speckit-evidence-graph

name	speckit-evidence-graph
description	Validate and render the task DAG; compute synthetic propagation.
compatibility	Requires spec-kit project structure with .specify/ directory
metadata	{"author":"github-spec-kit","source":"evidence:commands/speckit.evidence.graph.md"}

/speckit.graph.compute

Parse specs/<feature>/tasks.md and specs/<feature>/tasks.deps.yml, validate the graph (acyclic, no dangling refs, every id present in both files), and render readiness/task-graph.json + readiness/task-graph.md.

How to invoke

.specify/extensions/evidence/scripts/python/compute-task-graph.py specs/<FEATURE_ID>

or via the audit runner in graph-only mode:

.specify/extensions/evidence/scripts/bash/run-audit.sh specs/<FEATURE_ID> --graph-only

When to run

• Right after /speckit.tasks — confirms the initial DAG is well-formed before implementation begins.
• After every status change during /speckit.implement — refreshes [S*] propagation cheaply.
• Automatically as the before_implement hook (declared in the evidence extension's extension.yml) — refuses to start implement on a broken graph.

What it validates

• Every Tnnn in tasks.md has a matching key in tasks.deps.yml.
• Every Tnnn in tasks.deps.yml has a matching task line in tasks.md.
• Every dep reference resolves to a known Tnnn.
• The graph is acyclic.
• No task depends on itself.

What it computes

Effective status per task, under the propagation rule:

effective(T) =
    synthetic      if declared(T) == synthetic
    auto-synthetic if declared(T) == done AND any dep is (auto-)synthetic
    declared(T)    otherwise

Phase-checkpoint edges are auto-injected (every task in Phase N+1 gets an implicit edge to the last foundation task of Phase N). These do not appear in tasks.deps.yml and do not need to be written by hand.

On failure

The script exits non-zero and writes the errors into task-graph.md's verdict block. Do not proceed with /speckit.implement until the graph is clean.

Common failure modes and their fixes:

• Dangling ref — tasks.deps.yml references Tnnn that isn't in tasks.md. Add the task line or remove the ref.
• Orphaned key — tasks.deps.yml has a key for Tnnn that isn't in tasks.md. Remove the key or add the task line.
• Cycle — a set of tasks transitively depend on each other. The error message names the cycle path. Break it by removing one edge.
• Duplicate task id — the same Tnnn appears twice in tasks.md. Renumber one.

Output

• specs/<FEATURE_ID>/readiness/task-graph.json — structured state.
• specs/<FEATURE_ID>/readiness/task-graph.md — mermaid diagram, ASCII view, status counts, propagation report with root-cause annotations.

Commit both files alongside the feature's other artifacts.