61 added, 18 removed. Audit A to A.
---
name: codebase-recon
description: 'Reconstruct a repository as cited entry-to-test flows and bounded claims. Triggers: "codebase recon", "trace this codebase", "repository audit", "refresh the prior recon".'
practices:
- legacy-code-seams
- ddd-bounded-context
- design-by-contract
hexagonal_role: supporting
consumes:
- repo-context
- existing-docs
produces:
- codebase-recon.v1
- evidence-bounded-recon-report
context_rel:
- kind: customer-of
with: research
- kind: customer-of
with: validate
- kind: customer-of
with: doc
skill_api_version: 1
user-invocable: true
context:
window: fork
intent:
mode: task
sections:
exclude:
- HISTORY
intel_scope: topic
metadata:
capabilities: [codebase_recon]
effects: [write_recon_pack]
canonical_status: canonical
disposition: keep_specialist
tier: execution
dependencies: []
output_contract: codebase-recon.v1 JSON validated by skills/codebase-recon/scripts/validate-output.sh with a companion cited report
---
# Codebase Recon
Build a reusable, falsifiable model of a repository. This skill reports what
the tree and executable probes support; it does not edit code or issue a final
PASS/WARN/FAIL verdict.
## Constraints
- To prevent a floating recon, record the exact repository commit and local
source-of-truth precedence.
- Because confidence is not evidence, type every material claim and cite each
fact and inference.
- To preserve traceability, prefer a verified delta when a prior pack exists
instead of rewriting unchanged evidence as fresh discovery.
## Modes, views, and lenses
One skill replaces a cluster of loose recon skills. Steer it with mode, view
emphasis, lens, and depth — do not invent a second skill for each shape.
| Control | Values | Use when |
|---|---|---|
| **Mode** | `baseline` \| `delta` | First pack vs refresh after a prior recon |
| **View emphasis** | mental model · bounded audit · pattern evidence · synthesis | Archaeology-style map, audit-style findings, pattern harvest, or executive synthesis |
| **Lens** | persistence · auth · CLI · build · test (one per pass) | Domain-deep cut instead of a shallow whole-tree sweep |
| **Depth** | quick · standard · deep | Orientation vs onboarding vs decision-grade evidence |
Ask for the shape explicitly, for example:
```text
codebase-recon --mode=delta --view=audit --lens=cli --depth=standard
codebase-recon baseline, mental-model view, persistence lens, deep
```
Natural-language equivalents count. The durable pack still carries all four
views; emphasis changes what you spend tokens on and what the companion report
leads with. Pattern packaging beyond evidence pointers belongs in
[`pattern-mining`](../pattern-mining/SKILL.md). Binding PASS/FAIL stays with
[`validate`](../validate/SKILL.md).
## Workflow
1. Record the current commit and the repository's local source-of-truth
- precedence. Search for a prior recon pack before starting.
+ precedence. Search for validated prior manifests before starting with
+ `skills/codebase-recon/scripts/validate-output.sh --repo-root <target> --discover-priors`.
+ Successful empty output means no prior pack exists at either documented
+ default.
2. If no prior pack exists, use `baseline` mode. If one exists, verify its
still-valid claims against the current commit and use `delta` mode. Preserve
valid evidence by reference and describe only changed paths and synthesis.
3. Trace representative paths from entry point to domain logic, integration
boundary, and test. Prefer a few complete flows over a broad file inventory.
4. Keep four views distinct in the report: mental model, bounded audit, pattern
evidence, and synthesis. Label each claim `fact`, `inference`, or `unknown`,
assign confidence, and cite evidence for facts and inferences.
5. List inspected and uninspected scope. Write the JSON manifest and companion
report, then run the validator. Missing evidence and hidden coverage gaps are
contract failures, not prose caveats.
## Docs-first entry-point tracing
Enter through what the repository declares about itself — README, architecture
docs, build manifests, CLI help — and only then verify those declarations
against the tree. Before the first broad search, list the declared entry points
and trace at least one of them to code. The named failure mode is grep-first
drift: opening with keyword sweeps builds a model of whatever happened to
match, and the recon inherits the search terms' blind spots instead of the
repository's actual shape. When declaration and code disagree, that is a
finding, not noise: record the doc's claim as `inference`, the traced behavior
as `fact`, and cite both.
## One-domain-deep lens per pass
Each pass adopts exactly one lens — persistence, auth, CLI surface, build
system, test harness — and follows it from entry point through domain logic to
its tests before switching lenses. A pass ends in exactly one of two states:
the lens has one complete entry-to-test flow, or the report names the file and
line where the trace was cut and why. The named failure mode is the shallow
sweep: touching every directory at depth one produces a file inventory that
reads like a model but supports no claim, because no path was followed far
enough to falsify anything.
## Citation floor: file:line or downgrade
The durable output doc earns its keep only if a future reader can re-verify a
claim without redoing the recon. Every `fact` cites file:line; every
`inference` cites the file:line facts it rests on. A claim that cannot be
cited is downgraded to `unknown` before the report ships — never shipped
- uncited at its original confidence. The manifest validator accepts a bare file
- path (it requires the path resolve to an existing regular file, so a bare
- directory is rejected as a coverage gap), but does not require the line number;
- hold the companion report to the stricter floor: a path without a line is a
- pointer to homework, not a citation, and counts as a coverage gap in the
- report's own terms.
+ uncited at its original confidence. The manifest validator checks citations
+ against the exact Git commit declared by that manifest. They must be safe
+ repository-relative regular-file paths; artifact-local and external paths are
+ rejected because this schema has no digest field for those bytes. A supplied
+ line number must exist in the committed blob. The validator also resolves each
+ representative flow path at that commit. It does not require every citation to
+ carry a line number; hold the companion report to the stricter floor: a path
+ without a line is a pointer to homework, not a citation, and counts as a
+ coverage gap in the report's own terms.
When reconstructing a repository other than the one that ships this skill, pass
`--repo-root <target>` to the validator so evidence resolves against the target
tree rather than the skill's own checkout.
## Output Specification
- **Artifact directory:** the caller-selected output path, defaulting to `.agents/scratch/codebase-recon/<run-id>/`
- **Filename convention:** `codebase-recon.json` with companion report
`codebase-recon.md` in the same directory.
- **Format:** `codebase-recon.v1` JSON manifest plus an evidence-cited Markdown
report covering the same commit, mode, flows, claims, and scope boundaries.
+ The manifest's `report` object names `codebase-recon.md` and binds its
+ lowercase SHA-256. The report carries one
+ `<!-- codebase-recon-report.v1 -->` marker plus `manifest_commit`,
+ `manifest_mode`, `flows_sha256`, `claims_sha256`, and `coverage_sha256`
+ markers computed from canonical compact sorted JSON for those sections.
- **Validation command:** `skills/codebase-recon/scripts/validate-output.sh <codebase-recon.json>`
- validates the machine-readable manifest; the cited Markdown report remains
- its human-readable companion.
+ snapshots and validates both artifacts, then rechecks their identities and
+ the repository HEAD/index/worktree before returning.
- **Downstream handoff:** pass both validated artifact paths to the requesting
research, planning, review, or documentation workflow; the consumer owns any
decision or code-change plan.
- Baseline manifests carry at least one complete entry-to-test flow. Delta
- manifests name an existing prior recon, prove `baseline_verified: true`, and
- describe at least one changed path. Every manifest lists both inspected and
- uninspected scope.
+ ### Earlier default compatibility
+ Packs already stored under `.agents/recon/<run-id>/` remain in place. The
+ validator's `--discover-priors` mode enumerates validated
+ `codebase-recon.json` manifests under both that legacy root and the current
+ scratch root. Record the selected manifest's exact path in `prior_recon`; delta
+ validation re-validates the cited manifest and its prior chain instead of
+ accepting a path merely because it exists. New packs use the current default
+ unless the caller supplies a different path. Never move, copy, or delete an
+ earlier pack merely to make its directory match the new state tier, because
+ that would obscure the identity a delta cites. Downstream consumers use the
+ exact returned artifact paths rather than scanning only one default root. An
+ earlier pack without a digest-bound companion report remains untouched but is
+ not returned as validated prior evidence under the current contract.
+
+ Baseline manifests carry at least one complete entry-to-test flow. A manifest
+ being handed off must name the target repository's current `HEAD` by its full
+ object-format OID; abbreviations and hex-looking refs are rejected. Historical
+ manifests cited as priors must likewise carry full immutable commit OIDs that
+ resolve in that repository.
+ Delta manifests name an existing prior recon, set `baseline_verified: true`,
+ and list exactly the paths in Git's prior-commit-to-current-commit diff. The
+ validator derives those facts rather than trusting the boolean or path list.
+ It also refuses dirty tracked, staged, or untracked source state outside
+ `.agents/`, because those bytes are not bound by the declared commit. Every
+ manifest lists both inspected and uninspected scope. Manifests and companions
+ must be real regular files, are read from one snapshot, and are rechecked along
+ with HEAD and source status after validation so a mid-run swap cannot earn a
+ green result for different bytes.
+
The validator is the machine boundary:
```bash
skills/codebase-recon/scripts/validate-output.sh <recon.json>
```
- Evidence entries are existing file paths, optionally followed by a line number.
- Delta manifests require an existing prior pack, `baseline_verified: true`, and
- at least one described change.
+ Evidence entries are repository-relative files at the manifest's commit,
+ optionally followed by a line number.
+ Delta manifests require a valid prior `codebase-recon.json` chain, an ancestor
+ commit, `baseline_verified: true`, and an exact changed-path match to the Git
+ diff ending at current `HEAD`. Enumerate validated manifests at both documented
+ defaults with:
+ ```bash
+ skills/codebase-recon/scripts/validate-output.sh --repo-root <target> --discover-priors
+ ```
+
Executable behavior:
[references/codebase-recon.feature](references/codebase-recon.feature).
## Quality
- - Every fact and inference resolves to existing evidence; unknowns remain
- visibly typed and never masquerade as established behavior.
+ - Every fact and inference resolves to evidence in the manifest's exact commit;
+ unknowns remain visibly typed and never masquerade as established behavior.
- Representative flows reach entry, domain, integration, and test surfaces,
while inspected and uninspected scope stay explicit.
- The named validator passes before the JSON manifest and companion report are
handed to a downstream consumer.
## Do not
- Regenerate a full replacement report when a verified delta is possible.
- Present an inference as fact or omit uninspected scope.
- Turn the recon artifact into a completion verdict or a code-change plan.