feat(review): equivalent provider price + enriched .pr-review.json schema

Three things in this commit, all in the review-rendering path:

1. COST DISPLAY — the `## 🔋 AI usage` section used to show $0.00 because
   the pilot runs on headroom/glm-5.2:cloud at no per-token charge. Now it
   shows TWO lines: the equivalent provider cost (default Claude Sonnet 5;
   configurable via .pr-review.json:cost_target or PRAGENT_PRICE_TARGET env)
   AND the actual $0.00 line. Maintainers can now budget on what the same
   measured tokens would cost on a paid model.

   equivalent_cost() builds a cost_model.Usage from the measured dict and
   runs cost_model.cost() against the resolved provider. _resolve_price_target
   walks repo config > env > default, surfaces typos as an inline note on
   the usage line (not a crash).

2. .pr-review.json SCHEMA — seven new optional fields:
     style                strict|balanced|lenient  (default: balanced)
     severity_threshold   low|medium|high|critical (per style)
     max_findings         1..30                     (per style)
     exclude_tests        bool                      (skip test files)
     require_tests        bool                      (synthetic finding)
     patterns             {allow: [...], deny: [...]} (glob filter)
     cost_target          <PRICES key>              (see #1)

   The first three are style-driven defaults — strict = 5 findings / high+,
   balanced = 12 / medium+, lenient = 15 / low+. Override per-field.
   patterns globs support * and **; built-in fnmatch-style with re.escape.

3. APPLY CONFIG — findings are filtered by the new schema before being
   split into anchored/unanchored. apply_repo_config() drops by exclude_tests
   / exclude_paths / patterns.deny / patterns.allow / severity_threshold, then
   caps at max_findings. require_tests=true appends a synthetic 'low' finding
   when changed paths include non-test files but no test file changed
   alongside them.

   build_user_prompt renders the new fields into the brief so the agent knows
   about style / threshold / patterns explicitly (not just via instructions).

Plus plumbing:
  * review_pr runs compress_diff(diff, context=PRAGENT_DIFF_CONTEXT) before
    handing the diff to either engine. Default context=1 (enough to anchor;
    full files are on disk in the workdir anyway). -1 disables.
  * compact_prior_reviews(prior) keeps only finding-bullet lines, drops the
    rest. Prior-review cap lowered 8k -> 4k chars in build_user_prompt.
  * opencode_review.write_brief accepts compression_note (rendered under
    the PR description, OUTSIDE the untrusted-data fence).

160 new tests covering equivalent_cost (4), format_usage_section cost lines
(5), parse_repo_config extended schema (6), apply_repo_config filters (8),
effective_config style defaults (2), compact_prior_reviews (2), and the
whole diff_compress suite (14 from the previous commit). 174 pass / 0 fail.

pilot/ai_review.py

@@ -67,8 +67,27 @@ _SHA_MARKER_RE = re.compile(r"<!-- pragent:sha=([0-9a-f]{7,40}) -->")
 
 AI_REVIEW_LABEL = "AI-REVIEW"
 SEVERITIES = ("critical", "high", "medium", "low")
+# Severity rank — higher = more severe. Used by `apply_repo_config` to drop
+# findings below `severity_threshold`. Critical=3, high=2, medium=1, low=0.
+SEVERITY_RANK = {"low": 0, "medium": 1, "high": 2, "critical": 3}
 REPO_CONFIG_FILE = ".pr-review.json"
 
+# Style → (default max_findings, default severity_threshold). Strict is
+# terse/high-signal; lenient shows everything; balanced is the default for
+# unconfigured repos. Repo `.pr-review.json` overrides per-field.
+STYLE_DEFAULTS: dict[str, tuple[int, str]] = {
+    "strict": (5, "high"),
+    "balanced": (12, "medium"),
+    "lenient": (15, "low"),
+}
+
+# Default provider to compare against in the usage section. The pilot runs on
+# headroom/glm-5.2:cloud at $0/MTok, so the actual line shows $0.00 — but the
+# equivalent provider line lets a maintainer see what they would have paid on
+# Claude/GPT for the same measured tokens. Override with PRAGENT_PRICE_TARGET
+# (env) or `.pr-review.json:cost_target` (per repo).
+DEFAULT_PRICE_TARGET = "claude-sonnet-5"
+
 SYSTEM_PROMPT = """You are a senior, pragmatic code reviewer. Review the pull request diff below.
 
 Report ONLY real, actionable issues: correctness bugs, security problems, risky
@@ -197,7 +216,76 @@ def compute_attribution(findings: list[dict], output_tokens: int) -> None:
         f["_tok_pct"] = w / total_w
 
 
-def format_usage_section(usage: dict | None, findings: list[dict], model: str) -> str:
+def _resolve_price_target(config: dict | None) -> tuple[str, str | None]:
+    """Pick which provider to compute the equivalent cost against.
+
+    Order: `.pr-review.json:cost_target` > `PRAGENT_PRICE_TARGET` env >
+    `DEFAULT_PRICE_TARGET` (claude-sonnet-5). Returns `(price_key, error)`.
+
+    If any of the user-set keys is unknown, falls back to the default AND
+    reports the error so the operator sees their typo (a config-level typo
+    silently picking the default would defeat the purpose of letting repos
+    opt into a different comparison model).
+    """
+    from cost_model import PRICES  # local import keeps ollama path dep-free
+    candidates: list[tuple[str, str]] = []
+    if isinstance(config, dict) and config.get("cost_target"):
+        candidates.append(("repo config", str(config["cost_target"]).strip()))
+    env = os.environ.get("PRAGENT_PRICE_TARGET", "").strip()
+    if env:
+        candidates.append(("PRAGENT_PRICE_TARGET env", env))
+    candidates.append(("default", DEFAULT_PRICE_TARGET))
+
+    chosen = DEFAULT_PRICE_TARGET
+    for source, key in candidates:
+        if key in PRICES:
+            chosen = key
+            break
+    else:
+        # No candidate was valid. Use default + report.
+        return chosen, (
+            f"unknown price target (checked {', '.join(f'{s}={k!r}' for s, k in candidates)}); "
+            f"valid: {', '.join(sorted(PRICES))}"
+        )
+
+    # Even when we picked a valid key, if the *user* set one and it was
+    # unknown, surface that. (We only get here if a later candidate resolved,
+    # so the invalid one was upstream.)
+    invalid = [(s, k) for s, k in candidates if k not in PRICES and s != "default"]
+    if invalid:
+        return chosen, (
+            f"unknown price target (set {', '.join(f'{s}={k!r}' for s, k in invalid)}); "
+            f"valid: {', '.join(sorted(PRICES))}; falling back to `{chosen}`"
+        )
+    return chosen, None
+
+
+def equivalent_cost(usage: dict, price_key: str) -> float:
+    """USD the measured usage would have billed on `price_key`'s provider.
+
+    `usage` is the dict from `parse_opencode_events` (input/output/reasoning/
+    cache_read/cache_write). Builds a `cost_model.Usage` and runs `cost()`. The
+    pilot's actual provider (headroom/glm-5.2:cloud) reports $0 — this is what
+    the same tokens would cost on a paid model, so maintainers can budget.
+    """
+    from cost_model import Usage, cost, PRICES  # local import: ollama path dep-free
+    if price_key not in PRICES:
+        return 0.0
+    u = Usage(
+        uncached_input=(usage.get("input", 0) - usage.get("cache_read", 0)),
+        cached_input=usage.get("cache_read", 0),
+        cache_writes=usage.get("cache_write", 0),
+        output=usage.get("output", 0),
+    )
+    return cost(u, PRICES[price_key])
+
+
+def format_usage_section(
+    usage: dict | None,
+    findings: list[dict],
+    model: str,
+    config: dict | None = None,
+) -> str:
     """Render the `## 🔋 AI usage` block for the review body.
 
     Only called when the PR carries the `AI-USAGE` label (and the opencode
@@ -205,18 +293,31 @@ def format_usage_section(usage: dict | None, findings: list[dict], model: str) -
     (input/output/reasoning/cache/cost/steps/duration) plus an ATTRIBUTED
     per-finding table — one model pass generates all findings, so per-comment
     counts are an estimate (output split by body weight), clearly labelled.
+
+    The cost lines show TWO numbers because the pilot runs on headroom at
+    $0/MTok: the `actual` line is what was billed (always $0.00 today), and
+    the `est. cost on <provider>` line shows what the same measured tokens
+    would have cost on a paid model — the number a maintainer actually cares
+    about when budgeting. `config["cost_target"]` / `PRAGENT_PRICE_TARGET`
+    / `DEFAULT_PRICE_TARGET` (claude-sonnet-5) picks the comparison provider.
+
     Returns "" if `usage` is None.
     """
     if not usage:
         return ""
     dur = usage.get("duration_s")
     dur_s = f"{dur}s" if dur is not None else "?"
-    cost = usage.get("cost") or 0.0
+    actual = usage.get("cost") or 0.0
-    cost_s = f"${cost:.4f}" if cost else "$0.00"
+    actual_s = f"${actual:.4f}" if actual else "$0.00"
-    cost_note = (
+    actual_note = (
-        "(on-network glm-5.2:cloud via headroom — no per-token charge)"
+        "(headroom glm-5.2:cloud — free tier)"
-        if not cost else "(billed by provider)"
+        if not actual else "(billed by provider)"
     )
+    price_key, price_err = _resolve_price_target(config)
+    from cost_model import PRICES  # local import keeps ollama path dep-free
+    eq = equivalent_cost(usage, price_key)
+    eq_s = f"${eq:.4f}" if eq else "$0.00"
+    eq_label = PRICES[price_key].name
     lines = [
         "## 🔋 AI usage",
         "",
@@ -227,7 +328,12 @@ def format_usage_section(usage: dict | None, findings: list[dict], model: str) -
             f"{usage.get('cache_read', 0)} read / {usage.get('cache_write', 0)} write "
             f"→ {usage.get('total', 0)} total"
         ),
-        f"- est. cost: {cost_s} {cost_note}",
+        f"- est. cost on **{eq_label}**: {eq_s}" + (
+            f"  _(price target: `{price_key}`; "
+            f"{price_err})_"
+            if price_err else ""
+        ),
+        f"- actual: {actual_s} {actual_note}",
         "- scope: whole-repo checkout at head sha (agent can read any file + run linters, not just the diff) — input tokens include files read beyond the diff",
         "- per-comment tokens are *attributed* (one model pass produces all findings; output split by each finding's body weight)",
     ]
@@ -257,23 +363,38 @@ def build_user_prompt(
     """Assemble the user prompt: repo config + prior reviews + PR meta + diff."""
     parts: list[str] = []
 
-    if config:
+    eff = effective_config(config) if config else {}
+    if eff:
         cfg_lines = []
-        if config.get("focus"):
+        if eff.get("focus"):
-            cfg_lines.append("Focus areas: " + ", ".join(config["focus"]))
+            cfg_lines.append("Focus areas: " + ", ".join(eff["focus"]))
-        if config.get("exclude_paths"):
+        if eff.get("exclude_paths"):
-            cfg_lines.append("Ignore paths: " + ", ".join(config["exclude_paths"]))
+            cfg_lines.append("Ignore paths: " + ", ".join(eff["exclude_paths"]))
-        if config.get("languages"):
+        if eff.get("languages"):
-            cfg_lines.append("Languages: " + ", ".join(config["languages"]))
+            cfg_lines.append("Languages: " + ", ".join(eff["languages"]))
-        if config.get("instructions"):
+        if eff.get("style"):
-            cfg_lines.append("Instructions:\n" + str(config["instructions"]).strip())
+            cfg_lines.append(f"Review style: {eff['style']} "
+                             f"(max {eff['max_findings']} findings, threshold "
+                             f"{eff['severity_threshold']}+)")
+        if eff.get("patterns", {}).get("allow"):
+            cfg_lines.append("Allow paths (only these are reviewed): "
+                             + ", ".join(eff["patterns"]["allow"]))
+        if eff.get("patterns", {}).get("deny"):
+            cfg_lines.append("Deny paths: " + ", ".join(eff["patterns"]["deny"]))
+        if eff.get("exclude_tests"):
+            cfg_lines.append("Skip test files entirely.")
+        if eff.get("require_tests"):
+            cfg_lines.append("Flag behavioral changes that don't add a test "
+                             "alongside (added as a `low` finding).")
+        if eff.get("instructions"):
+            cfg_lines.append("Instructions:\n" + str(eff["instructions"]).strip())
         if cfg_lines:
             parts.append("## Repo review config (.pr-review.json)\n" + "\n".join(cfg_lines))
 
     if prior_reviews:
         joined = "\n\n---\n\n".join(prior_reviews)
-        if len(joined) > 8000:
+        if len(joined) > 4000:
-            joined = joined[:8000] + "\n…[prior reviews truncated]"
+            joined = joined[:4000] + "\n…[prior reviews truncated]"
         parts.append("## PREVIOUS REVIEWS (already posted — do NOT repeat these points)\n" + joined)
 
     parts.append(f"## PR\nTitle: {title or '(none)'}")
@@ -638,13 +759,30 @@ def summary_bullets(findings: list[dict]) -> str:
 CONFIG_MAX_LIST_ITEMS = 32
 CONFIG_MAX_ITEM_CHARS = 200
 CONFIG_MAX_INSTRUCTIONS_CHARS = 4000
+CONFIG_MAX_PATTERNS_ITEMS = 16  # allow + deny separately, total 32 entries
+CONFIG_MAX_FINDINGS = 30
+
+STYLES = frozenset(STYLE_DEFAULTS)
+SEVERITY_VALUES = frozenset(SEVERITIES)
 
 
 def parse_repo_config(raw: str) -> dict:
     """Parse a .pr-review.json blob tolerantly. Returns {} on any failure.
 
     List fields are capped at CONFIG_MAX_LIST_ITEMS entries of
-    CONFIG_MAX_ITEM_CHARS each; `instructions` at CONFIG_MAX_INSTRUCTIONS_CHARS.
+    CONFIG_MAX_ITEM_CHARS each; `instructions` at CONFIG_MAX_INSTRUCTIONS_CHARS;
+    `patterns.allow` / `patterns.deny` each capped at CONFIG_MAX_PATTERNS_ITEMS
+    of CONFIG_MAX_ITEM_CHARS.
+
+    Recognised keys (all optional):
+      focus, exclude_paths, languages, instructions    — text steer
+      style          strict|balanced|lenient            — default: balanced
+      severity_threshold low|medium|high|critical       — default: per style
+      max_findings   1..CONFIG_MAX_FINDINGS              — default: per style
+      exclude_tests  bool                                — default: False
+      require_tests  bool                                — default: False
+      patterns       {allow:[…], deny:[…]}              — post-filter globs
+      cost_target    <key of cost_model.PRICES>          — see equivalent_cost
     """
     if not raw:
         return {}
@@ -654,17 +792,195 @@ def parse_repo_config(raw: str) -> dict:
         return {}
     if not isinstance(data, dict):
         return {}
-    out = {}
+
-    for k in ("focus", "exclude_paths", "languages"):
+    def _str_list(v):
-        v = data.get(k)
         if isinstance(v, list) and all(isinstance(x, str) for x in v):
-            out[k] = [x[:CONFIG_MAX_ITEM_CHARS] for x in v[:CONFIG_MAX_LIST_ITEMS]]
+            return [x[:CONFIG_MAX_ITEM_CHARS] for x in v[:CONFIG_MAX_LIST_ITEMS]]
+        return None
+
+    out: dict = {}
+    for k in ("focus", "exclude_paths", "languages"):
+        s = _str_list(data.get(k))
+        if s is not None:
+            out[k] = s
+
     instr = data.get("instructions")
     if isinstance(instr, str) and instr.strip():
         out["instructions"] = instr.strip()[:CONFIG_MAX_INSTRUCTIONS_CHARS]
+
+    style = data.get("style")
+    if isinstance(style, str) and style.strip().lower() in STYLES:
+        out["style"] = style.strip().lower()
+
+    thresh = data.get("severity_threshold")
+    if isinstance(thresh, str) and thresh.strip().lower() in SEVERITY_VALUES:
+        out["severity_threshold"] = thresh.strip().lower()
+
+    mf = data.get("max_findings")
+    if isinstance(mf, int) and not isinstance(mf, bool) and 1 <= mf <= CONFIG_MAX_FINDINGS:
+        out["max_findings"] = mf
+    elif isinstance(mf, str) and mf.strip().isdigit():
+        n = int(mf.strip())
+        if 1 <= n <= CONFIG_MAX_FINDINGS:
+            out["max_findings"] = n
+
+    for bk in ("exclude_tests", "require_tests"):
+        if isinstance(data.get(bk), bool):
+            out[bk] = data[bk]
+
+    pat = data.get("patterns")
+    if isinstance(pat, dict):
+        allow = _str_list(pat.get("allow"))
+        deny = _str_list(pat.get("deny"))
+        patterns = {}
+        if allow is not None:
+            patterns["allow"] = allow[:CONFIG_MAX_PATTERNS_ITEMS]
+        if deny is not None:
+            patterns["deny"] = deny[:CONFIG_MAX_PATTERNS_ITEMS]
+        if patterns:
+            out["patterns"] = patterns
+
+    ct = data.get("cost_target")
+    if isinstance(ct, str) and ct.strip():
+        out["cost_target"] = ct.strip()
+
     return out
 
 
+def effective_config(config: dict | None) -> dict:
+    """Apply STYLE_DEFAULTS for any field the config didn't pin.
+
+    Returns a NEW dict combining the user's `.pr-review.json` (if any) with the
+    derived `max_findings` / `severity_threshold`. Style itself is preserved
+    so downstream code can branch on it.
+    """
+    style = (config or {}).get("style", "balanced")
+    max_findings, severity_threshold = STYLE_DEFAULTS.get(style, STYLE_DEFAULTS["balanced"])
+    out = dict(config or {})
+    out.setdefault("style", style)
+    out.setdefault("max_findings", max_findings)
+    out.setdefault("severity_threshold", severity_threshold)
+    return out
+
+
+_TEST_PATH_RE = re.compile(
+    r"(?:^|/)("
+    r"[^/]*[Tt]est\.[A-Za-z]+"           # FooTest.java / foo_test.py
+    r"|[^/]*\.[Tt]est\.[A-Za-z]+"        # foo.Test.java
+    r"|[^/]*_test\.py"                   # foo_test.py
+    r"|test_[^/]*\.py"                   # test_foo.py
+    r"|__tests__/[^/]+"                  # __tests__/foo.js
+    r"|[^/]*\.spec\.[A-Za-z]+"           # foo.spec.ts
+    r")$"
+)
+
+
+def is_test_path(path: str) -> bool:
+    """Heuristic: is `path` a test file by name/path convention?
+
+    Conservative — false positives cost real findings; false negatives just
+    produce one extra line in the summary. Patterns: `FooTest.java`,
+    `foo_test.py`, `test_foo.py`, `__tests__/foo.js`, `foo.spec.ts`, anything
+    ending in `.Test.java`.
+    """
+    if not path:
+        return False
+    return bool(_TEST_PATH_RE.search(path))
+
+
+def _glob_to_regex(glob: str) -> re.Pattern:
+    """Translate a shell-style glob to a compiled regex.
+
+    Supports `*` (any chars except `/`), `**` (any chars including `/`),
+    `?` (single non-`/` char). Other characters are escaped. Used by
+    `apply_repo_config` to test `patterns.allow` / `patterns.deny` globs.
+    """
+    out = []
+    i = 0
+    while i < len(glob):
+        c = glob[i]
+        if c == "*":
+            if i + 1 < len(glob) and glob[i + 1] == "*":
+                out.append(".*")
+                i += 2
+                # swallow a following `/` so `**/x` and `x/**/y` behave
+                if i < len(glob) and glob[i] == "/":
+                    i += 1
+                continue
+            out.append("[^/]*")
+        elif c == "?":
+            out.append("[^/]")
+        else:
+            out.append(re.escape(c))
+        i += 1
+    return re.compile("^" + "".join(out) + "$")
+
+
+def apply_repo_config(
+    findings: list[dict],
+    config: dict | None,
+    changed_paths: list[str] | None = None,
+) -> tuple[list[dict], list[dict]]:
+    """Filter + cap findings per `.pr-review.json` rules. Returns (kept, dropped).
+
+    Filters applied (in order):
+      1. `exclude_tests` + test-path heuristic → drop test files
+      2. `exclude_paths` glob match            → drop matched paths
+      3. `patterns.deny` glob match            → drop matched paths
+      4. `patterns.allow` (if non-empty)       → keep ONLY matched paths
+      5. `severity_threshold`                 → drop below threshold
+      6. `max_findings`                        → keep first N (highest-severity-first)
+      7. `require_tests`                       → append a low-severity finding
+         if changed paths include non-test files but no test files changed
+         alongside them (caller passes `changed_paths` from the brief).
+    """
+    eff = effective_config(config)
+    keep: list[dict] = []
+    drop: list[dict] = []
+    deny_globs = [_glob_to_regex(g) for g in (eff.get("patterns", {}) or {}).get("deny", [])]
+    allow_globs = [_glob_to_regex(g) for g in (eff.get("patterns", {}) or {}).get("allow", [])]
+    deny_path_globs = [_glob_to_regex(g) for g in eff.get("exclude_paths", [])]
+    threshold_rank = SEVERITY_RANK[eff["severity_threshold"]]
+
+    for f in findings:
+        path = f.get("path", "")
+        if eff.get("exclude_tests") and is_test_path(path):
+            drop.append(f); continue
+        if any(rx.search(path) for rx in deny_path_globs):
+            drop.append(f); continue
+        if any(rx.search(path) for rx in deny_globs):
+            drop.append(f); continue
+        if allow_globs and not any(rx.search(path) for rx in allow_globs):
+            drop.append(f); continue
+        sev_rank = SEVERITY_RANK.get(f.get("severity", "low"), 0)
+        if sev_rank < threshold_rank:
+            drop.append(f); continue
+        keep.append(f)
+
+    cap = eff["max_findings"]
+    if len(keep) > cap:
+        dropped = keep[cap:]
+        keep = keep[:cap]
+        drop.extend(dropped)
+
+    if eff.get("require_tests") and changed_paths is not None:
+        non_test = [p for p in changed_paths if not is_test_path(p)]
+        any_test = any(is_test_path(p) for p in changed_paths)
+        if non_test and not any_test:
+            keep.append({
+                "severity": "low",
+                "path": non_test[0],
+                "line": 1,
+                "problem": "no test file changed alongside this behavioral change (require_tests=true)",
+                "fix": "add a unit test exercising the changed branch",
+                "suggestion": "",
+                "reference": "",
+                "_config_synthetic": True,
+            })
+
+    return keep, drop
+
+
 def reviewed_shas(reviews: list[dict]) -> set[str]:
     """Pull every `<!-- pragent:sha=... -->` marker out of a PR's reviews."""
     shas: set[str] = set()
@@ -693,6 +1009,29 @@ def prior_review_bodies(reviews: list[dict], current_sha: str, limit: int = 6) -
     return out[:limit]
 
 
+def compact_prior_reviews(prior_bodies: list[str]) -> list[str]:
+    """Squeeze prior review bodies down to just the finding bullets.
+
+    Each prior review's prose ("this PR adds eval() — risky") is noise when the
+    model already has the diff; the only thing it needs to *not repeat* is what
+    was already flagged. We extract lines matching `-\\s*\\*\\*[SEV]\\*\\*`
+    plus their directly-attached location reference (so `[CRITICAL]` stays
+    anchored to `path:line`), drop the rest, and return one bullet-list per
+    prior review. A prior review that had no parseable findings becomes an
+    empty string and is dropped.
+
+    Local import keeps the ollama path dep-free (extract_finding_bullets lives
+    in pilot/diff_compress.py).
+    """
+    from diff_compress import extract_finding_bullets
+    out = []
+    for body in prior_bodies or []:
+        bullets = extract_finding_bullets(body)
+        if bullets:
+            out.append("\n".join(bullets))
+    return out
+
+
 # ---------------------------------------------------------------------------
 # Network helpers
 # ---------------------------------------------------------------------------
@@ -911,13 +1250,35 @@ def review_pr(
             print(f"pragent: {repo}#{index} sha={sha[:8]} already reviewed, skipping", flush=True)
             return True
 
-        diff, _truncated, _orig = fetch_pr_diff(api, repo, index, token, max_chars)
+        raw_diff, _truncated, _orig = fetch_pr_diff(api, repo, index, token, max_chars)
-        if not diff.strip():
+        if not raw_diff.strip():
             post_review(api, repo, index, token, format_review_body("No diff content to review.", model, sha))
             return True
 
         config = fetch_repo_config(api, repo, token, ref=base_ref)
-        prior = prior_review_bodies(reviews, sha)
+        prior = compact_prior_reviews(prior_review_bodies(reviews, sha))
+
+        # Trim the diff to +/- hunks plus a narrow context window. The agent
+        # resends the brief prefix every step, so a 25k-char diff becomes
+        # 25k × 30-step × cached-after-step-1 = hundreds of thousands of input
+        # tokens. Default context=1: enough for the reviewer to see what an
+        # added line is replacing; the full file is on disk in the workdir
+        # anyway, so anything more is reading the diff twice. Tunable via
+        # PRAGENT_DIFF_CONTEXT (0 = +/- only; -1 = disable compression).
+        from diff_compress import compress_diff
+        ctx = int(os.environ.get("PRAGENT_DIFF_CONTEXT", "1"))
+        if ctx < 0:
+            diff = raw_diff
+            compression_note = ""
+        else:
+            diff, orig_chars, kept_chars = compress_diff(raw_diff, context=ctx)
+            if kept_chars < orig_chars:
+                compression_note = (
+                    f"\n\n> _diff compressed: {orig_chars:,} → {kept_chars:,} chars "
+                    f"(context={ctx}; PRAGENT_DIFF_CONTEXT to tune)_"
+                )
+            else:
+                compression_note = ""
 
         engine = os.environ.get("PRAGENT_ENGINE", "opencode").strip().lower()
         review_summary = ""
@@ -934,6 +1295,7 @@ def review_pr(
                 api=api, repo=repo, index=index, sha=sha, token=token,
                 title=title, body=body, diff=diff, config=config,
                 prior_reviews=prior, model=oc_model,
+                compression_note=compression_note,
             )
             review_summary, findings = parse_review_output(stdout)
             if not findings and not review_summary:
@@ -949,24 +1311,48 @@ def review_pr(
                 salvaged = salvage_summary(stdout)
                 usage_section = ""
                 if report_usage and usage:
-                    usage_section = format_usage_section(usage, [], model)
+                    usage_section = format_usage_section(usage, [], model, config=config)
                 post_review(api, repo, index, token, format_review_body(
                     salvaged or "AI review produced no parseable output.",
                     model, sha, usage_section=usage_section))
                 return True
         else:
-            user_prompt = build_user_prompt(title, body, diff, config, prior)
+            user_prompt = build_user_prompt(title, body + compression_note, diff, config, prior)
             raw_findings = call_model(ollama_url, model, SYSTEM_PROMPT, user_prompt, max_tokens)
             findings = parse_findings(raw_findings)
             usage = None
 
+        # Filter / cap findings per `.pr-review.json` (style, threshold, max,
+        # patterns, exclude_tests). Without this every config knob would be a
+        # no-op — the agent has no view into the config beyond instructions.
+        # The synthetic require_tests finding (if any) is appended here.
+        try:
+            changed_paths = sorted({
+                f.get("path", "")
+                for f in findings
+                if f.get("path")
+            })
+        except Exception:
+            changed_paths = []
+        kept, _dropped = apply_repo_config(findings, config, changed_paths=changed_paths)
+        findings = kept
+        if _dropped:
+            print(
+                f"pragent: {repo}#{index} sha={sha[:8]} filtered "
+                f"{len(_dropped)} finding(s) per .pr-review.json "
+                f"(style={(config or {}).get('style', 'balanced')}, "
+                f"threshold={(config or {}).get('severity_threshold', '?')}, "
+                f"max={len(findings)})",
+                flush=True,
+            )
+
         # Attribute output tokens to each finding (mutates finding dicts) so
         # inline comments + the usage table can show a per-comment estimate.
         # Only meaningful when we have measured usage AND the PR asked for it.
         usage_section = ""
         if report_usage and usage and usage.get("output"):
             compute_attribution(findings, usage["output"])
-            usage_section = format_usage_section(usage, findings, model)
+            usage_section = format_usage_section(usage, findings, model, config=config)
 
         anchors = parse_diff_anchors(diff)
         anchored, unanchored = split_findings(findings, anchors)

pilot/opencode_review.py

@@ -286,6 +286,7 @@ def write_brief(
     diff: str,
     config: dict | None,
     prior_reviews: list[str] | None,
+    compression_note: str = "",
 ) -> str:
     """Render `.pragent/brief.md` in the workdir. Returns the path written."""
     path = os.path.join(workdir, ".pragent")
@@ -297,16 +298,17 @@ def write_brief(
     prior = "_(none)_"
     if prior_reviews:
         prior = "\n\n---\n\n".join(prior_reviews)
-        if len(prior) > 8000:
+        if len(prior) > 4000:
-            prior = prior[:8000] + "\n…[prior reviews truncated]"
+            prior = prior[:4000] + "\n…[prior reviews truncated]"
     files = changed_files(diff)
     files_block = "\n".join(f"- `{p}`" for p in files) if files else "_(none)_"
+    desc_block = ((description or "").strip() or "_(none)_") + compression_note
     content = _BRIEF_TEMPLATE.format(
         repo=repo or "?",
         index=index or "?",
         sha=sha or "?",
         title=title or "(none)",
-        description=description.strip() or "_(none)_",
+        description=desc_block,
         changed_files=files_block,
         config=cfg,
         prior=prior,
@@ -672,6 +674,7 @@ def run(
     config: dict | None,
     prior_reviews: list[str] | None,
     model: str,
+    compression_note: str = "",
 ) -> tuple[str, dict | None]:
     """End-to-end: checkout archive → brief → drop factory → opencode → (text, usage).
 
@@ -679,6 +682,11 @@ def run(
     and a usage dict (token/cost totals + `duration_s`), or `(text, None)` when
     no usage events were seen. Raises on any failure; the caller (`review_pr`)
     fails open. The workdir is removed unless PRAGENT_KEEP_WORK is set.
+
+    `compression_note`: a small markdown block to append to the brief's PR
+    description (e.g. "diff compressed: 25k → 12k chars"). Empty string by
+    default. Appended AFTER the untrusted-data fence so the agent reads it as
+    guidance, not author input.
     """
     os.makedirs(WORK_ROOT, exist_ok=True)
     workdir = tempfile.mkdtemp(prefix=f"{repo.replace('/', '_')}-{sha[:8]}-", dir=WORK_ROOT)
@@ -697,6 +705,7 @@ def run(
             workdir,
             repo=repo, index=index, sha=sha, title=title, description=body,
             diff=diff, config=config, prior_reviews=prior_reviews,
+            compression_note=compression_note,
         )
         drop_factory(workdir)
         text, usage = run_opencode(workdir, model)

tests/pilot/test_ai_review.py

@@ -779,3 +779,244 @@ def test_salvage_summary_empty_when_nothing_to_salvage():
     assert ai_review.salvage_summary("") == ""
     assert ai_review.salvage_summary("   \n  ") == ""
     assert ai_review.salvage_summary("```json\n{}\n```") == ""
+
+
+# ---------------------------------------------------------------------------
+# equivalent_cost + format_usage_section equivalent-provider line
+# ---------------------------------------------------------------------------
+
+
+def test_equivalent_cost_matches_cost_model():
+    usage = {"input": 1_000_000, "output": 0, "cache_read": 0, "cache_write": 0}
+    eq = ai_review.equivalent_cost(usage, "claude-sonnet-5")
+    # Sonnet 5 input is $2/MTok, so 1M input = $2.00 exactly.
+    assert abs(eq - 2.0) < 1e-9
+
+
+def test_equivalent_cost_unknown_key_returns_zero():
+    assert ai_review.equivalent_cost({"input": 100}, "bogus") == 0.0
+
+
+def test_format_usage_section_shows_equivalent_provider_cost():
+    usage = {"input": 200000, "output": 4000, "reasoning": 0,
+             "cache_read": 0, "cache_write": 0, "total": 204000,
+             "cost": 0.0, "steps": 6, "duration_s": 100.0}
+    sec = ai_review.format_usage_section(usage, [], "glm-5.2:cloud")
+    # Two cost lines now: an equivalent (default Sonnet 5) AND the $0 actual.
+    assert "## 🔋 AI usage" in sec
+    assert "est. cost on **Claude Sonnet 5**" in sec
+    assert "actual: $0.00" in sec
+    assert "free tier" in sec
+    # Equivalent should be > 0 for non-trivial token counts.
+    assert "$0.00" in sec  # the actual line
+    # And a non-zero one for the equivalent.
+    import re
+    cost_lines = [ln for ln in sec.splitlines() if "cost on" in ln]
+    assert len(cost_lines) == 1
+    assert re.search(r"\$\d", cost_lines[0]) is not None
+    assert "$0.00" not in cost_lines[0]
+
+
+def test_format_usage_section_honors_cost_target(monkeypatch):
+    monkeypatch.setenv("PRAGENT_PRICE_TARGET", "claude-haiku-4-5")
+    usage = {"input": 1000, "output": 100, "reasoning": 0,
+             "cache_read": 0, "cache_write": 0, "total": 1100,
+             "cost": 0.0, "steps": 1, "duration_s": 5.0}
+    sec = ai_review.format_usage_section(usage, [], "glm-5.2:cloud")
+    assert "Claude Haiku 4.5" in sec
+    # 1k * $1/MTok + 100 * $5/MTok = 0.001 + 0.0005 = $0.0015
+    assert "$0.0015" in sec
+
+
+def test_format_usage_section_respects_repo_config_cost_target(monkeypatch):
+    monkeypatch.delenv("PRAGENT_PRICE_TARGET", raising=False)
+    usage = {"input": 1000, "output": 100, "reasoning": 0,
+             "cache_read": 0, "cache_write": 0, "total": 1100,
+             "cost": 0.0, "steps": 1, "duration_s": 5.0}
+    sec = ai_review.format_usage_section(
+        usage, [], "glm-5.2:cloud", config={"cost_target": "claude-opus-5"}
+    )
+    assert "Claude Opus 5" in sec
+    # Opus 5 = $5/MTok input + $25/MTok output → 1000*5e-6 + 100*25e-6 = 0.0075
+    assert "$0.0075" in sec
+
+
+def test_format_usage_section_reports_unknown_price_target():
+    usage = {"input": 100, "output": 100, "reasoning": 0,
+             "cache_read": 0, "cache_write": 0, "total": 200,
+             "cost": 0.0, "steps": 1, "duration_s": 1.0}
+    sec = ai_review.format_usage_section(
+        usage, [], "glm-5.2:cloud", config={"cost_target": "bogus-model"}
+    )
+    # Falls back to default + surfaces the error in the line.
+    assert "Claude Sonnet 5" in sec
+    assert "unknown price target" in sec
+    assert "bogus-model" in sec
+
+
+# ---------------------------------------------------------------------------
+# parse_repo_config — extended schema
+# ---------------------------------------------------------------------------
+
+
+def test_parse_repo_config_new_fields_all_valid():
+    raw = json.dumps({
+        "focus": ["security"],
+        "style": "strict",
+        "severity_threshold": "high",
+        "max_findings": 5,
+        "exclude_tests": True,
+        "require_tests": True,
+        "patterns": {"allow": ["src/**"], "deny": ["**/*.test.ts"]},
+        "cost_target": "claude-opus-5",
+    })
+    c = ai_review.parse_repo_config(raw)
+    assert c["style"] == "strict"
+    assert c["severity_threshold"] == "high"
+    assert c["max_findings"] == 5
+    assert c["exclude_tests"] is True
+    assert c["require_tests"] is True
+    assert c["patterns"]["allow"] == ["src/**"]
+    assert c["patterns"]["deny"] == ["**/*.test.ts"]
+    assert c["cost_target"] == "claude-opus-5"
+
+
+def test_parse_repo_config_rejects_bad_style_and_threshold():
+    c = ai_review.parse_repo_config(json.dumps({"style": "wild", "severity_threshold": "meh"}))
+    assert "style" not in c
+    assert "severity_threshold" not in c
+
+
+def test_parse_repo_config_caps_max_findings():
+    c1 = ai_review.parse_repo_config(json.dumps({"max_findings": 0}))
+    c2 = ai_review.parse_repo_config(json.dumps({"max_findings": 999}))
+    c3 = ai_review.parse_repo_config(json.dumps({"max_findings": "12"}))
+    assert "max_findings" not in c1  # 0 invalid
+    assert "max_findings" not in c2  # > 30 invalid
+    assert c3["max_findings"] == 12  # numeric string accepted
+
+
+def test_parse_repo_config_caps_patterns():
+    raw = json.dumps({
+        "patterns": {"allow": [f"a{i}" for i in range(20)], "deny": [f"d{i}" for i in range(20)]}
+    })
+    c = ai_review.parse_repo_config(raw)
+    assert len(c["patterns"]["allow"]) == ai_review.CONFIG_MAX_PATTERNS_ITEMS
+    assert len(c["patterns"]["deny"]) == ai_review.CONFIG_MAX_PATTERNS_ITEMS
+
+
+def test_effective_config_applies_style_defaults():
+    eff = ai_review.effective_config({"focus": ["security"]})
+    assert eff["style"] == "balanced"
+    assert eff["max_findings"] == 12
+    assert eff["severity_threshold"] == "medium"
+    assert eff["focus"] == ["security"]
+
+
+def test_effective_config_style_overrides_fields():
+    eff = ai_review.effective_config({"style": "strict"})
+    assert eff["max_findings"] == 5
+    assert eff["severity_threshold"] == "high"
+
+
+# ---------------------------------------------------------------------------
+# apply_repo_config — filter findings
+# ---------------------------------------------------------------------------
+
+
+_FINDINGS = [
+    {"severity": "critical", "path": "src/main.py", "line": 1, "problem": "p", "fix": "f", "suggestion": ""},
+    {"severity": "high",     "path": "src/main.py", "line": 5, "problem": "p", "fix": "f", "suggestion": ""},
+    {"severity": "medium",   "path": "src/main.py", "line": 9, "problem": "p", "fix": "f", "suggestion": ""},
+    {"severity": "low",      "path": "src/main.py", "line": 13, "problem": "p", "fix": "f", "suggestion": ""},
+    {"severity": "high",     "path": "src/FooTest.java", "line": 22, "problem": "p", "fix": "f", "suggestion": ""},
+    {"severity": "medium",   "path": "src/app.test.ts", "line": 7, "problem": "p", "fix": "f", "suggestion": ""},
+]
+
+
+def test_apply_repo_config_severity_threshold():
+    kept, dropped = ai_review.apply_repo_config(_FINDINGS, {"severity_threshold": "high"})
+    assert len(kept) == 3  # critical + 2 highs (main.py + FooTest.java)
+    assert all(f["severity"] in ("critical", "high") for f in kept)
+    assert len(dropped) == 3
+
+
+def test_apply_repo_config_exclude_tests_drops_test_files():
+    kept, dropped = ai_review.apply_repo_config(_FINDINGS, {"exclude_tests": True})
+    paths = {f["path"] for f in kept}
+    assert "src/FooTest.java" not in paths
+    assert "src/app.test.ts" not in paths
+
+
+def test_apply_repo_config_patterns_deny_drops_matching():
+    cfg = {"patterns": {"deny": ["src/main.py"]}}
+    kept, dropped = ai_review.apply_repo_config(_FINDINGS, cfg)
+    paths = {f["path"] for f in kept}
+    assert "src/main.py" not in paths
+
+
+def test_apply_repo_config_patterns_allow_keeps_only_matching():
+    cfg = {"patterns": {"allow": ["src/main.py"]}}
+    kept, dropped = ai_review.apply_repo_config(_FINDINGS, cfg)
+    paths = {f["path"] for f in kept}
+    assert paths == {"src/main.py"}
+
+
+def test_apply_repo_config_max_findings_caps():
+    kept, dropped = ai_review.apply_repo_config(_FINDINGS, {"max_findings": 2})
+    assert len(kept) == 2
+    # Highest-severity first (critical, then high)
+    assert kept[0]["severity"] == "critical"
+    assert kept[1]["severity"] == "high"
+
+
+def test_apply_repo_config_exclude_paths_glob():
+    cfg = {"exclude_paths": ["src/main.py"]}
+    kept, dropped = ai_review.apply_repo_config(_FINDINGS, cfg)
+    assert "src/main.py" not in {f["path"] for f in kept}
+
+
+def test_apply_repo_config_require_tests_synthetic_finding():
+    cfg = {"require_tests": True}
+    changed = ["src/main.py", "src/lib.ts"]
+    kept, dropped = ai_review.apply_repo_config([], cfg, changed_paths=changed)
+    assert any(f.get("_config_synthetic") for f in kept)
+
+
+def test_apply_repo_config_require_tests_no_synthetic_when_tests_present():
+    cfg = {"require_tests": True}
+    changed = ["src/main.py", "src/main_test.py"]
+    kept, dropped = ai_review.apply_repo_config(_FINDINGS, cfg, changed_paths=changed)
+    assert not any(f.get("_config_synthetic") for f in kept)
+
+
+def test_is_test_path_recognises_common_patterns():
+    assert ai_review.is_test_path("src/FooTest.java")
+    assert ai_review.is_test_path("src/foo.test.ts")
+    assert ai_review.is_test_path("tests/foo_test.py")
+    assert ai_review.is_test_path("test_foo.py")
+    assert ai_review.is_test_path("packages/app/__tests__/foo.js")
+    assert not ai_review.is_test_path("src/main.py")
+    assert not ai_review.is_test_path("src/testing.py")  # "testing" ≠ "test_"
+
+
+# ---------------------------------------------------------------------------
+# compact_prior_reviews
+# ---------------------------------------------------------------------------
+
+
+def test_compact_prior_reviews_drops_prose_keeps_bullets():
+    bodies = [
+        "🤖 AI Review · m · `abc`\n\nLong prose.\n\n- **[HIGH]** `a.py:1` — bug.\n- **[LOW]** `b.go:2` — nit.\n\n_2 inline comments posted._\n<!-- pragent:sha=abc -->",
+        "Just chatter, no findings.",
+    ]
+    out = ai_review.compact_prior_reviews(bodies)
+    assert len(out) == 1
+    assert "HIGH" in out[0] and "a.py:1" in out[0]
+    assert "Long prose." not in out[0]
+    assert "inline comments posted" not in out[0]
+
+
+def test_compact_prior_reviews_empty_and_none():
+    assert ai_review.compact_prior_reviews([]) == []
+    assert ai_review.compact_prior_reviews(None) == []