docs(notes): archive low-value decision records

.agents/notes/README.md

@@ -11,12 +11,12 @@ Every Agent Note has two axes, both encoded in its **path** — `{lifecycle}/{cl
 - **Lifecycle** (the top-level folder) is the Agent Note's status, and an Agent Note moves between folders as that status changes:
   - **`proposed/`** — proposals reviewed before implementation; not yet built (or only partly).
   - **`implemented/`** — the decision shipped. The file records what was decided and what was rejected, and is **kept current with what actually shipped**: when the code later moves a file, renames a package, or changes a key/default, the Agent Note is updated in the same change to match (facts only — paths, names, structure — not the decision itself). See [implemented/AGENTS.md](implemented/AGENTS.md).
-  - **`rejected/`** — the proposal was considered and declined. Kept for the record so the rejection isn't re-litigated.
+  - **`rejected/`** — the proposal was considered and declined. Keep it only while its rationale prevents a tempting, meaningful mistake; otherwise delete the complete triplet.
 - **Class** (the nested folder) is the *kind* of decision — see [Classification](#classification) below.
 
 The date in the filename is when the topic was **first proposed** (per git history). Cross-references between Agent Notes use relative markdown links (`[topic](../../implemented/architecture/2026-…-….md)`) — never bare prose or numbers — so they are mechanically checkable and survive moves between folders.
 
-The tree is the inventory: browse its lifecycle/class folders or search the repository. Do not add a centralized `INDEX.md`; the [no-index Agent Note](implemented/process/2026-07-19-remove-generated-agent-note-index.md) owns the rationale.
+The active lifecycle tree is the working inventory: browse its lifecycle/class folders or search the repository. Do not add a centralized `INDEX.md`; the [no-index Agent Note](implemented/process/2026-07-19-remove-generated-agent-note-index.md) owns the rationale. Low-future-value implemented records move to the separate frozen [`archived/`](archived/AGENTS.md) tree described below.
 
 ## Classification
 
@@ -33,6 +33,14 @@ Each Agent Note belongs to one path-encoded class from the closed set in `script
 
 The `architecture` / `process` line: **architecture** is about the source we ship; **process** is the surrounding tooling and workflow. (`refactor` is deliberately absent — it overlaps `simplification`, whose discriminator, "does observable behavior change?", already covers it.)
 
+## Archiving and deletion
+
+Archive an implemented Agent Note when the shipped decision is complete and its rationale is unlikely to guide future work. Keep it active when its alternatives, ownership boundary, negative guarantee, durable or wire semantics, security rule, or reintroduction condition remains useful. Never archive a proposed note: reject an obsolete proposal. Keep a rejected note only while it prevents a plausible mistake; otherwise delete its English, Chinese, and sidecar files together. Use the calibrated [`dsh-archive-agent-notes`](../skills/dsh-archive-agent-notes/SKILL.md) workflow rather than word count, age, or a target quota.
+
+The archive is path-encoded as `archived/{class}/yyyy-mm-dd-topic-title.md`; `implemented` is deliberately absent because only implemented notes can enter it. An archival change moves the complete English/Chinese/sidecar triplet, retains `Status: implemented`, inserts the same `Archived: YYYY-MM-DD` line immediately below that status in both language files, re-records the sidecar, and repairs or deletes inbound links. These are the only permitted content changes during archival.
+
+Once sealed, every archived triplet is permanently frozen. Do not edit, translate, reformat, update, move, or delete it, and do not treat it as authority for current behavior. Documentation gates skip archived sources, including their outbound links; active prose may still link into an archived note when it intentionally cites history. [`verify-archived-agent-notes`](../../scripts/verify-archived-agent-notes.ts) enforces the closed class tree, complete triplets, archive metadata, sidecar hashes, and the append-only frozen-content manifest. The [archive-policy Agent Note](implemented/process/2026-07-26-frozen-agent-note-archive.md) owns the rationale.
+
 ## When to write one
 
 Every non-trivial change MUST add or update at least one Agent Note in the same PR. A change is non-trivial when it alters behavior, architecture, a cross-file or cross-package contract, process or tooling, testing strategy, an on-disk, wire, or configuration format, or another decision a maintainer may reasonably revisit. A proposal for substantial future work starts in `proposed/`; a decision already made starts in `implemented/`. Pick the class folder that matches the decision (see [Classification](#classification)).
@@ -45,7 +53,7 @@ A feature-addition note may be consolidated into the later removal note only whe
 
 ## The file format
 
-Every Agent Note follows one in-file format, enforced by `pnpm run verify-agent-note-format` ([scripts/verify-agent-note-format.ts](../../scripts/verify-agent-note-format.ts), part of `doc-sync`); the rationale for the format — and the alternatives it rejected — is [the uniform-format Agent Note](implemented/process/2026-07-05-uniform-agent-note-format.md).
+Every active Agent Note follows one in-file format, enforced by `pnpm run verify-agent-note-format` ([scripts/verify-agent-note-format.ts](../../scripts/verify-agent-note-format.ts), part of `doc-sync`); the rationale for the format — and the alternatives it rejected — is [the uniform-format Agent Note](implemented/process/2026-07-05-uniform-agent-note-format.md). Archived notes retain the format they had when sealed plus the archive-date line above.
 
 ### The header block