feat(#1561): assumption-delta advisory checkpoint (#1767)

* feat(#1561): assumption-delta advisory checkpoint

* chore(#1561): backfill changeset PR number (#1767)

---------

Co-authored-by: review-bot <review-bot@gsd>

docs/CONFIGURATION.md

@@ -286,6 +286,7 @@ All workflow toggles follow the **absent = enabled** pattern. If a key is missin
 | `workflow.nyquist_validation` | boolean | `true` | Test coverage mapping during plan-phase research |
 | `workflow.ui_phase` | boolean | `true` | Generate UI design contracts for frontend phases |
 | `workflow.ui_safety_gate` | boolean | `true` | Prompt to run /gsd-ui-phase for frontend phases during plan-phase |
+| `workflow.assumption_delta` | boolean | `true` | Advisory architecture checkpoint during planning. When a phase makes something **plural, optional, or chosen** that used to be **singular, required, or derived** (e.g. a second auth method, a required field becoming optional, a constant becoming a parameter), the planner is prompted to re-ask whether the primary key / identity model still names the right thing (promote the new general representation vs. add it alongside). Non-blocking; fires only on a detected signal. Bare "or" is intentionally excluded (prose false-positives). Inspect a phase with `gsd query assumption-delta scan <phase>`. Added in #1561 |
 | `workflow.ui_review` | boolean | `true` | Run visual quality audit (`/gsd-ui-review`) after phase execution in autonomous mode. When `false`, the UI audit step is skipped. |
 | `workflow.node_repair` | boolean | `true` | Autonomous task repair on verification failure |
 | `workflow.node_repair_budget` | number | `2` | Max repair attempts per failed task |

docs/INVENTORY-MANIFEST.json

@@ -283,6 +283,7 @@
       "agent-command-router.cjs",
       "agent-install-check.cjs",
       "artifacts.cjs",
+      "assumption-delta.cjs",
       "audit-command-router.cjs",
       "audit.cjs",
       "capability-activation.cjs",

docs/reference/capability-matrix.md

@@ -44,7 +44,7 @@ Core package and are stamped with the package version at release (per
 ADR-1244 D6). They are not subject to the consent or integrity-pin flow applied
 to third-party capabilities.
 
-### Feature capabilities (role: feature) — 16
+### Feature capabilities (role: feature) — 17
 
 Feature capabilities extend what the loop does — contributing research,
 planning, execution, verification, or ship artefacts at the loop extension
@@ -53,6 +53,7 @@ points.
 | id | role | tier | engines.gsd | extension points | hook kinds | source |
 |---|---|---|---|---|---|---|
 | `ai-integration` | feature | full | `>=1.6.0` | `plan:pre` | step | first-party |
+| `assumption-delta` | feature | full | `>=1.6.0` | `plan:pre` | contribution | first-party |
 | `audit` | feature | full | `>=1.6.0` | — | — | first-party |
 | `code-review` | feature | full | `>=1.6.0` | `execute:post` | step | first-party |
 | `drift` | feature | full | `>=1.6.0` | `plan:pre`, `execute:wave:post` | gate | first-party |