Propagate Design Change
When a GDD changes, architectural decisions written against it may no longer be
valid. This skill finds every affected ADR, compares what the ADR assumed against
what the GDD now says, and guides the user through resolution.
Usage: /propagate-design-change design/gdd/combat-system.md
1. Validate Argument
A GDD path argument is required. If missing, fail with:
"Usage: /propagate-design-change design/gdd/[system].md
Provide the path to the GDD that was changed."
Verify the file exists. If not, fail with:
"[path] not found. Check the path and try again."
2. Read the Changed GDD
Read the current GDD in full.
3. Read the Previous Version
Run git to get the previous committed version:
git show HEAD:design/gdd/[filename].md
If the file has no git history (new file), report:
"No previous version in git — this appears to be a new GDD, not a revision.
Nothing to propagate."
If git returns the previous version, do a conceptual diff:
- Identify sections that changed (new rules, removed rules, modified formulas,
changed acceptance criteria, changed tuning knobs)
- Identify sections that are unchanged
- Produce a change summary:
## Change Summary: [GDD filename]
Date of revision: [today]
Changed sections:
- [Section name]: [what changed — new rule, removed rule, formula modified, etc.]
Unchanged sections:
- [Section name]
Key changes affecting architecture:
- [Change 1 — likely to affect ADRs]
- [Change 2]
4. Load Architecture Inputs
Read all ADRs in docs/architecture/:
- For each ADR, read the full file
- Extract the "GDD Requirements Addressed" table
- Note which GDD documents and requirement IDs each ADR references
Read docs/architecture/architecture-traceability.md if it exists.
Report: "Loaded [N] ADRs. [M] reference [gdd filename]."
5. Impact Analysis
For each ADR that references the changed GDD:
Compare the ADR's "GDD Requirements Addressed" entries against the changed sections
of the GDD. For each referenced requirement:
- Locate the requirement in the current GDD — does it still exist?
- Compare: What did the GDD say when the ADR was written vs. what it says now?
- Assess the ADR decision: Is the architectural decision still valid?
Classify each affected ADR as one of:
| Status | Meaning |
|---|
| ✅ Still Valid | The GDD change doesn't affect what this ADR decided |
| ⚠️ Needs Review | The GDD change may affect this ADR — human judgment needed |
| 🔴 Likely Superseded | The GDD change directly contradicts what this ADR assumed |
For each affected ADR, produce an impact entry:
### ADR-NNNN: [title]
Status: [Still Valid / Needs Review / Likely Superseded]
What the ADR assumed about this GDD:
"[relevant quote from the ADR's GDD Requirements Addressed section]"
What the GDD now says:
"[relevant quote from the current GDD]"
Assessment:
[Explanation of whether the ADR decision is still valid, and why]
Recommended action:
[Keep as-is | Review and update | Mark Superseded and write new ADR]
6. Present Impact Report
Present the full impact report to the user before asking for any action. Format:
## Design Change Impact Report
GDD: [filename]
Date: [today]
Changes detected: [N sections changed]
ADRs referencing this GDD: [M]
### Not Affected
[ADRs referencing this GDD whose decisions remain valid]
### Needs Review ([count])
[ADRs that may need updating]
### Likely Superseded ([count])
[ADRs whose assumptions are now contradicted]
6b. Director Gate — Technical Impact Review
Review mode check — apply before spawning TD-CHANGE-IMPACT:
solo → skip. Note: "TD-CHANGE-IMPACT skipped — Solo mode." Proceed to Phase 7.lean → skip. Note: "TD-CHANGE-IMPACT skipped — Lean mode." Proceed to Phase 7.full → spawn as normal.
Spawn technical-director via Task using gate TD-CHANGE-IMPACT (.claude/docs/director-gates.md).
Pass: the full Design Change Impact Report from Phase 6 (change summary, all affected ADRs with their Still Valid / Needs Review / Likely Superseded classifications, and recommended actions).
The technical-director reviews whether:
- The impact classifications are correct (no ADRs under-classified)
- The recommended actions are architecturally sound
- Any cascading effects on other ADRs or systems were missed
Apply the verdict:
- APPROVE → proceed to Phase 7 resolution workflow
- CONCERNS → surface the specific ADRs or recommendations flagged; use
AskUserQuestion with options: Revise the impact assessment / Accept with noted concerns / Discuss further
- REJECT → do not proceed to resolution; re-analyze the impact before continuing
7. Resolution Workflow
For each ADR marked "Needs Review" or "Likely Superseded", ask the user what to do:
Ask for each ADR in turn:
"ADR-NNNN ([title]) — [status]. What would you like to do?"
Options:
- "Mark Superseded (I'll write a new ADR)" — updates ADR status line to
Superseded by: [pending]
- "Update in place (minor revision)" — opens the ADR for editing; note what to revise
- "Keep as-is (the change doesn't actually affect this decision)"
- "Skip for now (revisit later)"
For ADRs marked Superseded:
- Update the ADR's Status field:
Superseded by ADR-[next number] (pending — see change-impact-[date]-[system].md)
- Ask: "May I update the status in [ADR filename]?"
8. Update Traceability Index
If docs/architecture/architecture-traceability.md exists:
- Add the changed GDD requirements to the "Superseded Requirements" table:
## Superseded Requirements
| Date | GDD | Requirement | Changed To | ADRs Affected | Resolution |
|------|-----|-------------|------------|---------------|------------|
| [date] | [gdd] | [old requirement text] | [new requirement text] | ADR-NNNN | [Superseded/Updated/Valid] |
Ask: "May I update the traceability index?"
9. Output Change Impact Document
Ask: "May I write the change impact report to docs/architecture/change-impact-[date]-[system-slug].md?"
The document contains:
- The change summary from step 3
- The full impact analysis from step 5
- Resolution decisions made in step 7
- List of ADRs that need to be written or updated
If user approved: Verdict: COMPLETE — change impact report saved.
If user declined: Verdict: BLOCKED — user declined write.
10. Follow-Up Actions
Based on the resolution decisions, suggest:
- ADRs marked Superseded: "Run
/architecture-decision [title] to write the
replacement ADR. Then re-run /propagate-design-change to verify coverage."
- ADRs to update in place: List the specific fields to update in each ADR
- If many ADRs affected: "Run
/architecture-review after all ADRs are updated
to verify the full traceability matrix is still coherent."
Collaborative Protocol
- Read silently — compute the full impact before presenting anything
- Show the full report first — let the user see the scope before asking for action
- Ask per-ADR — don't batch decisions; each affected ADR may need different treatment
- Ask before writing — always confirm before modifying any file
- Non-destructive — never delete ADR content; only add "Superseded by" notes