atlas-rescout

name	atlas-rescout
description	Incremental delta re-scout (Phase A/T mode) — a READ-ONLY, evidence-anchored re-run that reuses a prior scout-report + its Memex store + a git-diff range to re-probe ONLY the changed surface, carrying unchanged findings forward verbatim. Narrows (does NOT close) the always-on-live-index staleness gap. Use at Phase A intake when a prior scout-report.md + Memex store exist for the same surface and the question is "what changed since the last scout" or "re-verify the prior map against HEAD". Do NOT use for a first-time scout (run the full A→T→L→A→S cycle instead).
allowed-tools	search_symbol graph_query search_text view_file memex_read
metadata	{"methodology":"ATLAS","phase":"A"}

SKILL: Delta re-scout (incremental mode)

When to use

Load when: a prior scout-report.md + its Memex excerpt store exist for this surface, and you need to re-establish currency against a newer commit without re-running the full mission.

Unload when: the delta-scout-report is emitted with every prior finding re-labelled FRESH / UNCHANGED / RE-VERIFIED / NEWLY-STALE.

Honest scope (read this first). This is a faster evidence-anchored re-run, not an always-on live index. ATLAS-as-a-separate-step is intrinsic to its read-only-by-construction design; a true always-on index is an atlas-aci runtime / nexus integration concern. The delta re-scout narrows the staleness penalty by re-probing only changed surfaces — it does not close the live-index gap. Do not over-claim it.

This mode is read-only (I-1). It reads git diff / git log via the existing deterministic Traverse ladder (rg / git log in skills/traverse.md), never a write tool. Memory recall and Memex reads are permitted under I-1.

---

Contract

Field	Value
LLM calls permitted	At the synthesis edge only; the changed-surface computation is deterministic.
Tool budget	Bounded by the changed-surface size, not the full repo — this is the whole point.
Output	delta-scout-report.md — same class as scout-report.md, with a section-3 finding-status label per finding.

---

Inputs

1. Prior scout-report.md (surfaced by mcp__crystalium__recall at Phase A intake, or supplied by the parent) — its FINDING-XXX records with path:line anchors and the originating commit.
2. Prior Memex store — the byte-exact excerpts those findings cited.
3. A git-diff range — <prior_mission_commit>..HEAD (the prior commit is recorded in the prior scout-report telemetry; if absent, fall back to the prior report's git heatmap base).

---

Procedure

Step 1 — Compute the changed surface (deterministic)

git diff --name-only <prior_mission_commit>..HEAD

Intersect the changed file set with the prior map.md MAP-MODULES:

CHANGED-SURFACE = diff_files ∩ prior MAP-MODULES (and their MAP-GRAPH neighbours)

Files that changed but lie outside the prior scope are noted in MAP-GAPS (they may warrant a full scout, not a delta) but are not re-probed here.

Step 2 — Re-run Phase T over the changed surface ONLY

Re-map structure (entrypoints, modules, call-graph edges) only for CHANGED-SURFACE. Deterministic and cheap — Tree-sitter / rg / git log, no LLM calls (Phase T rule). Unchanged regions reuse the prior map.md slice verbatim.

Step 3 — Mark prior findings STALE by anchor intersection

A prior FINDING-XXX is STALE iff its anchored path:line_start-line_end range intersects a changed hunk in the diff. Findings whose anchors are untouched are not re-probed.

Step 4 — Re-probe ONLY the stale findings

For each STALE finding, run the skills/locate.md Tier 1–5 probe ladder over its anchor, producing an updated finding (new anchor, new confidence). This is the only LLM-synthesis-edge work in the mode.

Step 5 — Carry forward UNCHANGED findings verbatim

Findings whose anchors were untouched are copied verbatim from Memex — claim, anchor, confidence, and excerpt_ref unchanged. Provenance is preserved; this is ATLAS's differentiator (read-only + evidence-anchored + auditable lineage). Do not re-author what did not change.

---

Output — delta-scout-report.md

Same class and section layout as scout-report.md (reuse the existing templates/scout-report.md and schemas/scout-report.v1.json). Section 3 of the delta report labels every finding with its delta status:

Label	Meaning
FRESH	New finding, no prior counterpart (surfaced by the changed surface).
UNCHANGED	Carried forward verbatim from Memex; anchor untouched by the diff.
RE-VERIFIED	Prior finding whose anchor was touched, re-probed, claim still holds (possibly new line range).
NEWLY-STALE	Prior finding whose anchor was touched and the claim no longer holds; superseded or dropped to a GAP.

Each label records the originating commit (the prior commit for UNCHANGED/carried-forward, HEAD for FRESH/RE-VERIFIED) so the lineage is auditable.

---

Stop condition

The delta re-scout completes when every prior finding has a delta label and every changed-surface region has either a FRESH finding or a GAP. No re-scatter beyond agent.md P0 rule 9 (max recursion = 1).

---

Telemetry

delta-rescout | changed_files: <n> | stale_findings: <n> | unchanged_carried: <n>
              | fresh: <n> | reverified: <n> | newly_stale: <n>
              | reprobe_tool_calls: <n vs full-scout estimate>

The reprobe_tool_calls vs full-scout estimate ratio is the staleness-saving signal — it quantifies how much of the live-index gap the delta narrowed.

---

Exit gate

• Changed surface computed deterministically (git diff ∩ prior MAP-MODULES).
• Phase T re-ran over the changed surface ONLY; unchanged map reused verbatim.
• Every prior finding labelled FRESH / UNCHANGED / RE-VERIFIED / NEWLY-STALE with an originating commit.
• UNCHANGED findings carried verbatim from Memex (provenance preserved).
• Changed-surface files outside prior scope noted in MAP-GAPS, not silently dropped.
• Report does NOT claim to be an always-on index — staleness narrowed, not closed.