E-Flux is a simple constraint scaling — implement once.

Escher map rendering uses escher Python lib if installable,

else SVG via cobra's basic plotter.

The pipeline composes well with q-tool-singlecell-trajectory-

pipeline — single-cell DEG output can drive a per-cell-type
E-Flux run.

Persona injection mirrors the DepMap pattern.

Dependencies

• cobrapy skill.
• Recon3D model (one-time download).
• q-vert-vertical-personas-pack — metabolic-expert persona consumes

the flux_block.

Work Log