Module projects 

The single owner of project behaviour (mission first-class-projects-01M3BYBW, WP02).

Everything about a project lives here: identity and resolution, the registry lifecycle (create / edit / delete / list), derived membership and the index that makes a project filter a bucket lookup, the association mutations, and missing-reference diagnosis. Surfaces call this rather than re-deriving, because a second identity resolver or a stored membership index is exactly the divergence the mission’s charter escalates (C-006, NFR-001).

What this module deliberately does not do

• It touches no files. It takes an in-memory Config and an in-memory issue set, and returns values. Storage owns the write; this module owns the rule. The whole surface is therefore testable with no Store and no tempfile (T010 step 4).
• It does not know about the issue model. ProjectNode is the minimum an issue must expose — its number, title, status, and its projects id list — and WP03 implements it for crate::model::Issue in src/model.rs (this mission’s WP03 owns that file), exactly as the hierarchy service’s HierarchyNode is implemented there. WP02 is forbidden from touching src/model.rs, so the service is defined against the shape WP03 provides.
• It never mutates or returns a whole Issue. associate and dissociate return a ProjectChange: the resulting association list plus the History event to append. Storage applies it. That is the boundary that keeps this module model-free.
• It stores no membership. A project’s members are derived by inverting the issues’ association lists, never persisted (data-model §4, C-003).
• It does not compute progress or health. ProjectProgress and ProjectHealth are WP04’s, added to this module additively; the single health operation the contract names lands there (contract §2).

The index is built once per read

ProjectIndex is the derived view over one snapshot. It is built once (ProjectIndex::build) and every read — ProjectIndex::membership, ProjectIndex::resolve, ProjectIndex::missing — reads that one value rather than rebuilding. The contract’s free operations each build exactly one index per call, so a filter is a bucket lookup rather than a scan (NFR-001).

Ordering is deterministic

Members are ordered by issue number, projects by declaration order, and missing references by (issue number, project id), so repeated reads of the same snapshot are identical (contract §6).

Structs

BulkProjectOutcome

The per-issue outcome of a bulk association (contract §1).

IssueKey

A project issue number, as the derived structures key it.

MemberRef

One member of a project, with its derived display label.

MissingProjectReference

A stored association whose project is not in the registry (data-model §3).

NewProject

The spec for a new project.

Project

The service-side view of a project (data-model §2).

ProjectChange

The outcome of an association mutation: the resulting list plus the event.

ProjectDeletion

The impact report of a project deletion (contract §1).

ProjectEdit

The fields of a project edit.

ProjectEvent

One association mutation, ready for storage to append to ## History.

ProjectHealth

A project’s health counters (data-model §5, FR-003).

ProjectHealthReport

The typed value the health operation returns (contract §1).

ProjectIndex

The derived project view over one snapshot of issues and the registry.

ProjectMembership

The derived members of a project (data-model §4).

ProjectProgress

A project’s completion progress (data-model §5, FR-003).

Enums

Patch

One field edit: leave it, clear it, or set it.

ProjectDiagnosticKind

The diagnostic kinds contracts/project-service.md §1 names, spelled exactly.

ProjectError

Why a project operation was refused.

ProjectEventKind

The two association mutations, as the ## History section records them.

Constants

MISSING_REFERENCE_KIND

The lint diagnostic kind for an association that no longer resolves.

MULTIPLE_PROJECTS_BUCKET

The single bucket for an issue in several projects.

NO_PROJECT_BUCKET

The clearly labelled bucket for an issue in no project.

PROJECTS_KEY

The frontmatter key carrying an issue’s project associations.

Traits

HealthNode

The one per-issue fact project health reads beyond ProjectNode.

ProjectNode

The minimum an issue must expose for project derivation.

Functions

assigned_keys

The members of a snapshot that carry an assignee.

associate

Associate an issue with a project, producing the change and its History event.

association_detail

The single wording for an association change’s ## History detail line.

bulk_associate

Associate each selector independently, reporting every outcome.

create_project

Create a project, allocating a fresh stable id (FR-001).

delete_project

Remove a project from the registry, reporting the issues that reference it.

dissociate

Remove an issue’s association with a project.

duplicate_name_reason

The single wording for a project name refusal.

edit_project

Edit a project’s fields by reference.

health

Progress and health for a project, in one index build (contract §1).

invalid_dates_reason

The single wording for a project date refusal.

list_projects

The projects in declaration order, with derived member counts.

membership

The ordered membership of a project, by id or name.

membership_index

Build the reverse index once for one read (HashMap<ProjectId, Vec<IssueKey>>).

missing_reference_reason

The single wording for an association that no longer resolves.

project_bucket_label

The group-section label for one issue’s resolved project memberships.

project_display

The shared display form for a project: Platform hardening (p-3f9a2c).

resolve

Resolve a project by id (first) or by name.

resolve_project_id

Resolve a project id from a reference: id first, then a name convenience.

unknown_issue_reason

The single wording for an issue selector that names no issue.

unknown_project_reason

The single wording for an unresolvable project reference.

validate_references

Every association in the snapshot whose project is not in the registry.